NO TOOLS ?  NO JOY !          

The Suzuki Sidekick or Geo Tracker car: (mostly engine related)    SEE THE CHEAP TOOLS SECTION NOW.  "no endorsements,  this is all low ball, may be one time good tools, in a panic, we do this"
This page is for skin flints.
 For sure, there are far better tools, and last longer, this page shows tools that can be used once and thrown away. ( There is always SEARS and SNAP-ON)
Many folks have  $500 car, and will  never buy a $300 Snap-on timing light, IT WILL NEVER HAPPEN.  This page is for you.
HF tools are not PRO tools (in my opinion) nor for keeping for a life time in the tool box.  They are just for emergancies, or the like.   Please pick a tool that matches your needs,  top brands or not.
If you have no extra money for tools or just want to inspect for things gone wrong, see here.

For sure vehicle inspections end to end can in fact find may flaws, and bad parts.   (the ECU just hates, corroded connections of any kind)
I have a wits end page on engines , a set of 40+ linear checks .
Besides inspections (wires fell off EFI sensors ) and sure, one can tune up the car with a couple of wrenches.
( Do the 60,000 mile tune-up , bingo !,  many engine starts running correctly, be sure to change the spark wires, one at a time.)
I have a friend, he fixes everything with a single pair of Pliers.  Nobody can work on his car, everything is rounded off.  Go figure...
As you gain tools, you will discover less things break by accident.   I'm not here to judge you ,only to help you make discoveries.

You can change fluids, almost tool free. ( 1 or 2 wrenches?)  You can inspect for   damage, for free with no tools, especially wiring.  
Missing parts?, hacking (after market alarm installations, Audio hack jobs Installed, remote start devices, cruise controls,  etc.)
Any Previous owner that hacks up, the cars ELECTRONIC FUEL CONTROL (EFI) primary wiring system, in my opinion, is asking to get stranded. 
(These upgrades ?, can be done right, but needs to be done  so, with high quality connections and be sure that a regression path exists)
Be sure to start off , on  a strange car, by doing a full inspection for hack jobs and wrong or missing parts.  (fuel leaks, brakes are first)
 The FSM for this car is like $15 , sold cheap , used on Ebay , that Factory Service Manual, has AMAZING quality electrical drawings ! 

You can not effectively diagnose/repair  engines blind (no tech books), and  without hand wrenches are obvious , You can make some tools by hand (DYI)
To really  make progress fast, it takes, Gauges and meters.
You do need a compression gauge, vacuum gauge ,  fuel pressure gauge ,  a timing light (strobe) better is one with a tachometer and a DMM.  (a hand vacuum pump tool, is also necessary)
Most young people buy tools, as they need them , and after a few years, you have a nice set. 
Each hour labor saved in a local repair shop, can buy  4 tools, on average.   I consider tools , free, for that reason and after 25 or 50 years, they earn cash, better than some 401K's.
I will not show my most expensive tools, but will show cheap tools, so that persons needing that, can find them.
Anyone can buy expensive tools and go broke, easy. I will not bore you with that path...  But do shop around and check for sales and deals, or the flea market. 
At Garage sales, I scoop up whole sections of tools cheap.  See em'. grab em'. cheap. Be Proactive !

Consider this:
(A scan tool can save you in a vast numbers of ways) On a 1996 or newer car it's mandatory IMO)  < it's an investment , in the true sense (pay back!).

The rules for testing and engine diagnostic are: (in this order too)  To do each step below requires tools. 
Engine running problems?:

  1. Good motor?  (ok, the starter makes noise, so what?)
  2. Good spark?  ( 1/2 the test is free, the advancing part , not)
  3. Good fueling.? (there are visual tests)
You can not discover the truth with out gauges.  (The cylinder compression needs to be above 150 PSI,  you can not guess that it is good.)
You can not guess that the spark is good. (3 tests there are: spark to each spark-plug tip, static timing, and full advance timing checks)
A question:
Sir, why do we test for  full spark, if the ECU controls that 100%?  (exception, 89/90' years are Distributor IS ONLY self contained centrifugal/vacuum spark advanced )
Answer: The ECU retards spark vastly in LIMPHOME, you need to know that this is happening.  This is a top clue, as to what is going on.

