Why does my ECU click the relays madly, or blow FI fuse?    
  clicking , clattering , buzzing , or  making a racket.
The MAIN RELAY and the FUEL pump relay,  (main clicks 1 time Keyon , and FP relay 2 times, is normal.  {89/90 FP relay will not click key on.})

Classic cases; beside the green death  acid spills shown Here...  ( yes, bad CAP's in the ECU will cause clicking and a bad ECU for sure and the below too.)
First is to say what is clicking? find it and get help.
Macro reasons:  
  • A BAD ECU  (89-95 only)
  • ECU  external input to ECU  power buss is overloaded  12vdc is too low, below 11vdc. 
  • The ECU  has shorted sensors or actuators.

Actuators are, VSV , relays and injectors.  VSV means Vacuum Solenoid Valves. (Dashpot, Evap, and EGR)
To find shorted devices, unplug them or use any DC ammeter , amp clamp to measure live current.  (the latter is the best way)

Check all 3 fuses that power (see end )  the ECU for corrosion and full power to the ECU 12.6v DC. Battery must be charged.!  check the FI , Dome and IG-COIL fuses.
Micro Reasons:
  1. ECU just plain BAD ! (lots of ways inside) or the infamous (89-95) bad electrolytic capacitors failed "The Rubycon  disease."
  2. Power feed to ECU is bad. (or overloaded)    The cars, main or sub main fuse box has weak power due to corrosion. Or bad ground straps on the car.
  3. The 0² oxy , sensor likes to short overloading ECU or its power source. disconnect it or replace it. The burned up wires near or shorted O2 sensor can overload the ECU.  Common !
  4. Fuel pump is shorting ( or its power feed wire is grounding out ( or pump is  drawing way over 4 amps normal draw , a bad pump can overload an ECU)
  5. ISC Coil shorted.  (on throttle body or plenum)  (89/90s are low as 6 ohms , others are 15)  Unplug it. (no more clicking?)
  6. VSV's coils shorted.  there are qty, 2 to 5 VSV vacuum solenoid valves on engine. (unplug them, does clicking stop?)
  7. After market Cruise control  hack jobs to the EFI system.
  8. Audio wiring gone wrong ( truly limitless hacking potential here , find the violations and correct them)
  9. A bad  MAIN or FP relay. (they have same PN , swap them ) PN=part number.  FP = Fuel Pump.  very rare.
  10.  SHORTED harness wiring  anywhere associated with EFI connections. (look carefully at both ends, ECU and actuators at all harness ends !)
  11. The ECU CAP'S can in fact be bad, and will cause the ECU to reboot over and over, causing the clicking each boot up.  very very common.
  12. There are up to 13 paths of power load, at the ECU, that can overload the power buss of  the ECU.  
  13. If Main is clicking we see the D102 (8v nomenclature) is cracked and open and touching and arching and sparking.  
The ECU power schematics are shown here for 10 years running.

The Fuel Pump relay likes to  click  due to pump overload ( relay has  pink pump wires , ) FP relay may have a green socket.
The VSV solenoids like to click  too.  ( usually this means ECU is booting up over and over )
The MAIN relay next to it only clicks if it is bad or the ECU is bad or ground to ECU is lost to ECU, both Relays are below ECU 91 to 95.
On 89/90s the FP relay and MAIN are integrated and the pump only activates cranking on this year (see my 89s pages)
These two relays can be swapped. Main and FP. (91-95 at least)
Check all inputs and output voltages on the ECU and make to be  sure  no coils connected to the ECU are shorted,   10 to 40 ohms are typ. values. (cept 89/90 low ISC coils)
Use of an AMP CLAMP AMP meter can make testing here a breeze.
The Tactic of  unplugging things can find a bad DEVICE.
Start by unplugging fuel pump at LR tail light housing (pink wires)  ( or use meter to measure pump current)
To me , I pop the lid on ECU first, look for bad caps. ( Look carefully and for Rubycon name, if these are present I get them out pronto)
Look for green acid spill  (ignore the cream  colored conformal water proofing) bulging caps, cracked , and a good meter has a cap tester so test them (removed).
Look for black soot under ECU LID? , acid spills and Caps cracked , exploded or leaking or any damage at all to them, and they can look perfect and not be so.


All the above applies if you keep blowing ECU fuses (any of the three)
Things that wont cause ECU overload , ECU clicking and relay buzzing and fuses to blow are, ECT, IAT.
A shorted MAP of MAF will trip the DTC error but  don't think it can cause the clicking.

The ECU caps like to short and blow the FI fuse.

Normal clicks:
Key on MAIN relay clicks once, and never buzzes or clatters.  it unclicks at key off.  
Most if not all VSV's  click 1 time , key on , because many are defaulted to open , with no power. so the ECU activates them at key on , to close them  up.
The Dash pot ,  EVAP and EGR, VSV' valves , all click 1 time. Key ON. and one more time, key off.
The Fuel pump relay clicks: when?
89/90 cranking only. and holds closed running. then unclicks (deEnergizes) key off.
91+ Kicks, the FP relay click on for 3 seconds, key on,  (2 clicks, 1 for ON, and 1 for off)  (Suzuki Sports, my need to be cranked if  the ECU is unflashed buy TSB order)
The FP relay stays closed while cranking and running on all cars. (as long as spark is good)
The fuel Pump buzzes anytime it is on , so buzzing here is quite normal.

The Dash pot VSV licks after first 10seconds running and releases the dashpot and drops RPM greatly.
The  EVAP runs only moving.  so it clicks at keyon (closes) then opens (clicks) 1 time as you cruise.
The EGR is more tricky,  it closes key on, then only opens (clicks again.) cruising or racing the motor , after 1993 the EGR only opens moving.
The EGR will click if you go to W.O.T (wide open throttle, is over 75% throttle .)  
If the 93+ car , TPS fails or VSS  fails or goes crazy the EGR will go  crazy with it.   The TPS must signal not at idle cruising and the VSS must say you  are.  VSS = veh. speed sensor.

On 1996 and newer Sidekicks the EGR 2 relay (rear of plenum) can click a few times during the running OBD2 monitor of the same.  
On 1997 and newer Sidekicks the newer EVAP 2 system can click at all times.  it is a very complex system and runs complex OBD2 monitors, when running.
Do not hot wire your injectors.  The 8v  injector has a 1 OHM coil, hot wired, that coil receives 144watts of energy, burning it to a crisp (use the pulser shown in the FSM)  Imagine holding a 100watt light bulb.  Dig?
The 16v Injector uses 12 ohm injectors.  Ohms law:  P = V² / R     12.6v squared is 159 / 12 = 13 watts.  This too, can get hot fast.  Don't do it. Use the pulser like the FSM demands.
Why compound your errors by burning up the good parts.  Or compounding it, to blowing up ECU .  
Coil readings in Ohms.

EGR1 front VSV  =  32ohms,  EGR2 rear = 31 ohms all other VSV =  27 ohms

Main relay or Fuel pump relay  = 135 ohms.

TCC relay = 100 ohms.

ISC valve = (89/90 = 6 ohms,  91'yr + =  12 ohms

Fuel pump current is about 4 amps.  (filter not clogged.)

Jargon.

rev 1   ++++ 3-12-2011