Cruise control

[Zooker]

Cruise control not working. Got a module that mounts to firewall and connects to tpi/carb and changed it guy said that would fix it? No luck. Any suggestions?
91 gmc 5.7
Any test or known issues I could check into.

 

[RDF1]

So there's several things that could cause this.
First thing is check for power and ground. Then check brake switch.

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[PlayingWithTBI]

I don't think the 88 - 91 years had a connection to the ECM. Here's a link to service manuals (thanks to @hatzie ) go to the 91 wiring manual and to page 118. There you'll find some troubleshooting hints.

https://www.gmt400.com/threads/88-95-service-manuals.43575/

 

[bugdewde]

Do your brake lights work ? That's the only test I know of.

Also, brake lights go through the hazard light switch.... I know i had issues with my hazard light switch and my brake lights, trailer brakes (& maybe cruise ) wouldn't work. Jiggling the hazard switch button would get brake lights working again.
Eventually had to "shim" the switch button against the column housing with 2 pennies to make contact.

 

[RDF1]

I thought the original post said 97'. I see it says 91' now.... disregard my post..

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