Torque (wrench) specifications:

Stage1:  (Basic Repairs & mostly tuneup's  "The 60,000 mile" , service and replacing a known bad part.) 

A full set of  open end box end wrenches and socket sets. All in  metric. (yes, the car is 100% metric, so skip that SAE kit of tools)
8mm to 24mm (then, buy them, as you need them)
A 17mm deep wall 1/2 drive  socket is needed for the front crank pulley bolt (60k tuneup , needs a new timing belt)
All sizes of screwdrivers:  slotted and Phillips.
Feeler gauges (for 60k lash and spark gap)
Both sizes of torque wrenches. A 3/8" drive  100 inch lb    and 1/2" drive 200 foot-lb.  Take care torquing those 6mm bolts.
A HD  3 ton +  trolley jack.  (HD = Heavy duty)
A HD jack  4 ton stands (no spot welded, junk )  (do not cheap out, on stands !)
Oil drain pans,  funnels (walfart)
The factory FSM (yes, books are tools too)   See my never do page, for safety.
1 spare new spark plug,  for testing, keep it in the glove box of all old cars.  keep the gap at 0.028" (factory spec. minimum)
Go to the  NAPA Auto store and buy a bulk gasket kit sheets set.  and an Exacto knife to cut your own gaskets.

A Full 1/2" drive  socket set (metric) (with deep wall)

Add Shop air:
Shop air, and air tools ( build the tool base and speed disassembly ) Time to buy that 1/2 drive, Heavy duty Impact gun now.
A tire chuck air fitting , you can fill your own tires with air now.

You are loaded for bear and ready to work the whole car and  motor. (one extra tool is a slide hammer (rear axle) and a gear pullers)
The front axle wheel bearings have a special tool seen at the end of page.

STAGE 3:  (analytical tools , with out which any serious car repairs will fail)   For just about any sick engine, you will need these tools. see them below.
Gauges !
A scan tool (see below) (do not buy a near useless code reader)
Compression, fuel and vacuum gauges , the triad of success!)
You must have these or you will never find a bad engine. These tools prove the motor can pump air!
A cylinder leak down tester is also a  great tool to own. (will show you,  if rings or valves leak, and overall engine condition, used with compression gauge is best)
DMM , you must have at least a $20 buck Digital multimeter.  seen below, in the photo section at end.
You are loaded for bear and ready to test any motor.
(one extra tool is a slide hammer and a gear puller)
Shop air, and air tools ( build the tool base and speed disassembly )

Stage 4:  On Board Diagnostics (something inside the cars computer brain or ECU/PCM)
( An OBD scan tool is an investment, for this car and future cars and is and investment , with a real pay back)
(89-95 the CEL lamp will always blink out DTCs code )     If short for cash, you can buy a $7 cloned ELM tool.

See 1996 and newer SCAN tools example , here.

OBD1 only:  (on board diagnostics)
89-95'  covered here All SCAN tools:
There are no over the counter  scan tools for Suzuki/GEO  OBD1 cars, there are some home grown experimental OBD1 tools  here is 1 example.
Autozone can not scan your pre 1996 car, no way , no how. Save the gas.
Most/many? Suzuki and GM shops long ago, lost their very rare TECH1 scan tool.
Many dealers and such, can't even remember the CEL codes or have any books on the car at all.  
Most GM dealers say, GEO what? what is that?

NO tools Repairs  (or a low minimum $):  Almost every tool here, is near $20 and in total, is less than 1 hour shop labor.  So in my book, the tools are free. Used 1 time, they are all paid for. See?
If really a tight wad? or skin flint like me?,  You can use them one  time, fix the car, box them and sell them all on ebay.  Lots of options, huh?
When I say no tools, that does not mean , no 10mm spanners, and 3/8" driver metric socket set, if you really are tool free, maybe you should find a qualified, ASE certified mechanic.
Bring the FSM with you, as most mechanics never seen one of these rare beasts (rare to them, not you) Nor do they know Suzuki OBD1 , queer methods.. (hint, point to page in FSM and grin)
I painted the free tests, in red below.
For about $100 all the tools below can be had. See my running list here at end of this page..

