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chevy s10

D

Dale2

Member
I have a 2000 model chevy s10 truck I use for service calls and parts pick up. The strange problem I have is I am only getting spark to 2 cylinders. It has 2 coils and I have changed them around and the problem stays with the cylinders so I know the coils are not the problem. I am positive I am not getting spark from the coil. I have replaced the board the coils plug in and that did not help. I know the board has a circuit for each coil, obviously one is working and one is not. Does anyone know what signals come to the board and where they come from? Hopefully someone else has seen this in the past and can offer some help.
thanks
Dale
 
Maybe a mouse chomped a wire off?

Ignition signals would originate from the crankshaft position sensor, be modified for spark timing, then fed to the ignition module under the coils.
 
The crank sensor is able to kill the ignition to only 2 cylinders as the other fire fine? The truck will actually run on 2 cylinders.
 
I have the Haynes book on this trunk and can not find any reference to a crankshaft sensor. Does this engine have one?
 
Forget about the crank position sensor. If it fails, the engine will not run. It cannot possibly affect only 2 cylinders without affecting the other 2.

Among the possibilities:

possible a bad ignition module. Assuming that it has a driver for EACH coil in the coil pack.

Possible bad driver in the PCM.

Here is how it works. The PCM reads the crank position sensor for a reference to cylinder #1. Then, the timing signal is synthesized and the signal is sent to the ignition module. The ignition module amplifies the timing signal and triggers each coil pack when it is time for that cylinder to fire. Some engines also use the cam position sensor to determine if the cylinders are at compression stroke or exhaust stroke. They also use the cam sensor to time the injectors firing.

since you have switches the coil packs, the problem would seem to be either the ignition module or the PCM or a broken or shorted wire between the PCM, the ignition module or the coils.

I repeat, it is NOT POSSIBLE for the crank position sensor to only affect 2 cylinders.
 
I can not find any reference to a crank position sensor for this engine. If it has one can you tell me where it is located. This engine does not have a distributor.I have switched the coils and replaced the ignition module, so am I left to broken wires or the computer?
thanks
Dale
 
Try going into the Autozone website.

You need to register, that give you access to troubleshooting and wiring diagrams sections. No guarantee they will have that model, but it's pretty popular, so good chance they will.

From that you can trace wires back to the ECM, check continuity, signals, etc.

Sometimes unplugging, cleaning, reseating the ECM connectors will fix one.
 
(quoted from post at 18:16:19 03/03/20) I can not find any reference to a crank position sensor for this engine. If it has one can you tell me where it is located. This engine does not have a distributor.I have switched the coils and replaced the ignition module, so am I left to broken wires or the computer?
thanks
Dale
Click to expand...

You didn't tell us what engine you have, but it sounds like you have the "4", which apparently would make it a 2.2.

170934_cavalier_crank_sensor_1.jpg


I would say it's highly unlikely that the CKP sensor could fail in such a way that only one coil would be fired.

Which cylinders are missing, white wire from pin 28 on ECM fires the coil for cylinders 1 and 4, and the orange wire from ECM pin 25 fires the coil for cylinders 2 and 3.



Here's a diagram...

DwBkkmf.jpg
 
Thank you so much. I am an electronic tech so that is what I needed. I will ohm the wires out and hope I find a broken one. Again thank you for sharing your knowledge
Dale
 
If you have no distributor, then you definitely have a crank position sensor. Where it is, I do not know. There are 3 common locations for crank sensors. First is at the front of the engine right behind the harmonic balancer (crankshaft pulley). If it is there, there will be wiring connected to it, and it will be bolted onto the timing cover behind the pulley. Second common spot is at the rear of the engine. Right at the rear of the engine mounted so that it can "see" the teeth on the flex plate or flywheel. Third common location is somewhere on the side of the block.

I would suggest that you invest in some repair literature for the vehicle. Trying to repair modern vehicles with electronics requires that you have some sort of guidance rather then stumbling in the dark by the seat of your pants.
 
The ignition control module controls the coils. The PCM does not have the ability to shut down just one coil. The orange and white wires only control the timing of the spark, not if it happens. If the ignition module does not receive a timing input, it fires the coils at base timing. To check if the coil is being commanded, remove the offending coil, start the engine, and connect a test light across the terminals, it should flash. Have the wires and plugs been changed? On a waste spark GM system, one shorted wire or plug can steal the spark from its companion. Not common, but I have seen it happen. I bet that is what is going on here.
 
Ignore what I said about the computer being able to kill a coil. Just read Identifix and it is possible on this model. I am used to dealing with this system on the V6s, and they work differently. 2.2 was always pretty rock solid runners, so never had the chance to become intimate with the differences. I rarely see any S10s for service anymore, most of them around here the frame is rusted out.
 
Bob I am going to get back on this truck Sat morn. Just want to make sure I understand the pin 25 and 28 orange wire and white wire are on the computer connector on the fender and go to the ignition control board where the coils mount. Is that correct. I have 2 connectors on my computer but will figure out witch one it is.
Thank you
Dale
 
Bob I found the wires you were talking about and they ohmed out good. I could also connect a test light to the contacts the coil plugs into and the coil that is fireing the test light would blink when I turned the engine over. The test would not blink when it was connected to the bad coil terminals. I think all this tells me that the computer is bad. Do you agree?
Thanks
Dale
 
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