95 chevy s10 4.3 TBI 293k miles. I’ve been getting a CEL at startup for a while, it was just for a minute when I started the truck, then would go off. PO320 code and sometimes a PO328 code also. My scanner calls both the codes electronic spark control circuit fault and ESC open circuit. Looking up the codes online, they relate to knock sensor and crankshaft position sensor. The truck doesn’t have a crankshaft sensor that I’m aware of.
I swapped the cap, rotor, ICM and ignition coil with no difference. I spliced new connectors for the ICM and now the PO320 stays on all the time and it runs rough. I didn’t mix up any wires. I’ve also had a malfunctioning temp. gauge which started around the same time. I suspect it’s a wiring problem, but don’t know. The truck has 2 knock sensors, one has been replaced a while back and the other is under the distributor at the rear of the engine and is very hard to access. I’m not good with the electrical diagnostics, I’m hoping someone could steer me in the right direction. Thanks
Your truck’s timing probably works similar to my car, the ignition timing is determined by the distributor shaft’s angle of rotation. At that mileage, it could be anything, including the timing chain of course. But if I had that problem before assuming it is thetiming chain I’d try replacing the timing sensing parts inside the distributor first. If that didn’t do the trick, I’d probably next replace the entire distributor. If the distibutor it original to the truck, at that mileage I’d probably just replace it rather than bothering with the timing parts. Presuming the new distributor comes with new timing parts.
It may be possible to assess the timing chain saturation by measuring the amount of play between the crankshaft and the camshaft.
Keep in mind that your replacement ICM may be faulty.
It became evident that modules and crank sensors failed somewhat simultaneously so replacing them together was worthwhile. For the DIYer replacing the distributor is necessary.