This  page  shows how to find  problems by accident or by pure hard work or luck, in a linear and non logical fashion.  
( It can happen  !) (Time and money do interchange) Some times pure raw luck beats skill, and hard long work.  (not on average, Mr. Murphy rules there)
Working on any car FSM free, is a receipt to endless pain and horrors, not only to you, your car, but to general safety and the life of the car and its parts.
Each car design, is unique and the FSM is the magic crystal ball to that Uniqueness, no matter how many cars you repair, or training, all cars have uniquenesses.
If all else fails RTM (read the manual) or RTFM ,  just because something seems simple?, is usually just  a noobs dream, asking someone to repeat the 100 pages, in a forum is nuts.

I call this The "DO and PRAY". 
I do not advocate guessing and throwing parts,  or listening to others on the forums with their USELESS , "mine did this or that" or endless testimonials.
Some problems can be caused by 100s of different things. Some cars (common after 20 long bad years)  have 3 serious malfunctions, all ignored by the PO (previous owners )
So consensus is useless , in my opinion.  "study Misfire and you will agree"?
Ask for help with real troubleshooting and WIN!
This is not a troubleshooting guide, we give that up with no tools.  ( the hallmark of a good shop is good troubleshooting skills and tools)  We now digress to...
Sometime we do give up and after cleaning the EGR main, replace it.  (other do, at suspicion , as they have not time to deal with that nasty part,  I can not blame you !)

This page is for Engines not running correctly.
There is no rhyme or reasons below, or logic, it's a list of things you can do, that are free or dirt cheap. (except #1 and many times #2)
My engine runs... or don't at all ....
Crappy,  Misfire, stalls, dead, or  hesitations, power loss, flat spots, bogging , huge mile per gallons usage, and the like.  All that is here, but this link takes tools

If  the motor does start. and since it does that, then the  fuses are good , but do check the DOME fuse.

The ECU (and ignition) must have full electrical power at all times,  11 vdc to 15 vdc ! , yes, a voltmeter               (if not? stop , do not pass go,  fix that)

