No Spark - 4.3L S10 Pickup
The engine stopped while I was driving down the highway at 60mph. I could not get it to restart. Had a tow-truck take us home.
Using the Hayne's Manual Diagnostic Flow Chart,
I tested for: spark at the plugs - No Spark
spark at the coil wire - No Spark
test the Coil - results all positive (the coil is new)
Check voltage at terminals A & D of the Ignition Control Module -
>10v at A, <10v at D (This is the problem) The ICM is new also. I have also replaced the Coil Wire, Cap & Rotor. The Crankshaft Postion Sensor tests fine. (Alternating 5v pulses) There is also >10v going to the coil at its terminal A.
The grounds are good at the coil and ICM.
There is good continuity at the white wire w/black stripe between coil and ICM.
These results led me to believe the PCM was at fault, so I replaced it too.
It still will not start.
The first time I tested ICM terminal D, it gave a reading of >10v.
Since the replacement of the PCM, it shows <1v at terminal D. This is still a No Spark condition. Last summer I replaced the fuel pump & filter, the spider fuel injection assembly, and the heads. All with new gaskets. It has been running like new, until this. I have not replaced the Ignition pickup coil (camshaft position sensor). Could this be the cause of the low voltage reading at terminal D?
Ignition switch? Wiring at the starter? That's where I'd look next. HTH. -Jim
sounds liker high resistance ,poor ground or frayed wire somewhere
Thank you Jim and Jimmy. I think I've found the solution. It seems to be in the connector to the Ignition Control Module. The White wire w/black stripe from terminal D on the ICM to terminal C on the Coil shows enough continuity to light an led test light, but a test with a multi-meter shows a significant drop in voltage. I'm going to see if I can temporarily bypass it. If that works, I will get a new connector. Jim, one of the tests for the ignition switch is the same as for checking voltage at terminal A. I have >10v there. I'll let you know how it goes.
You're welcome. Glad to help. Yes, please do. -Jim
On the road again. It was a bad connector that caused me grief. I replaced the connector to the ICM, but still had a no-spark condition. So I started re-testing, which took me back to the coil. The coil tested fine, the problem still seemed to be with the coil driver wire (white w/black stripe). I pulled everything out of the conduit and could not find any visual signs of damage. I got (false) positive readings for continuity. There was just enough contact for that reading, however I still had significant voltage drop. I replaced the coil primary circuit connector, and I am a happy man again.
Awesome! Thanks for letting us know. Very glad you're back on the road! -Jim
Question? How did you bypass the ICM? Is there anyway to bypass all these sensors?? Im beating my head against a wall with the dumn things.
Hi Brandie, I didn't bypass the ICM. I bypassed the connector by connecting the wires directly to the ICM terminals. That was how I knew it was the connector itself. I wired a new connector in, and it's been running fine for the past year and a half. I don't think you can bypass the sensors, as they all play a part in the proper functioning of the engine. I used the diagnostic flow-chart in the Haynes manual to systematically test each component, and continuity of each wire. It took a lot of time. Good luck.
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