all accessories work and it turns over but no spark to the wires?

Hello thespindoctor

I am sorry you are having troubles with your vehicle. The ignition control module is probably faulty. This would cause no fire at the plugs and also possible reason for blown fuse.

Hope this helped.

Hi, is the security light flashing when the key is on?

There are no lights flashing when we turn on the ignition. The service engine light was on before these problems occurred due to a bad catalytic converter.

According to the mitchell online manual I have purchased, there is no ignition control module on these vehicles with a 5.3 L engine. There is mention of one on a 4.8 L engine. Is the ignition control module part of the PCM?

No, it is not part of the PCM.

The 5.3L ICM is made into the ignition coil pack. You must replace whole coil to replace ICM. This is also true for the 4.8L and 6.0L engines for your make and model vehicle.

I believe there is a problem with the PCM because the scan code computer cannot make a connection with it. Is there one ignition control module for the engine or a separate one for each cylinder?

Hi, have you checked the crank angle sensor? If it fails, no spark, GM had a problem with that sensor.

I know that the crank position sensor will cause the lack of spark, but I reason that the scan computer should be able to communicate with the PCM and mine can not. It does communicate well with my other Chevy, so I don't think the scan computer has failed.

But you also mentioned that it says to turn ingnition on and then when you do it says no connection. Can not sense ignition being on if the ICM is faulty..
or if faulty relay is preventing coil packs to perform.

I tried to get an ICM from the parts place nearby and we cannot come up with one for the Silverado 2000 5.3L engine. Should this be one part or is there a coil for every cylinder? I have replaced the ignition relay and all fuses are good.

Thanks

The 5.3L ICM is made into the ignition coil pack. You must replace whole coil to replace ICM as stated in earlier post...

So there is a coil on each cyclinder, I would have to replace 8 coils correct?

Thanks

Each one has the ICM, yes. If you firmly believe that the PCM is faulty then replace it and post your results.

I will give the new PCM a try and post the results. If the PCM replacement does not do it, it will be time to tow the car and give up on the do-it-yourself effort!

Thanks

Hi, can you run a test for me please?. Remove one of the injector wires, with the key on, probe both wires, one should have 12 volts. Please let me know. We are testing the system for operating voltage.

Hi. How did that new PCM work out? Having exact same problem.

Hello,

This is an old post but we can pick it back up again. Can your truck communicate with the scanner? Here is a video to help you read the codes:

https://youtu.be/v0ayZE5kq1Y

If it does not connect lets test the fuse #7 which powers the ALDL connector. Here is a guide and diagrams to help you get started:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Check out the diagrams (below). Please let us know what happens.

Cheers, Ken

The truck is unable to communicate with the scanner. Is powers up from the port but says unable to connect. All fuses have been checked and are good.
The security light comes on solid after sixty seconds with key on. It never goes off.
The truck cranks and starts for a quick second but will not stay running.
I replaced the passlock key housing, the key cylinder with new key and the ignition wiring harness but no luck.
I am debating whether to have it towed to dealer or try buying a new PCM. I have had four tech guys try to figure it out but no luck. I did the relearn of the new key. Key in start position, wait ten minutes, light stops blinking and repeat three times. It seems to have learned the key because light stops blinking, but the light comes back solid after sixty seconds like it is a different problem.
Any help would be appreciated and thanks Ken for the response!
2000 Chevrolet Express 3500 diesel
18,000 miles.

18,000 miles :) I love it. my favorite truck but it does sounds like the PCM is out or we have a wiring issue. Let's check the power and grounds to the PCM to confirm its failure.

Check the power and grounds. Here is a guide to help you get started and the location of the PCM:

https://www.2carpros.com/articles/how-to-check-wiring

Check out the diagrams (below). Please let us know what happens.

Cheers, Ken

Thanks Ken for the great information! I am going to test this and get back ASAP!

Please do.

So, I tested all the grounds and power to the PCM. Everything tested as it should based on the schematics you provided. I did all the testing with the key in on position. As I was testing, the security light went off and the OBD scanner could now suddenly communicate and the van started! I have no idea what the problem was but as of now, it works! Maybe leaving the key on for over an hour reset the security light? Maybe there is a wire loose somewhere? Thanks Ken for the help!

It could be the PCM is going out or you have a bad connection. I would remove the electrical connects at the PCM to check for corrosion just to be safe. Below is the PCM location. Check out the diagrams (below). Please let us know what you find.

Cheers, Ken