Look at all fuses, if they look blown out, well, they are. (some look good and are bad, use a DMM set on ohms to find them bad or good. The DMM never ever lies.
  1. The check engine light must glow at key on, or there is serious ECU problems and most go out running, if it stays on running,  then pull the DTC errors. DO  NOT SKIP THIS STEP.   a 1 cent paper clip 89-95' !
  2. Clean the EGR MAIN valve, the #1 cause of problems on all cars and stalling at every traffic stop? or even parked?
  3. The spark plugs remove easy , are the TIPS LOOKing  black with carbon?, and/or fuel soaked, or dripping with raw fuel?  Well?  it  is flooded or is flooding! Use full throttle cranking, to evoke the magic unflood mode.
  4. Remove the dizzy cap,  is the rotor spinning, while cranking, NO, look down oil filler hole, is the cam spinning? cranking, ? NO?  then the timing belt snapped (stripped) Skipping the 60k tuneup was the cause!
  5. Open the hood and look for , broken, disconnected, missing or mangled sensors on the engine or main induction pipe, or at Air cleaner.
  6. Examine every engine bay harness and its connection points for damage.  (do the same to wires entering behind  ECU)
  7. Look for missing and cracked , melted, missing ,loose, or clogged  hoses.  ( or some dweeb plugged it up on purpose , yes, blow through said hoses, is it clogged up or leaking?)
  8. Is your car HACKED,  one guy found a missing MAF, or some mad owner wired in a 3 different alarms and none worked, but left a horrid bad primary EFI wiring.
  9. In N.America ,you can look under the hood and behold a vacuum sticker showing the proper vacuum routing, or look here , check the hoses for mis-routing.
  10. Examine all engine bay grounds for damage or corrosion. Have the battery tested.  The ECU hates LOW battery voltages.  A new battery or repair charge system.
  11. On all 2 door kicks , remove the left rear tail light lens, check to see that fuel pump ground screw/lug?, that kills more fuel pumps.
  12. Is the gas bad? check a sample and let it settle , looking for bad stuff to settle out. (water , oil , dirt ,rust , green slime? , red Fungus?.)
  13. blank
  14. Does the engine coolant  reach 180f (82c) at least and hold there not dropping?  (a pyro gun works best $20)  
  15. Get engine fully hot , 20 miles driven? and if top rad hose is too hot to hold, your and flies off?, the above tool is not needed.  but does the temperature fluctuate?  tools do rule the roost.
  16. Do the long lost TUNEUP , not ever done or not done in 60k miles.  Full ignition parts , cap ,rotor,wires, sparks, air filters and FUEL FILTER.  Sorry not free, no tuneup is.
  17. An ASE mechanic would do a vacuum test , a compression test and a fuel pressure test, at the get go, but you can't  , so we will spin the guess dial and says MOTOR IS GOOD.
  18. At this point good motor and we pray for good REGULATED fuel pressure .  So we next check the battery voltage at rest and running,  12.6v resting and 14.7v running.
  19. No scan tools, so we whip out our trusty $5-$20 DMM  and then check all sensor on your car with this sensor test page as your guide (100% coverage)
  20. I bet that OBD2  $59 scan tool looks better every minute, no? (not for pre 96 cars , at all !) {not for non USA cars , do your own research for truth here, complex}
  21. Test the TPS , ECT , IAT, and for proper resistance, and at 2 temperatures for the IAT and ECT.  Check the TPS and calibrated  as the page states.
  22. Induction leaks?: The 8v the motor races fast and a 16v the engine bogs, lean bogging. (complex) do the idle speed and leaks tests here, or the many alternates here.
  23. A rubber hose is 50 cents,(free) place one end in ear, and play other end near all (motor running) intake parts,  Listen for Hissing sounds. (bad)
  24. Check the ISC coil for 6 ohms, pre 91' and 12 ohms 91'+ and newer KICKS.  Apply 12vdc to this device and see that it opens with 12v and closes without 12v (blow through it)
  25. Does the ECT read 300 ohms on a hot engine? ( unplugged ECT , meter connected to said sensor  only) , a fully hot engine?)
  26. Before a first start in the morning, does the ECT equal the IAT , resistance ,unplugged , both?  yes, good test !  (10% accuracy)  see the chart here.
  27. if the engine still runs bad, replace the Oxygen sensor (aka: Lambda )or an 0 sensor,  the front sensor, not the rear (if you  have a rear sensor the car is 96" or newer year.)
  28. Some JDM cars have no Oxy sensor at all , so you guys forget that. (some JDM have no EGR devices) some again, have no CAT !
  29. blank
  30. Listen with a rubber hose in your ear, for leaks, all around the exhaust manifold.  And Header and down tube to the CAT converter. if yes, the O2 sensor will never work right.
  31. If motor is 8 V  (not 16v )  pull air horn, look down throttle bore, and have (91-95') helper key on 3-5 times, no start, and see if the injector leaks.  TBI only.
  32. On 89/90 8v cars, you must crank motor , then cut the key to off , to see fuel leaks, only cranking builds fuel pressure these years, above 10F ambient.
  33. If the injector leaks repair that. On 16v you need fuel pressure gauges to do leak injector down tests.  sorry !  a $20 tool.
  34. Make sure the 8v injectors squirts cranking and stops squirting the instant you cut the key to  off.  just LOOK !
  35. Send the injector(s) out to be cleaned.  $19 each. but first try Chevron Techron in the fuel, ( other brands (most) are worthless) read the bottle see benzene, that works.
  36. If the injectors are partially clogged (you guess) run Chevron fuel, at the next fill up, just maybe Chevron saved your day.? 
  37. When you replaced the fuel filter at the tune up , drain it backwards and see what comes out of filter, rust, water, green slime?  The whole fuel system may need cleaning.
  38. blank
  39. On most EFI  based engines, you can listen to injector(s) click with a $5 stethoscope (not free) , see INJECTOR TESTS.  a huge list of tests.
  40. (the 8v is very hard to hear the clicks ,cranking due to the huge background noises of the starter motor etc, 16v is a cake walk.)
  41. blank
  42. Yes, one more, did the cam belt slip. Only takes 1 wrench to find out. See Sneak a peak method.
  43. blank
  44. If someone spun the distributor willy nilly, you might guess it back , correctly here, in fact, I'm sure you can., do the coarse settings.!
  45. Free , is the dizzy base loose in its mount ? free to look at any time. just grab it and try to move it.
  46. At this point, all things easy to find and fix may have been found , above. But?, if Not, it may be  Time for  the Trouble shooting  pages.
  47. One  more free test,  spray water (old Windex bottle?) on to spark wires running, does the motor now misfire, bingo! , a bad wire set.  60k service skipped again.
  48. In the dark, does the spark wire flash over (sparks) Bingo bad wire set.
  49. end.
I hope I got all the easy tests, here and some free.  I tried.
My parts on car, finder page is here.

