USA- Jeeps   

Show Stoppers? (My get out of deep trouble, page)            Need Jeep parts, or what parts drawings (p/n) etc?

Did you check all fuses first?

 The Innova 3140 scan tool can scan these 3 , OBD1 years.
1993 to 1995 ALL DTC errors from FSM.

History matters (USA) OBD1  was mandated here in 1988 in only  California laws, then 1991 federal EPA law kicked in) (by LAW for all main States)  Calif has California, Air , resource board (Cal, EPA) or C.A.R.B for A.R.B, for short.
 The PRE-OBD systems have no CEL lamp in the cluster nor DTC flash codes, nor scan tools sold until 1993,  other than $2000 + DEALER  DRB + tools and others, very expenisve tools.
These Jeeps below, have no over the counter scan tools sold.. until 1993. Renex is pre-OBD ! (aka, by me, as brain dead ECU's) "no monitors for driver to see = brain dead"
The more early Jeeps had (XJ) French RENIX EFI  funky (IMO) systems. (no CEL lamp , no flash codes ECU's)  For sure this is the first Jeep digital EFI system...  ( there are lots of more early analog VW EFI systems)
nor  the AMC (yes, American motor company) ECU on the  YJ,  the 4.2 L AMC 258 I6 until 1991  some had an electronic CARB, with carb ECU !. (no small horror there)
The AMC 2.5L  AMC 150 I4,  is better and  had  TBI injection system. (real) the 4.0L (before 1991) was RENIX horror system.  (I ran 3 , of these then (1988's) and know most the  horrors related)
The Renix list:  by Renault
Model years:
  • 1986 - Renix TBI available on Jeep 2.5 L four-cylinder engines.
  • 1987 - The new Renix controlled 4.0 L six-cylinder engine was rated at 173 hp (129 kW; 175 PS) and 220 lbft (298 Nm) of torque.
  • 1988 - 4.0 L output increased to 177 hp (132 kW; 179 PS) and 224 lbft (304 Nm) of torque, due to higher compression ratio.
  • 1989 - Changed to Renix MPFI.
  • 1991 - Chrysler Corporation (then the owners of the Jeep brand replaced the Renix control system with OBD-I-compliant control electronics, the Chrysler HO EFI).
The Renix is a good system when it works,  and has closed loop oxygen sensor, and is MAP based , speed density system.  The MPI is better than the TBI. (in all ways) but they all lack flash code DTCs...  call it OBD-0.5...  (1/2 done or  1/2 baked...)
First seen in 1984 on Renaults of Europe...
Starting in 1993 we now can use off the shelf scan tools and starting in 1996 , all scan tools work here in USA. (1998 in Canada)
My RENIX failures. (exhaust manifold cracked over and over,  rendering the 02 sensor useless and bad smog and wasted fuel) the CAT love to break  up inside and turn to dust (guts go bye-bye), over and over.(failing smog tests for sure)

This section is for driver safety: ( the prevention of 4WD drive line bind up /windup)
Windup is very dangerous to you and car,  , using Part-Time 4wd  on dry pavement (dry means, no ice/snow)   to you and car. (and others as you skid out of control). 
It also means not to use in on only rain wet pavement ! 
At the least , you risk damage to the Transfer Case  Chain drive. (stretching that poor chain is not a good idea, for sure!)
drivers, never bother to read the operators guide  and any driver that does not know the transfer case make and model.# might make this mistake.  LOOK HERE FOR VISUAL I.D.
To exit this mode/ BINDUP , say you messed up and are in PT 4WD on dry pavement, move car gentle turns, to a  slippery surface,  (ice, snow, dirt, grass, gravel,sand or side of road that is loose dirt, or sand over pavement yes, any thing that slips,and put the transfer case back into 2WD or 2H.
Related, issues, is 4WD light stuck on ,or fails to light in 4WD (do the lamp test yet?)
If stuck in 4WD, drive too any off road, dirt, sand, gravel, grass area (or ice/snow) and shift back 2WD, and then move car forward, until light goes out.  The transfer case can freezes it's shifting forks (and silly light), when bound out. (wound up) , so unwind it and win.
There is no need for 4wd light, you can feel 4WD,  and for sure of you turn on dry  pavement, that odd fell is the windup and damage you are doing to the drive train, its a warning, hey buddy, you messed up.  Read the manual for your car, don't lose it. or mix it with others.
Some jeeps with PT 4WD have a viscous coupling that stops this damage, most jeeps, don't have this, and for sure not my 2008 Wrangler X.

