[SOLVED!!!] What's the strangest reason your truck wouldn't start? (Yes, I need help)

Update for today: Still no running engine.

I tried putting starting fluid into #1 & #2 cylinder, as well as the throttle body. Crank, no spark.

I bought a Noid light for testing fuel injectors. While all of the lights in the box seemed to be for Ford or GM engines, one of the GM lights fit the socket for the Toyota injector plug perfectly, but when cranking the engine, nothing happened with it. So, what does this mean? Who knows. It means either that Noid light test kit is incompatible with Toyota injectors, or I have both a spark and an injector problem. This has only created more doubt/questions. I also tried a multimeter on #1 injector plug while cranking and it read 00.0 volts the whole time, without flinching. This could be due to the limited amount of time the injector opens, or because there is no pulse to the injector. Like I said, more questions now than answers. I know there is a stethoscope test you can do to listen for an opening injector, but I am unfamiliar with that, and have no stethoscope.

I guess I'm down to doing a pinout at the ECU harness, end to end. It's going to be painful, but seems to be the last resort at this point.

 

The noid light should blink. Fuel injectors typically have one of the wires getting 12 V positive with the ignition on and the computer grounds the negative side. You can check for 12 V positive voltage on one of the injector connectors to see if you were getting power to it. If you do, the computer is not pulsing ground on the other wire. If no 12v +, then trace out why. With no injector pulse or spark, it sounds like a wire harness/computer/pinout problem.

 

Understood. With the injector connector removed, negative probe on the battery, I get +12.8v on both injector harness leads with the key on. When cranking the engine over, voltage drops to around +11.6v on both leads (tested separately, one then the other) until cranking stops, then back to +12.8v. So, this leads me to believe more that the Noid light was incompatible with the Toyota system and the drop in voltage is the result of the signal being correct, but being so short that it doesn't drop to zero. But does this mean the injector is pulsing? I don't know. I would think I could smell/feel fuel on the plugs if the injectors were working properly, but I also don't know that the injectors fire onto the plugs or more downward into the cylinder. It makes more sense that the fuel would go more into the cylinder than directly on the plugs--I have just had others suggest that the plugs would be "wet" if the injectors were pulsing.

 

The voltage may be dropping just because of the big current draw from the starter.

How about checking for the proper signal the ECU sends to the igniter to trigger the spark? You may need an oscilloscope. The Toyota repair manual probably shows how to test.

You can also check cam/crank sensor signals with an oscilloscope while cranking. The computer might throw a code if there was a problem with not receiving either of those signals while cranking, whick suggests these are less likely to be the problem.

I would work back from the distributor. Check for proper signals from igniter to distributor. Then from ECU to igniter. Then if no signal check the pinout. Then check cam/crank signals.

 

I forget the Battery was removed from the Truck

 

I should’ve clarified that to check for voltage at the injector, you need to unplug it. The reason you’re getting 12 V on both sides is because there’s no pulse ground from the computer. Typically a GM NOID Light Should work in your connector plug. Just make sure the two pins are touching the metal connectors in the injector side of the harness connector while the injector is unplugged. Also if you have a regular 12 V test light with a light bulb in it, you do not want to use that to check any computer wiring. You either want to use a Digital volt/ohm meter or a specific high impedance test light. Otherwise you can burn computer components out unintentionally.

Again I believe that there are wires crossed somewhere in your main harness connector or computer connector being that different years and computers are used. I would try and find computer connector pinout diagrams for both and comparing wiring locations.

 

Come on, already! You’ve tried another ecu?

 

I unplugged the injector before testing the signal with the Noid light and the meter. I guess I can check the operation of the Noid light and rule than unlikelihood out. But I think you are right. I think at this point it's got to be an ECU, which sucks because of the cost. I got a reprogrammed "new" ECU from FS1 that came with the additional connector for the automatic transmission, which I do not have. I have no faith it was programmed correctly when they can't even give me the correct ECU (manual transmission). So, plugging it in and getting no spark and a flashing Check Engine light when cranking, plus a non-read from the OBDII tells me that it is useless to me at this point. So, a Pin-out and then maybe another ECU when I can afford that.

Other than Ebay (which is where my first ECU came from), does anyone know of a reliable reprogramming company? I'm hesitant to try the scrapyard in the San Diego area. Prices are likely higher than Ebay and just as unreliable. FYI - Flagship One (FS1) hasn't been very impressive to me thus far.

 

Yes. With no luck, but for reasons that make me believe it was no good to start with. See above post for explanation.

Also, I have a hard time believing the "good" ECU that I have is bad. It throws no codes, and scans no problem with the OBDII.

 

Shit. I’m sorry I’m an idiot. So, you’d like to try another ecu but from a manual?

 

Yeah maybe. I would need a distributor type 3RZ, manual transmission, manual hubs, non-abs. I don't think the ABS or hubs matter though. It could be from a T100 or a Tacoma. Maybe a 4Runner, but I think the 4Runner wiring and ECU may be different for some reason.

 

Is there a clutch start cancel switch on the 95? Edit: not that it means anything

 

What reprogramming? There is no reprogramming of these computers. Especially 1996. So I would say absolutely they reprogrammed it correctly = do nothing.

 

OP sounds like he knows his shit. Have you tried unplugging and plugging back in? Not really trying to be a smart ass but like let it sit 30 minutes or so with the battery unplugged and then try again. Maybe it’s confused.

 

I think there would be a CSC switch on a '95, but the '85 recipient doesn't have one.

 

I will admit I don't know a lot about ECUs, but it's my understanding that the company flashes the ECU, and checks the logic circuits which is what they mean by "programming" them. Either way, I am nearly certain that an automatic tranny ECU has very different logic circuits than a manual, and I also think they are incompatible. That's probably why I get all of the flashing lights and no connection with the scanner when I hook it up.

 

I have tried it numerous times. At this point, I'm pretty sure I've got no fuel injector impulse AND no spark at the plugs so it's got to be the ECU. It could be bad wiring, but ORS has been making these harnesses for a long time and they are pros. That being said, I'm waiting to hear back from them this week to see if there might be something amiss with the harness.

 

does your harness jumper that so the ECU thinks the clutch is depressed?

 

I'm not sure I know where to look to verify, but I trust the guys at ORS would have thought of that when they built the harness. I'll add that to the list of questions for them this week. Thanks!

 

I *think* that only stops the starter, otherwise you couldn’t bump start the truck, which you definitely can.