My prescription for Trouble shooting, is this:  I call this the WIN plan:

The top element here,  is to be sure the motor is good.  If not , all else is window dressing.  And point 2, if the engine is timed wrong, the EFI will injector WRONG. (so fueling issues are LAST)
I do hope this page, helps you solve your Sidekick running problems.!
Happy Trails to you !

ools that really help: (sold at all Autostores and even large Walmart's and good old Harbor Freight. "Fright?" (very cheap , so cheap , just use and throw away !)  
This section of tools are for skin flints.
Dirt cheap tools, many  cost  less than one hours shop labor ( they are INVESTMENT GRADE, with full pay back for a life time of fixing cars)  In fact use one , one time and pays back 5 to 10 times.
There are, in fact far better tools sold, but this page is LOW END ! (I get asked this all the time, so.... )
The first 6 , belong in all tool boxes, if you wish to make any fast progress. ( Some of mine are 45 years old and work like new)  OK, buy as needed, that is what most folks do.
My 40 year old timing light would cost me $400 in todays inflation adjusted dollars.  (and still works like new)
My new timing light has  tachometer. for $23
Buy the tools or pay someone $100 per hour to use theirs.  The only dangerous tool here is the fuel pressure guage, please do where goggles and depressurize the system first.  (the FSM repeats this 100s of time)
There are only 2 choices, here. (besides pure raw luck) No human on earth ,can measure 28 PSI or 150 PSI with finger tip or dribble  checks.

It is not the choice of any Pro. that expects them to work hard every day of his life.  But you can get by, with these tools. (case in point , in the store I saw the needle had fell off, so I skip that one...LOL)
That fuel pressure guage below comes with the exact SUZUKI adaptor (on far right of photo !, it fits on the fuel filter Banjo fitting, 6mm test port perfectly)
The first 8 tools below are all sold at harbor fright (freight).
Keep in mind the instuctions with these cheap tools are horrible. (Chinglish? translated)  It assumes that you know how to use it.
The Fuel pressure fits all Sidekicks, off the shelf in the store,  many in the box new, had a loose needle , so you luck may vary.
 Do not fail to examine the tool carefully in this store, before purchase (these are all LOW  END TOOLS)  (I use them as emergency  backups to real tools)
The first 7 tools below are Harbor Fright(pun) tools, YMMV.

Compression Gauge.   (First 6 are $20 tools)                                                     Fuel pressure                                                      Vacuum (left) and pressure on right for CAT back pressure !

Hand Vacuum pump , and brake bleeder  (rubber fittings, are junk)          An  I.R. Pyro gun    (Vast usage)             A $20 automotive Spark timing light, xenon strobe type, (better?) with inductive pickup..   Fails?                                  