For fun read what Suzuki says to do at windup time, Dang funny stuff .  Like a Fire Drill funny with jacks.
All most all transfer cases have  tag on the back telling you ,what it is, so just look first.

The ability to avoid wind up, is done by 3 magic words,  1: AWD all wheel drive, 2: I have a center differential and last 3: I have a center slip clutch (aka: viscous coupling)
Do not use Part time, or  AWD LOCK mode  or 4LO  or (old) Emergency mode, on dry pavement  if your shifter selector offers this features.
In all cases, read you operators manual first.

Jeep current systems:
Command-Trac:   Part-Time 4WD or PT 4WD.
This is  PT, it is a system, that has  No center Differential and this means:
Stay off dry pavement, or  water wet only pavement.
PT is for driving off road,  and on roads with ice or snow, only.
PT needs  1 tire to slip, at all times.   (as does LOCK and 4LO)

Select-Trac Introduced in 1973   (some  have PT modes) The number below are "New Process" (or "Venture Gear") transfer case numbers.   To know what your case can do (all 28) , is best seen here at WIKI.
Lots of early transfer cases were used. This list is not complete. First is Borg Warner.
1973 BW1339 This unique  and tough transfer case, had an integrated limited-slip center differential much like an axle of same name, that transfers power to the front and rear axles. It has PT and FULL time modes and a vacuum operated e-LOCK (parts are hard to find)
Do not use the e-lock on dry pavement.

1983 to 1991 , NP229 case uses the viscous couple, anti-windup  features. has 2WD and Low range selector.
NP119 transfer case in 1980, a strictly full-time all wheel drive model (no selector options)
1981 to 88 Select-drive NP129,  Full time with 2WD selection and  with viscous coupling.
The NP128 is  Full time. open diff.
1986 NP228  same as 128 but with low range. and higher duty.
1987 NP/NV242, is full-time all wheel drive AWD (and PT selectable as an option, so don't use PT or lock or 4Lo on dry pavement.)

All the below systems can  run on dry pavement, but not LOCK mode or 4LO mode.
Quadra-trac was introduced in 1973 the  using
BW1339 . (full and Part time selector modes)

Quada-Trac is full time 4WD (not in lock mode seen in 1975 RED side here.) has a real center differential to shift torque between front and rear.   The 1993 lever is seen here,  and do not use 4LO on dry pavement.

Quadra-Trac-II  NV 247 Gerodisc system  1999+  "4-All Time", "N" or neutral, and "4-Lo". In "4-All Time", torque is applied to the rear wheels under normal driving conditions.   Do not USE 4-LO on dry pavement !
If the rear axle starts rotating at a significantly higher rate than the front axle, hydraulic pressure builds up in the gerotor oil pump and causes the clutch pack, to progressively transfer torque to the front axle, until both axles return to the same speed

Quadra-Trac I  NV147 was introduced in 2004 , same as above, but is automatic all the time,  with no driver 4wd controls , like above. No N, or  or 4LO, like above.  Just drive.

