This is badass thank youYou can make a test light. Find the smallest lightbulb and socket you can in the truck that works and you can take it out, including the socket. Cut it out of the harness, leave enough room to splice it back. Try to find a bulb that has other bulbs like it in the truck that you can get to in case you short it out and burn up your bulb. Don't use this as a jumper wire, it's just to find juice. Jumper wires can be speaker wire, wires from a smog solenoid, tail light, turn signal, horn wire etc.
Turn signal bulbs and tail light bulbs draw quite a bit of juice and may damage ECM components but they will work to test primary feeds, fuses etc. Add wire from something you can live without, like a speaker, to get test leads long enough you can use. Insulate splices if you can, so you don't short them out on fenders etc. Paperclips, screws, soda can tabs, all work to make ends for the wires you can use to probe and test with.
Start with the power to things that make the CEL work. From that list, I pasted the things that you can do without an OHM meter. My apologies if this violates some protocol but the cause is worthy.
Diagnostic Procedure for 1991/1992 3F-E EFI Related Issues
Motor not running; key in ON position;CEL, A/T, CHARGE lamps should be on. No CEL=No StartThe EFI circuit is initiated from the ECU (E5-pin 3) which energizes the EFI relay coil. The load side of the EFI relay feeds +12 to the ECU (EFI on logic), all 3 VSV valves, both O2 sensors, the ISC valve, pin 8 (B+) on the DIAGNOSTIC connector, and the load side of the circuit opening relaywhich feeds the fuel pump.
All EFI related +12 comes from the 15 amp EFI fuse in the under hood fuse box. This fuse also feeds constant B+ to the ECU. The CEL (CHECK ENGINE LIGHT) is illuminated by the ECU with a logic low on E6-pin 8 and should alwaysfunction as described. In other words... No CEL=No Start.
The most common cause of a no-start is a failed fusible link, Toyota part# 90982-08264Below is a cursory check of all 3 fusible links in system. This assumes an unmolested OEM configuration.
FL AM1-Dome lights working?
FL AM2-When you turn the key to ON does the CHARGE LAMP light up?
FL MAIN-Brake lights working?
If yes to all 3, then all 3 fusible links are intact.
* A short or damage inside the AFM can cause the CEL not to illuminate. A short or damage is usually the result of removing the 2 Phillips screws on the connector housing when trying to remove the connector. Do not remove the screws.There is a thin spring steel clip that you just need to push up. A quick AFM diagnosis is to simply unplug the AFM connector. If the CEL now illuminates, the problem is internal to the AFM.
* Proper operation of the AFM will shut down the fuel pump when the air flow flap closes. This ensures that in the event of an accident/motor stall the fuel pump is not running even with the key in the ON position. There have been several reports of folks being able to unplug the AFM connector and the truck continuing to run. THIS IS WRONG AND POTENTIALLY LETHAL. Look into the CIRCUIT OPENING RELAY in the left kick panel and test associated fuel pump logic. Motor not running; key in ON position; CEL, A/T, CHARGE lamps should be on. If ALL 3 are out, check IGN fuse and fusible link AM2 or ignition switch.
"Motor not running; key in ON position;CEL, A/T, CHARGE lamps should be on. If no CEL then,
* Check for +12 VDC on brass terminal screw in under hood fuse box. This terminal is located directly to the left of the main fuse and is a Phillips screw head.
* If no +12 VDC in fuse box, then check fusible links off positive battery terminal. 2 to the black plastic junction box and one to the connector.
* If +12 VDC in fuse box and no CEL, then suspect EFI relay/fuse and associated wiring and contacts. Many have said that the wire from the EFI fuse to the EFI relay is undersized and is the root cause of all these problems. I disagree with this. At 2500 RPM I measured 6.25 amps across the load side of the EFI relay contacts. I believe the cause of the problem is related to the heat of the manifold combined with poor crimps on the connectors in the fuse box. Over time these connectors can become corroded and resistive.
* Check for +12 on pin 8 (B+) on the DIAGNOSTIC connector mounted on the right side of the fire wall. If +12 on pin 8 and still no CEL, then EFI circuit OK and problem is with ECU or related wiring."
Coil/Igniter:The coil/igniter are mounted as a pair on the right front fender next to the cruise control actuator. If CEL is ON and no spark from coil, then possible coil/igniter failure. In the FSM there is no diagnostic procedure for the igniter. These can become intermittent and the only course of action is to swap it out with a known good one. Both the ignition coil and igniter are grounded through the mounting bracket. It must be secured to the body.Distributor coils can open or short but are not a common failure. Be certain that the distributor pickup coils are hitting the ECU. G (E4-pin 18) NE (E4-pin 4) G-(E4-pin 17)
Some notes on fuel pump operation:
The fuel pump is fired by the CIRCUIT OPENING RELAY and its 2 logic paths, left side kick panel, bottom center below the relay block.
The primary relay coil is energized from the STARTER circuit when cranking the starter.
The secondary relay coil is energized when the flap in the AFM opens after the motor starts sucking air.
For diagnostic purposes only,you can bypass all fuel pump logicby shorting pins 1 (FP) and 8 (B+) in the diagnostic connector mounted on the firewall. This will force the fuel pump to run with the key in the ON position, assuming proper operation of the EFI circuitry.
PINOUT of DIAGNOSTIC CONNECTOR:
Firewall side of Diagnostic Connector
Cover Hinge Side: TT(17) / TS(16) / OX2(11) / VF2(10) / VF1(9) / B+(8)
TC(15) / CC2(14) / BLANK / TE2(7) / TE1(6) / CCO(5)
OPT(13) / AB(12) / OX1(4) / E1(3) / W(2) / FP(1)
The diagnostic pins are hard to access. A paperclip works but it's hard to make a good connection. Best is a blade connector from a crimp on type wire connector, you cut it roughly in half so the blade part is only 1/2 as wide as normal. That allows you to make a good connection. In a pinch, you could probably bend the end of the keyring straight and use that to probe the connections and attach that to your home made jumper-wire.
If you are too low on fuel, it will pump air bubbles into the lines. Bubbly fuel won't work an injector. You can compress it as long as the pump is on but when the injector opens, all it shoots in is compressed air and a tiny bit of fuel. The fuel pump itself is under the rear seat if I remember right. You should be able to hear it running when you do the jumper wire trick in the connector to bypass the circuits and turn on the pump. If you can't hear the pump run, it might be dead. Sometimes you can get them to work by banging on the bottom of the tank hard or the lid where the pump drops down into the tank while the wire is hooked up. If it starts running after you did that, you have a bad armature in the pump. As soon as you take the juice off that pump, it's going to stop and probably stick again in the same spot. The same trick may not work twice to get that pump to run.
The pinout gets fubar'd when I post the thread. You'll figure it out if you use that guide he provided above and correspond it to what I typed.
Huh?You either have no drive, or your tryin buy it yourself. Or you dont have kids, or your a rich kid, or your not German. If I gotta rebuild it I'll rebuild it. I've never tried to fix something and failed in my 38 years on this planet. Except relationships with women. That's the s*** that keeps me up at night. Lol. Trust when I say I'll have her up and running here soon.
Easy there big fella. Have you ever heard of context?This guy's gotta be a troll.
I mean, I'm all about helping as much as possible when RTH flag is raised.
And while the 3FE is out of my wheelhouse, we're all here hoping to learn as well for whatever worth it may be in the future.
Dude got the best 3FE help in the country he can get for free, imo.
Just can't help but think he's a troll. And I'm even on his side when it comes to (some) women. lol
Might be some useful info for you in this thread.Is having an broken " cold start injector time switch" my issue ? Still no cel.