$5 tool, very handy and cheap, use  to find noise anywhere, or find bearings about to fail.                        $35  stethoscope, use better head phone muffs.             The battery load bank, and charging sys. tester.  

       The DMM   $20 to $400       Hoyt SG-1 Amp Clamp       The TENMA / DC Amp (clamp)  $54                       TDC finder tool                                           Combustion leak detection for RAD
                                                                                        click below to zoom me.
                                                                                                                                                                                                        NAPA Auto supply. PN.700-1006 @  $35

Current AMPS:
The short finder tool  25100 above ?, works better and cheaper, than any meter above  for less than $30 and has the circuit breaker included (red tube).   Sold  here.
At $25 and can find shorts, easy.  See the video here.

The Hoyt tool above does not do battery phantom drains well , as it can not resolve below 5 amps well.  But they do sell may different types of gauge.

The Tenma 72-7224 works the best, for drains, shorts , alternator current and starter currents. It does it all. But is $55.

A good general purpose meter can be had at Walmart.(ordered)   (or on sale for $83 at some stores "ebay") A Nice High Res. image below. See the full features here.
Does RPM and Duty cycle, too. 

If you ever have an intermitant problem with 12vdc power or sensors.  Nothing beats a logging, DMM. 
This USB logging meter the UT71D or E works great.

See a seller here, pick one that is best for you.

Nothing works better for finding glitches. (no DSO scope)

The sonic injector sensor tool below, is one more very handy tool. It excels on V6 engines ,with hard to reach inectors. (it is tuned to the frequences of the injector pentle valve !) (this same company makes spark detector tools, too)
     @~  $80              

One of the first tools to buy, in a shop is a battery charger. (and 10x that , if you only own 1 car.)  Alway charge the battery, before testing it , or get stuck buying a new battery when yours is good. a $120 mistake.
The grade of charger 2/10/50 Amp charger, can get you cranking in 2 to 4 hours, or even less.
  1. You charge up that weak or dead battery to 12.6v (normal ambient temp.'s) and then use load meter tool , see  meter below right, see the tops scale; about 12.6v is a charged battery. (rested, if higher that means its not rested, called surface charge)
  2. You have the load bank meter connected, and flip the bottom spring loaded switch for 10 seconds, (car key off) and see the yellow box below that shows, 10.2 to 11.4, this is the load bank test. ( this load bank is 50 amps load inside, it gets hot inside)
  3. You crank engine and the yellow weak/ or green 600 scale  there,  you want to crank and be in  the green there. This means the battery is strong enough for cranking. (if this fails and the battery is  charged , then the battery is end of life) {or the rare shorted Starter}
  4. Last is the charging test,  you start car, and look at the right side of the scale. see OK? in Green. I must be or the charge system is faulting.  (do not use the load switch , running engine, as that overloads the Alternator)

$50                                                                                                                                                                  $20


Home made TOOLS, (1996 here, all years work )  crank Cog  puller,  (I have a steering wheel puller that is almost the same style)
Takes 15minute to make. 
Most Sidekicks this cog falls off, due to BAD SERVICE. (the 94foot/pounds TSB nobody reads)?
 It's not an interference fit, it's a perfect fit  , so perfect in fact , the hand can't  pull it off, (like new, day1 , new car ) 
CL means Center line (drafting jargon , sorry) or where the center punch needs to be punched. That shinny chrome part is a 18mm metric socket )

Crank flywheel  locking tools. (home made DIY)

Real SCOPES are not cheap, but you need one that will not blow up, with car wiring NOISE (Killer spikes)  ( you can buy a uses boat anchor scope for $50 used, from the dark ages of electronics , and all work perfect on cars)

CQ-5010  , LOW COST AND SMALL.   (a top tool for checking any thing pulse modulated)

at Ebay sure EBAY?
The above scope inputs (BNC left) is good for 400V. (DC+peak) (good for vehicle work)

