ZARTT

1995 4Runner 3VZE 4x4 A/T.
Check Engine Light does not come on when ignition is switched on.
(I think that is the main clue.)
Good battery voltage to ECU. Good ECU. Good CEL bulb.
Good ignitor, good coil, good battery, good cranking.
No spark, no pulses to injectors. No start.
No CEL, so can't pull codes.
Fuel pump runs when key is turned on.
Also pump runs when fp is jumpered to b+.
All fuses OK. Circuit opening relay is OK.
Distributor has been swapped, and all wiring from ECU to distributor, ignitor, and coil has been checked OK for continuity and grounds.
I need some educated guesses.
I'm kinda at the end of my rope.

Art.

hunter4runner

IGN fuse in the drivers side kick panel FTW

iamsuperbleeder

possibly

else the ECU is gone

ZARTT

All fuses, including the ign. fuse, checked OK with an ohmmeter.

ZARTT

ECU was swapped out with a spare from a running vehicle.

hunter4runner

change it anyway its a 15amp right ? IIRC if not then is the AFM hooked up correctly ?
If the AFM has an internal short than it will do this

sb5walker

CEL runs off the Gauge fuse, I think, not the IGN. Make sure the gauge fuse is hot when ignition is on - it supplies power to the CEL bulb and the ecu grounds it. If you need a new bulb, it is either a # 194, which has a wedge base:



Or a # 74, which also has a wedge base:



I think the SR5 clusters use the 74, but not 100% sure. Any decent parts store should have the bulbs; NAPA does for sure.

If you need to change the bulb, this thread may help you get at it:
https://www.yotatech.com/forums/f116...w-pics-179106/]

hunter4runner

in a 95 4runner if the IGN fuse blows no CEL and it wont crank ask me how i know lol

iamsuperbleeder

how do you know?

hunter4runner

it happened to me once after working on my truck all weekend and freaked out like a little girl

iamsuperbleeder

lol, oh okay


I had to ask; you told me to

hunter4runner

haha i figured someone would lol

ZARTT

The CEL bulb is OK. I got it to light by probing the wire in the ECU plug with my test lamp and grounding it through the test lamp bulb. They both lit up.
I have swapped out ign, and the gauge fuse. All the fuses under the hood are new.
The ECU is properly plugged in, all three plugs are different sizes.
I need more guesses, one of you will hit it, and the idea light will go on. (no pun intended)

hunter4runner

you just said "all fuses under the hood are new"

I'm talking about the fuses in the kickpanel inside

and if not check the afm

ZARTT

The sentence should have read "ign, and gauge fuses in the kick panel were changed, also all fuses under the hood were swapped out".
My buddy is letting me use his identical 95 4Runner as a parts bin, so I will swap out the AFM tomorrow. Good call. I'll report back tomorrow night.

Art

hunter4runner

ok cool let us know

bugs1961

Look at the last page of this PDF for a troubleshooting guide of the check engine light: http://www.ncttora.com/fsm/1990-1995...e/diagnosi.pdf

This page (15) shows the schematic of the system and what fuses do what. The gauge fuse powers the bulb itself and you said it works. The IGN fuse powers the operation of the EFI main relay, and if bad, will give the exact symptoms you describe. The EFI relay failing will also cause the symptoms. You can check for power at the ECM on the +B and +B1 terminals. If you have power there, the IGN and EFI relay are good.

If you can confirm power from the EFI relay, and the CEL illuminates by grounding the W terminal of the ECM, then the only other possibility is the ECM is bad.

You should never use a test light on the ECM or any sensors controlled by the ECM. The ECM operates on very low current and can easily be destroyed by the relatively high current that flows through a test light (and the ECM in the process). Only use a digital multimeter. Even an analog meter uses too much current for the EFI system, unless specifically called for on a test. All tests of the ECM assume the use of a digital multimeter.

Good luck. The most common causes are the IGN fuse or EFI relay. Hopefully the ECM isn't damaged.

ZARTT

I have taken the ECM from my Runner and installed it in my buddy's identical car. The part numbers are identical. When I switch on the ignition the CEL illuminates. My suspect ECM runs his car. I can jumper for codes in his car, and observe the evenly spaced CEL flashes that indicate "no codes posted".
When the suspect ECM is back in my Runner, it acts dead. The CEL does not illuminate when the ign. sw. is turned on, and I can't pull codes.
The ignition switch is good, the circuit opening relay has been swapped, the MFI relay has been swapped, every fuse inside the cabin, and under the hood has been changed.
Using the 4Runner 1995 FSM,and a high impedance V.O.M. I have checked every point to point wire in the ECM circuits for continuity, voltage feeds and grounds. (where they shouldn't be.)
All check out as good.
I have checked all grounds. (where they should be)
I know the CEL bulb is good because I can light it by grounding pin W (A-5) of the ECM.
I have 12 volts at the BAT (A-1) wire of the ECM, all the time, and 12 volts at the B+ (A-12) wire when I turn the ignition sw. on. This is the same as my friends Runner.
I am up against the wall.
All my diagnosis says that my ECM is dead, but yet, it runs and acts normal in my friends 95 Runner.
Any suggestions that uses tea leaves and tossing chicken bones in the air will be given serious consideration.

Thanks
Art.

hunter4runner

did you swap the AFM?

inside the distributor there is a signal pulse generator or something has that been checked

ZARTT

I have swapped out the AFM, and the distributor from my friends 95 Runner.
My friends car runs OK with my distributor, AFM, and ECM.
I have come to a halt because I don't know what to do next.

Art.