The Quadra-Drive NV247  system was introduced in 1999 and is based on the Quadra-Trac II system but adds LSD limited slip differentials (the best full time system ,with great traction to all wheels all the time) 1999 to 04.
Quadra-Drive-II  has electronic limited slip differentials or ELSDs 2005 up.
Newer systems 2007 and up are here. and are all full time 4WD

In every case, read your operators guide that matches your system, as your car was fitted out day 1.  RTM read the manual and heed the warning on pavement in 4Low and locked. 4Low and locked is NOT for dry pavement.
If you are running part time (lock, 4lo ) 4wd , one tire on the car must be on a very slippery surface, to run safely .  (ICE/Snow or dirt, sand, grass, snow)

If you car does not have LSD Limited slip differential axles, and one tire slips? Drag the foot brakes gently and get a poor mans, LSD. Try it, you will be shocked at how easy this is to do. and get you out of a jam on ICE or one axle/tire on ICE.
My 2008 JK does this in the PCM computer via the ABS system , automatic virtual LSD it has. (just software to do that using existing hardware (ABS))

Smart display options on newer Jeeps: (or EVIC)

EMIC is fancy dash display and VFD is cheap display (vacuum florescence display) in the CLUSTER.   My INNOVA 3160 scan tool can in fact, scan my JK Jeep and tell me the door that failed to lock. (it does all factory codes)
In all cases of trouble , read the FSM on topic,  get one , buy one , or use or the First links at the top of this page.

Body Codes:  Some history here.
Jeep History helps.
The marque has gone through many owners, starting in 1941 with Willys, which produced the first Civilian Jeep (CJ).
Willys was sold to Kaiser in 1953, which became Kaiser-Jeep in 1963.
American Motors (AMC) bought the company in 1970.
The Chrysler Corporation bought out AMC in 1987, shortly after the Jeep CJ was replaced with the AMC-designed Jeep Wrangler or YJ.
Finally, Chrysler merged with Daimler-Benz in 1998 to form DaimlerChrysler.
and now is Fiat in 2009.
They did continue to use "AMC" parts until the stock was depleted.

CJ / From the beginning of time until 1986  (means Civilian Jeep)
YJ / 1987 - 1995  The original Wrangler
TJ / 1997 - 2006   The second generation Wrangler (owned 1)
JK / 2006 to date   The third generation Wrangler  (with 16 computers with CAN and LIN bus)  JKL = 4door.  (I have one 2008 2dr, 6sp M/T)
XJ / 1984 - 2001   The  Cherokee (I owned 3)
ZJ / 1993 - 1998   The Grand Cherokee {lets call it GC}, the JG is Export models produced at the plant in Graz, Austria. (for Europe +) and WH, ZG, WG. You can wiki them.... and are made in China too.
WJ / 1999 - 2004   Second gen  GC.
WK / Since 2005   Third Gen. GC.
XK / Since 2005    The Commander
KJ / Since 2002      The Liberty (called Cherokee outside USA, very odd that)
KK/ Since 2008      Second gen Liberty.August 21st, 2012 (mfg date end for 2013)
SJ / Full size Jeeps (Wagoneers) 1963 - 1991
MK is       2007 + Patriots
Jeep  does use special body codes, for Export models. (and for sure RHD cars, "right hand drive")


DTC errors?   Diagnostic Trouble Codes (a.k.a: Cave man flash codes for cheap skates , not using real $5 scan tools)  EFI means Electronic Fuel injection.
The EARLY cars have OBD1 PCMs; pre 1996 , USA
(OBD2 cars started in 1996 by mandate , here in the USA ) (full cheap scan tools are sold, dirt cheap , buy one and stop guessing , please)

The old and "dirty" 1988 to 92 EFI Renix French system ,  old XJ systems, have no tools or flash codes,, that is because they are not OBD systems at all, but AMC Renix. unique queer system  is not OBD rated,! but Jeep has  special tool for it, mostly dead, bad, lost or missing today.
To read OBD flash codes, 1993 to now.
You only need to do the key  on/off dance,  (does not help find all DTC errors, not at all , this trick only finds simple engine controls errors, and is never used by any pro shop with real tools)
This trick can miss 2 reasons for ASD drop outs.  ( a travesty to you, if engine stalls due to ASD drop out)  See ASD link above.
The tactic is only good in emergencies, far from home and zero tools. Not using real tools? you will miss the BOAT,  "Sailed Away"
Models - 93+  (my 2008 works JK)
Start with the ignition off. Within five seconds, switch the key on, off, on, off, on. ("On" is NOT "Start" and "Off" is NOT "Lock").
The "check engine" light will flash. (codes)
Count the flashes. Each code is a two digit code,for example,23 would be FLASH FLASH (pause) FLASH FLASH FLASH (long pause). It may flash out up to 9 codes.
The best  tool for 93 to 1995 is the INNOVA 3140 tool for OBD1 (with adapters) Bang for the buck, best.
Starting in 1996 all  modern generic scan tools work , even new $5-10 USB OBD2 tools work, and see all engine /trans codes (but not ABS or Bags)

