That means you are getting a crank signal. I doubt you have a PCM problem. They are pretty bomb proof. I'm sorry I can't offer more at the moment, I'm running out the door. Did you check the ground wire at your Ignition Control Module with your voltmeter? It grounds on the back side of the left cylinder head (after it has gone through splice S152). Real PIA to get to but maybe with mirror you can see if the ground wire is broken off. Sorry I can't give you pin outs at the moment to just check with voltmeter but I am running out the door.

 

Either post can spark. But check your block ground real well anyway as well as the ground straps at the back of the engine. Bad grounds can cause crazy stuff.

 

This may help:

Part 1 -How to Test the Crank Sensor (GM 4.3L, 5.0L, 5.7L)

George

 

I was rerunning all my tests after discovering that the crank sensor is giving a signal. When I did the led light test on the switching signal wire on the icm, wire B, the white wire, it didn't light up at all. The test says to see if it flashes. It didn't flash but it didn't light like it did when I tested the same in the coil test for signal. The test says it doesn't matter matter if it light stays on but no mention of not lighting. How can something flasf if it can't light? This situation is really stumping me. If I can't fix it then I have to take it to a shop. Up here that means at least 500 and I live on a disability pension. I've managed to get broken zr2s cheap and fix them up myself but electrical of this type is my first and my weakness because I'm from the no computer era. Any ideas on not getting any light on that test?

 

So your getting a switching signal into the coil but not into the ICM?

Please describe your switching signal test?

George

 

I put a probe into wire B, the white wire (2nd beside pink). I put the light on the probe and the other end on the positive terminal of the battery. If it flashes it says it's a problem but okay if the light stays on when you turn the key or crank it. In my case no light at either. But the same light flashing test on the other wire previously left the light on.

 

A shorted Camshaft Position Sensor or circuit can pull other sensors down. It can even shut the VCM down. I know it's a PIA to get to behind the distributor, but you might want to unplug it to see if that changes your no flash results. Of course that only checks to see if the CMP itself is shorted.

 

I have gone over all the tests again only now my tach is not moving during cranking. I thought it moved last time but maybe just current in the system. Now nothing. It doesn't move. You mentioned something about it. It's a national holiday in Canada today so everything is closed but I think if I don't get it going I'll have to get it to a shop with a scope. That's scary because there is so much corruption in the repair shops. Do you think the lack of tach movement suggests crank sensor?

 

Sounds like you are not getting a crank signal. Probably same reason you're not getting any flashing now. Try unplugging the CMP and cranking with everything else plugged in. Another note though, if your battery voltage is to low from all the tests, it may need to be charged.

 

Unfortunately there are limitations to not having a scope. For instance, though you were getting a crank signal it could have been erratic and you really don't know. I got into scope work a few years ago after being frustrated that the voltmeter only got me so far. If you are doing all your own work, a decent two channel scope or DSO would be a good investment. It doesn't have to be a Snap-on or Hantek or Pico. You can find decent two channel DSOs for a couple hundred bbucks. Makes your money back in the first few parts you don't needlessly replace. Of course there is the whole learning part, but there are plenty of videos online and great pubs.