Use to see injector signals, ISC  idle duty cycle on ISC valve and that pesky 02 sensor, and see closed loop working or not. or discover if ECU is lost (pre 96' cars) or stuck on limphome.
Always use a 10:1 probe as the input. To protect the inputs of this cheaper scope.
Most dirt cheap scopes sold on flea bay are junk, and will not last on cars electrics ( many are toy 5vdc input max. scopes)

Tek scopes can take 400 to 600 volt spikes, but many cheap scope can not. (some are 60 volts max or less the cheaper the new scope the worst this  gets)
Most  cars use PWM  signals   so   this tool is the only way to see those signals and see the true  flow rates.  PMW = Pulse width Modulation, like our ISC uses.   (50% duty cycle setting on the ISC)
Great for seeing 02 oxy sensors signals on relic pre 1996 cars.   .(good for vehicle work)
Always use a 10:1 probe to best protect your scope from spikes.

The amp clamp probes are here, for  more advanced testing..

My scopes TEK,  are cheaper and better, they are USED, I rebuild my own , scopes.  Boat anchor scopes work great.

Back when:
We did not have scopes  with brains (Allen Turing), that tell you DC volts or RMS. (root mean squared)
We didn't have scope cursors  (processors) back  when, we had to use MATH ; using  1.414 and .707  X, to convert  P-P (peak -peak)   A.C. scope readings to RMS.  RMS means the same energy levels as DC.  many tech.'s, today many tech.'s don't even know these facts.
1v RMS = 1 vDC.  so 1 watt RMS =  1 watt DC. this is the reason for RMS. 
The scope can find a bad, slow ,dead , 0 sensor, a bad or soon to be bad fuel pump (noise) a bad hall sensor, a bad CKP sensor.
The 02 sensors swing about 6 times a second (called cross counting) if slower, the 02 can be old and slow.
Any noisy Alternator or one with 1/3 loss of power (if 1 of  the 3 phase diodes is blown or shorted) The 3 phases can in fact be seen with a scope.
Any time electronics, devices mess up, check the power feed for noise using  a scope.  (I've even see bad powersupplies oscillate at 20 kHz and devastating effects.)
The scope can trace and find noise sources , like no other tool can.
We can also use  the scope to see bad brushes in DC motors, the fuel pump can be seen to be starting to fail (1 dead commutator segment bad  (early).
(My TEK) digital,  and on the right the old and much loved 465 doing my crank sensor.

Scan tool Savings:  The Vulcan Mind Meld?. 
  1. OBD  told you  via  (DTC error or sensor PID'S) what was wrong, saving you long hard hours of work, of finding it by guessing, or testing each sensor by hand.  (told means COMMUNICATED to you by any means)
  2. Saves time  , time to find each problem and reduced down time. 
  3. Shows you what the ECU sees (inputs) so you will not be fooled by taking bad readings with your hand meter. Use a scan tool or waste long hours testing sensors 1 by 1 , by hand.
  4. Saves huge labor costs, and wasted cash replacing good parts.
  5. Reduces Guessing.
  6. The ECU is not deity like, but  in 1996 and newer cars, they added more and better monitors. It can not report all problems, I fact, it is blind to many.
  7. Newer cars with vast numbers of DTC  , the scan tool is not an option at all.

The IR (infra red) Pyro Gun has vast usages: Seen in the photo above   and seen here too,,,, ( I use this in addition to my DMM thermistor probe )

