Hi I have a 92 3.0 Toyota 4Runner. Problem is it was becoming harder and harder until one day it started no more. It cranks, I get spark, fuel pressure is great, tested the ignition module and it showed good, fuses are good, relay clicks. With a meter I checked the wire harness at the injectors and get 12v on the power lead and the ground control lead. Checked the ground control wires (Toyota has two) at the ECU and have 12 v on those and I shouldn’t, also no pulse with a noid light. Thought it was the ECU and replaced it. What’s interesting is if you unplug all six injectors then the system is good meaning no power on the ground control wires at the ECU or injectors and the noid light pulses but plug in even one injector and nothing works. I did check injectors and get 12 ohms on all injectors. Of note I do get a check engine code ignition system. Thought it could be a worn though wire but don’t see that as possible being the system works when not plugged into any injectors. People say it’s the crank position sensor but I don’t believe this has one. I’m at a loss here and any ideas would be helpful, thanks.
More often that is a computer failure because if you hook up any injector and it goes dead that means the computer doesn't have enough power to even run one injector so I would suspect computer driver failure
@scottykilmer
I changed the computer with a known working computer, could it be a power issue to the ECD?
Bad wire or connector in injector harness. It can handle the load of the noid light but not 12ohm injector. Never say never when it comes to wiring and connectors.
@heyinway
My connectors do look worn some wire casings are split at the injectors, when plugged in though they shouldn’t read 12v on the ground control though, something is causing power full tile to the ground control circuit
I think those computers as with most circuits in the Japanese cars are ground seekers.
I would give a good hard look to the grounds provided to the computer and the different points on the wiring harness. This smells of ground issues on an older car and I am willing to bet a dollar (I give you a hug to get the dollar LOL) that there is nothing or little wrong with the wiring or the computer... this is a ground issue and should be traced down with a volt meter and common sense.
NOTE** Everything is reverse thinking with a ground seeking circuit. Power is provided to the devices and they seek ground through a switch or through the FET transistors mounted inside on the walls of the computer or ECU module. Its easier to switch ground than to provide power to everything in the car. Makes fusing simpler also. 😀 Be methodical and logical as you check this.
The meter will also tell you about ground problems. Check between the neg terminal of the battery and the head, the injector bodies themselves, the computer metal case, the steel bars in the dash, the alternator case, the body of the car.
Like Ross Perot used to say, "The Devil's in the details Larry"
