I'm working with a 5.3 swapped '93 Blazer, and I can't seem to get the cruise control to work. It's a Gen III engine with a 0411 pcm.
I installed a used cruise control module off an early '00s Silverado, and it plugged right in; supposedly the wiring is all the same, except for the Cruise Signal wire.
I routed that from the factory Blazer harness connector to the 0411 PCM connector, but it does not work.
The new cruise module has power, ground, brake switch input, and all signals from the cruise switch are correct.

I hooked up a scanner today, and control is never shown to be active.



Question: does cruise control have to be enabled in the tune, or are all Gen III PCMs cruise-ready? I don't remember if the donor truck had cruise or not.

Could this just be a bad module? Is there any way to bench test it?

 

Swaps can have all sorts of non standard problems, but I would first check to see that there is not some code that is turned off that automatically kills cruise control. Swap vehicles usually have all kinds of random code deletes. If that is not it, my next stop would be reading wiring diagrams for the donor vehicles of all components involved.

 

That cruise control module will work with a carburetor with a VSS signal provided to it. It is not tune related as it is an external module that is not PCM controlled at all. The cruise signal is an input to the PCM for the cruise control shift points. If the brake switches and cruise control switches are providing the correct signals to the correct pins you have a dead cruise module.

 

Can you log the positions of the cruise control switches? Just to confirm that the PCM is reading all of them correctly.

 

He is using the older DBC cruise control. It does not have direct communication with the PCM.