No spark from coil

[driver540]

97 Chevy c1500 4.3L Manual Trans. Have replaced distributor,cap, rotor,wires,cam sensor,crank sensor,new timing chain and gears and new coil and ignition control module. Have no spark coming out of coil. I checked for voltage going to coil. Shows 12 volts, but no spark. Any ideas what to do next?

[crank.it]

hey driver-try and check your motor and chasis grounds then recheck the timing....crank.it

[driver540]

I had spark and the truck ran, but i installed the new distributor when it quit running and found i have no spark now. It comes and goes it seems. Was leaning towards the ignition switch, but i hope not after all the money already put into the darn thing. [smilie=pdt_vis.gif]

[jgate]

If the connections and the harness check OK, monitor a digital voltmeter connected between VCM terminal C3 pin 9 and C4 pin 18 while moving related connectors and wiring harness. If the failure is induced, the voltage reading will change. This may help to isolate the location of the malfunction.
An intermittent may be caused by any of the following conditions:A poor connection, Rubbed through
wire insulation A broken wire inside the insulation
Check your grounds from the ICM and the CMP sensor ground.
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[driver540]

Ok. Have checked continuity and checked all grounds and all seems to be ok. Got no voltage change in voltage between C3 pin 9 and C4 pin 18. Got 1 volt with key on and a negative 3 volts with key off. I am going bald quick with this truck. LOL. Any new ideas?

[fstf2v]

driver try and check the clutch safe start switch- hope this helps

[jgate]

Can you pull DTC from the PCM? like a P1361,P1351,or P0339>
With all the new parts you installed, you seem to replace every thing in that circuit.
Except the VCM.And I know you don't want to go there until all options are exhausted.
My thoughts are you either have a short in one of the harnesses, that will not send a timing, or tac signal to the coil. The coil driver is in the ICM. And the ignition timing signal is in the ICM, that is controlled by the VCM,That is supplied from the CRK sensor.You have checked all the power leads and ground leads to the CRK, CMP, and the ICM right?
Even with just trying to start this vehicle a DTC should set.
Check for codes in the PCM. and let us know what you come up with.

Here are a few tests that you could do to start eliminating possible causes..

With the ignition Off. Disconnect the ignition control module harness connector.
Probe the ignition control module harness connector terminal B with a DMM set to the AC scale.
Crank the engine. Is the voltage reading within the 1-4 Volt?

Turn OFF the ignition.
Disconnect the VCM C3 connector.
Probe the VCM C3 connector pin 9 with a test lamp connected to B+.
Is the test lamp ON?
(REMEMBER ALWAYS USE A LED TEST LIGHT)

With the the ignition off.
Probe the ignition control module harness connector terminal C with a test lamp connected to B+.

[driver540]

PO336 CKP out of range is what I get. Checked with my "brick" and get no RPM signal while cranking engine either.

With the ignition Off. Disconnect the ignition control module harness connector.
Probe the ignition control module harness connector terminal B with a DMM set to the AC scale.
Crank the engine. Is the voltage reading within the 1-4 Volt?

I did this and got 0.1 volts while cranking engine on the AC scale

[jgate]

DTC PO336 refers to CKP sensor performance.
with the ignition off.
Disconnect the VCM C3 connector.
Probe the VCM C3 connector pin 9 with a test lamp connected to B+.
Is the test lamp ON?

Disconnect the crankshaft position (CKP) sensor.
Turn ON the ignition leaving the engine OFF.
Probe the CKP sensor harness connector ignition positive voltage circuit with a test lamp connected to a ground.
Is the test lamp ON?

Connect a test lamp between the CKP sensor harness connector ignition positive voltage and sensor ground circuit.
Is the test lamp ON?

Install a DMM set to the duty cycle position (select AC voltage and press Hz button twice to display duty cycle) between the CKP sensor signal circuit and the CKP sensor ground circuit. Crank the engine.
What Is the duty cycle?

[driver540]

Disconnect the VCM C3 connector.
Probe the VCM C3 connector pin 9 with a test lamp connected to B+.
Is the test lamp ON? YES

Disconnect the crankshaft position (CKP) sensor.
Turn ON the ignition leaving the engine OFF.
Probe the CKP sensor harness connector ignition positive voltage circuit with a test lamp connected to a ground.
Is the test lamp ON? YES

Connect a test lamp between the CKP sensor harness connector ignition positive voltage and sensor ground circuit.
Is the test lamp ON? YES

Need to get a different meter to that has Hz on it to measure the duty cycle. Will get back with that info ASAP

[jgate]

Disconnect the VCM C3 connector.
Probe the VCM C3 connector pin 9 with a test lamp connected to B+.
Is the test lamp ON? YES


The test light should NOT come on in this situation.
repair the short to ground in the ICM control circuit.
You do have the proper schematics for this right?

[driver540]

No. I dont think so. If you have it, it would be greatly appreciated if you could post or send them to me.

[driver540]

jgate Wrote:Disconnect the VCM C3 connector.
Probe the VCM C3 connector pin 9 with a test lamp connected to B+.
Is the test lamp ON? YES


The test light should NOT come on in this situation.
repair the short to ground in the ICM control circuit.
You do have the proper schematics for this right?

I have re- ran a new ICM wire and test light is out now but, still no start. I used test light to pin 9 with it plugged in and light is back on again. Does this mean I have a bad VCM?

[jgate]

I really hate to say this but it kinda is headed in that direction..The ICM control driver is in the VCM,And the driver could be sending this circuit to ground,. you replace every component in that circuit, and taken care of the ICM short, and tested the power and ground leads to all the components, the only thing left is the VCM, unless the short is in the ICM itself.. or there is a problem with the reluctor ring for the CRK , how did it look when you had it out when you changes the timing chain? and of course you did check the ENG1 fuse right? the ECM fuse supplies should be good since it is the pink wire, and you did state that you have battery voltage to the coil. You mentioned an ignition switch in one of your earlier posts, I can't see that being the problem , because you have power to all the components in that circuit. The problem is A new VCM is really costly for that 97 and you will have to have a "flash" after installation.
I will send you some more emails, just double check all the connections, look for missing or bent pins,and check all the power leads and ground leads,and check the ICM for an internal short .

[driver540]

I think my icm may be shorted. I checked continuity between terminals and 3 of the 4 show they have continuity.