New Vacuum Pump - now no cruise control?

[drgerry]

I recently had a new vacuum pump installed. Now my Cruise Control won't work. It won't even come on (no "cruise" light on dash). Fuse is good, no ABS codes. Brake light switch works.

Any Ideas????

PS: 1996 GMC Sierra 1500 6.5L

[DmaxMaverick]

CC on your truck is 100% electronic controlled (outside your manual input from the control switches). Check for DTC's. Many error codes will disable CC. Also consider any other things you may have messed with. If the stalk/control set is disconnected (by whatever means), CC won't be available.

[drgerry]

Thanks for the reply.

Haven't messed with anything, it runs too good. The only reason I replaced the vacuum pump was because I heard a squeaking noise coming from it. I have cleared all DTC codes, still no cruise.

I'll have to locate my schematic to find out where the CC control module be

[JohnC]

It's all part of the electronic throttle in the PCM. Did you check for codes, or just clear them? What were they?

[DmaxMaverick]

Yes, 100% integrated in the PCM. The PCM is the "CC module". It's behind the glove box.

If the STS lamp (Service Throttle Soon) isn't on, then the PCM in inhibiting CC for some reason, or communication with the stalk is broken, somewhere. The stalk is relatively cheap and common for a reason (less than $30 at last check at the "HELP" rack) and not too difficult to replace. It's likely you'll spend more money and effort chasing the problem if there are no codes and the SES/STS lamps aren't on. Try clearing codes, even if you don't see any. Disconnect BOTH Batt+ cables from the batteries and ground one to chassis for an hour and try again. If it still doesn't work, replace the stalk. To echo another post yesterday, normally I'm opposed to just throwing parts at a problem, with very few exceptions. This is one of them.

[jggiedeman]

Hello,
you didn't mention if 2WD or 4WD. Sometimes the connectors on the front axle actuator can come loose, break, or others. Just takes a few seconds for a dropped tool to bang one of them. My FIL had an issue with his windshield wiper motor that knocked out his cruise.
Brake pedal switch out of position. There are a few tranny faults but you mentioned no codes.