Yesterday (Sunday, May 16th) I was driving my 07 Silverado 1500 Classic 2wd 4.3 manual work truck (~130,000 miles) and it lost engine power unexpectedly while doing about 50mph. It gave absolutely no warning, it didn't stumble. It was like the key got turned. Everything else seems to work. All the lights work, I can hear the fuel pump prime when I turn the key, it cranks over, no check engine light, and no security system light. It seems to me to be a spark issue. I tested the coil and it read 6.5k Ohms so that seems good and I have 12+ to the coil when the key is on. It has fairly new cap, plugs, and wires. I have tested all I can without any fancy expensive test equipment and am at a complete loss. The day before it died, I did replace the clutch pedal bracket which requires disconnecting some of the electrical connections near the pedals.

Are there any connections that could come loose that would only effect the ignition system and nothing else? Has anyone had a similar problem and found a fix? I have been doing some research but found everything but an answer to my problem. Maybe the crank position sensor? Distributor rotor (I was going to replace it with the cap and wires but the two screws are very rusty and crumbled when I tried to remove it. Hard life in Michigan for about 10 years.)? I have a new distributor on order to replace the rotor. Any help would be appreciated. Thanks in advance!

 

i think you are on the right track. If it stalled like turning the key off it sounds like a spark issue. loss of fuel pressure would stumble then stall

i would get a spark tester (they are cheap)...connect it to a easy to access spark plug wire and confirm spark when cranking. if no spark....it could be rotor/distributor or a pickup siganl problem. the coil is triggered by the pickup signal opening the circuit.

 

I'll pick up a spark tester and test light on my way home from work today and give an update when I get the time to work on it. Hopefully tonight.

 

I bought a spark tester and confirmed that I have no spark. I tested cylinder 1 and 2 and both of them had nothing when cranking. Is there a way to test the ignition control module with a test light or multimeter?

 

can't find any service info that shows a distributor set up for a 07 4.3...my info s hows 3 coil set up not a one coil distributor set up

this is a general diag for an old distributor system iirc.
test light....to positive side of coil and grd....should light with key on...if not check power feed to coil.
neg side of coil and grd....should flash when cranking....if no flash, the module isn't grding the coil. replace module or check wire to module.

 

I'll be doing some tests on the coil tomorrow. It is the last year of the distributor for the 4.3 I believe. I am not sure if it was just the classic that had the distributor or the new body style also. Thanks for the test procedure. I'll update when I get results.

 

I just ran a few tests and here are the results:

Test light comes on when testing from coil positive input to ground with key on.
Test light comes on and does not pulse when testing coil signal input while cranking. The circuit is not being interrupted to initiate spark.

I cannot find anything wrong with the wiring. I will be ordering an ignition module and crank position sensor. Are there any under dash connections that just control ignition?

 

not familiar with you build so i can't give specifics. not sure what purpose a crank sensor is needed for with a distributor setup? is the ignition module in the distributor....the ones i have seen have the reluctor and pick up in the disbributor....so no crank signal is required. if the crank signal in yours is used to signal the coil....you should check for rpm signal with a scan tool when cranking. should be aro und 250rpm

 

Here is a picture of the coil and ignition control module. It is not part of the distributor. Its located on the passenger side of the throttle body under the intake tube. In my research, I have found that the ICM gets its signal from the crank position sensor. I will test the crank position sensor this weekend.

 

I tried to dive deeper in troubleshooting over the weekend and am almost completely convinced that the problem is an electrical connection (or ground?) under the dash. There is no spark signal at any component in the ignition system. I have 12+ to the coil, ICM, and crank position sensor but no pulsing signal. Are there any resources to find complete wiring diagrams for these trucks? I want to go through all the connections in the ignition system and do continuity tests.