The 1998 and newer Jeep Cluster self test. Yes, the cluster is a computer (brain) yes it resides on a real network called CCD.

The instrument cluster actuator test will put the instrument cluster into its self-diagnostic mode.

In this mode the instrument cluster can perform a self-diagnostic test that will confirm that the instrument cluster circuitry, the gauges, and the PCI data bus message controlled indicator lamps are capable of operating as designed.

During the actuator test the instrument cluster circuitry will sweep each of the gauge needles across the gauge faces, illuminate each of the segments in the Vacuum-Fluorescent Display (VFD), and turn all of the PCI data bus message-controlled lamps on and off.

Successful completion of the actuator test will confirm that the instrument cluster is operational. (only it and never prove communications to it are good)


Parked not moving. Both cluster fuses not burned out.(as seen in the FSM books on all Jeeps)
Begin the test with the ignition switch in the Off position.
Depress the odometer/trip odometer switch button.
While still holding the odometer/trip odometer switch button depressed, turn the ignition switch to the On position, but do not start the engine.

Release the odometer/trip odometer switch button.
Monitor the operation of the suspect gauge(s) and/or indicator lamp(s).
The instrument cluster will automatically exit the self-diagnostic mode and return to normal operation at the completion of the test.
 If the ignition switch is turned to the Off position during the test, or if a vehicle speed message indicating that the vehicle is moving  (not 0mph) is received from the PCM over the PCI data bus during the test, the test will be aborted.
This does not prove the CAN-Bus works perfect and that the PCM can talk to the cluster brain.  (the PCM will tell you that, problem, if you just listen to it (DTC errors P16xx),  by using any scan tool made (modern) !
If data in the cluster is wrong, scan the PCM using any scan tool that does Canbus.  (all modern tools do, even $5-15 tools sold on fleabay)

The best tool , in my opinion (DIY) is the INNOVA 3140 is best tool (hand held) for 93- 96 jeeps or 3160 for all  later years.

If the Cluster can not hear (comm's dead) the odometer readings from PCM the CLuster freezes it to last know mileage, last time  all this worked right. (so says FSM, read it , it very good that book)

Parting shot: 
The stupid blink codes key on/off method, loves to hide the very code you are trying to see..   (CMP/CKP or Spark fails are autocleared. on most cars) So, get a real scan tool and stop guessing.

4WD = Four wheel drive
AWD = All wheel drive.
2WD,  sure  easy. (you can guess this.)
EVIC= Electronic Veh. info Center.
Electro-Mechanical Instrument Cluster
VFD  = Vacuum florescent Display ( funny blue or the aliens landed green eary  glow)
FSM = factory service manual  (seen for free at top of this page)
OBD = on board diagnostics.  (means the brain, looks for error all the time and finds them full time, running and reports them)
LSD= Limited slip differential axles
Center Diff, that magic, differential GEARS, in the center of transfer case, that allows the front of car to move faster than the rear, (1/2 joking) it allows the front axle to move independent of the rear and not BIND UP the whole system as PT does.
PT = Part time 4WD.
SKIM =Security Key Immobilizer module. 
VTSS = Veh, theft and Security system.
ASD = automatic shut down , relay.
TPMS = tire pressure monitoring system (from HELL)  My car will not tell you which tire fails, even with top brand $$$ scan tool.
 Unless you have my TPMS scanner or on the dash cluster,  you have the Electronic Vehicle Information Center (EVIC)  btw , this system is dead, with IOD fuse pulled and will log , DTC errors.

Rev 9   ++++ 3-27-2014