It saves, more burned hands then any tool I own.  (not to mention toxic antifreeze leaks and no need to remove rad cap hot ever) {yes check top rad tank level cold} The tool has vast usages.
Before doing any coolant system checks the engine must be 100% up to full operation heat  (5mile drives don't work), on a stock car that is 180F minimum. (a bad or wrong thermostat or missing rubber ring (post 92year) or seized clutch fan, all prevent this.
Fix the overheating engine or frigid first.
Keep in mind, the hoses and objects measured will be about 20 degrees less than the coolant. ( learn what your car does first, when its working right, then you have a record to compare)
I run a 195F thermostat. (for better cooling and better economy ,and faster warm up,  the STAT delays opening longer so the engine block heats faster. All good.  (the cooler the air and the hotter the coolant ,them more cooling capacity you can get. )
  • You can find clogged up, Radiator tubes (measure top then bottom, if not a huge drop in temperature from input side (top is input on G16 engines) then the tube is clogged (see my thermo-gram) {over heating}
  • Is the ISC or IAC path blocked ( the IAC is key, should read 150F or more, or  fail, they must have perfect flow to reach 150F, find the blockage?, see thermo-gram above. (too fast idle?)
  • Find an overheated engine,  the dash gauge is vary inaccurate (it has no numbers on it!) use the tool to see if the thermostat even works right or is slow or way off regulation temperature. (180,192,195F) Shine on the thermostat housing.
  • The cab heater (HVAC) is weak?.  No flow and heat to the cab heater core.  The pipe/hose  look for a temperature drop on the 2 hoses, fan speed on max.  It must drop, thermal readings, or the path is blocked.
  • Dead weak exhaust ports, shine this tool on each port ,the colder port (header) is the dead cylinder.
  • Shine them on disc rotors or drums , after driving, (at a test drive not using brakes) so see if they are hot, if hot? , then the  brakes are dragging. (do so off road and use a hill to stop car, accelerate on some dirt path ,coast to stop, then test.)
  • You can use this tool to test the CAT converter.
  • You can test the fan clutch to see if it works correct cold and hot.  Just shine it on the  hub. (cold and seized, or hot and slipping?)

The 5sp gear box and transfer case 10mm  square drive   plugs removers:

Searching for this is easy on Google shop.

The Timing light don't work?   High Voltage or HV spark system.
This is common, for all COP coil engines, after all there is no HV spark wire, so we add one,  they sell COP extension leads, buy one if you have  J18 or newer larger engines. USA.  J20, J25, J27, and larger.
The newer the car the more the COP has shielding,  so buy the extension and make it work right.

It is also common for all inductive lights to fail , if the spark plug is dead, (open and not firing or shorted) or the #1 wire is dead open, try #2,3,4 wire ah it's just #1 failing, the #1 cap terminal is carbon tracked? or the #1 HV spark wire is  bad.?
Move the mag pickup clip to many places on the #1  HV wire.  (bingo now it works,  good.)

You have weak spark,  can happen.  Use a spark test tool that measures the energy level. 50,000v  is normal. not 10k.
Snap-on(tm) sells a timing light for $300  , and can fail for the same reasons. The one with a tachometer is best.
All mag timing lights fail for no current spike!

If engine has very old carbon string core wire, please just throw them away, they are junk.  By a set of BOSCH mag wire for $25
For inductive pick up's to work there must be HV, and for sure a magnetic pulse, if the spark plug fails to fire, there may be no pulse. (this depend an the path of current , all  unpredictable with so many paths to fail)
The distributor cap can carbon track, even not seen inside.  This will cause no current to flow down #1 spark wire and  most timing lights fail .
There is aways the 1950 NEON light below (retrograde)  Made of Bakelite (dinosaur  plastic)
 It too, may fail with a dead spark  plug.   The Innova tools sold at Walmart are far better tools.
Do not touch this tool below while, using it,or you will get shocked bad,  that is why we now use MAG pickup lights. to avoid all that FUN.
Old NEON DOG ! circa 1960's

The Vacuum hand tool is great, but rubber fittings in the box are totally 100% useless crap. I have a set of Mityvac 90 degree  nipples that are perfect....

The best is the last, a DMM meter that actually works for RPM ,Dwell and DUTYCYCLE   , On Ebay search MTS-2800B, You can now set the ISC duty cylce to 50 easy.

You will need a tachometer if the one in the dash is dead or missing (2wd does not have one)
Here are all ways to get this tool cheap.

rev 8 5-9-2013  , added, free red codes, for those with no cash at all.  and are hoping for some luck.   I wish you luck, I DO !  Boycotting Amazon, now. (due to not showing shipping country !, the H3LL with that)  3-1-2015 edits. added fancy shopping searches.