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I have been trying to figure out this problem for a while. I wrote a post a little over a year ago that explains my issue. I gave up on it but now I have decided to have at it again. I have a misfire on the #3 on my 1995 monte carlo ls with the 3.1 v6. When I checked the fuel injector it checked out ok. Checking the wires with a test light and the engine off it shows that the two wires are grounded. When I start the car I have nothing on either wire going to the injector. I then back probed the #3 injector out wire at the computer and restarted the car to see if the computer was sending a signal to the injector. it showed that that wire is grounded. Is the driver circuit bad and I need to look into another ecm? What else might cause that issue?
Hi Paul. Thanks for the diagram. I took another fuel injector wiring harness an with great care tied it into t5he fuel injector harness on the car. I then took a LED test light and attached the lead to the positive side of the battery and took a wire and came off of the pink and black wire and attached it to the test light It li up green. I then started the car the light pulsed until the car started and then it went out. when I pressed down on the accelerator in drive it pules once and the goes out. When I continue to press down on the accelerator it will pulse thru 2nd and 3rd gear . When I let off the gas the light stops pulsing and does not pulse in overdrive and starts missing even worse. I also noticed that when I use my signal lights it will pulse in sink with the signal light. I have no check engine light to give me any codes. Is there a bad ground somewhere. Where should I start looking?
Unplug the injector and put your incandesent test light in series with the conector, Sart the engine, what is the test light doing?
To check for a path to ground other than the PCM. Unplug the PCM, Ignition OFF, and use an incandescent test light attached to Battery Positive and gently touch Injector 3 control wire at the PCM Harness.
The best way to see the operation of the injector is with a current clamp and a pico scope, but if these are not available then you can disconnect the injector harness connector, and measure the injector resistance with a DMM. If you don't have a DMM just get a new injector and swap it out. A failing GM injector can be very strange depending on how it is failing internally. Some go open, some partially short which caused the ECM to current limit and shut down, and sometimes they only do this strange behavior when hot.
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