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Thread: New Vacuum Pump - now no cruise control?

  1. #1
    Join Date
    Feb 2017
    Location
    Jonesboro, GA, USA
    Posts
    9

    Default New Vacuum Pump - now no cruise control?

    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

  2. #2
    Join Date
    Apr 2001
    Location
    CA
    Posts
    13,573

    Default

    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.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  3. #3
    Join Date
    Feb 2017
    Location
    Jonesboro, GA, USA
    Posts
    9

    Default

    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

  4. #4
    Join Date
    Jan 2001
    Location
    New Hampshire - Live Free or Die
    Posts
    6,057

    Default

    It's all part of the electronic throttle in the PCM. Did you check for codes, or just clear them? What were they?
    The Constitution needs to be re-read, not re-written!

    If you can't handle Dr. Seuss, how will you handle real life?

    Current oil burners: MB GLK250 BlueTEC, John Deere X758
    New ride: MB GLS450 - most stately
    Gone but not forgotten: '87 F350 7.3, '93 C2500 6.5, '95 K2500 6.5, '06 K2500HD 6.6, '90 MB 350SDL, Kubota 7510

  5. #5
    Join Date
    Apr 2001
    Location
    CA
    Posts
    13,573

    Default

    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.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  6. #6
    Join Date
    Dec 2000
    Location
    Walla Walla WA
    Posts
    69

    Default some things to look for

    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.
    1994 K2500 ext cab. Recently repowered with; Non-cracked 599 block, factory compression, used old DSG girdle for main caps. Factory for what remains. Changed diffs to 3.42. Fuel economy Hwy 22.5 mpg US, in town without lcokup in 2nd/3rd - 18 mpg US.
    1994 K3500 CC LB Silverado. Next project. Built for endurance, power and gearing. Plan on opened up intake and exhaust sytem, best cooling mods, 4.11 gearing 4L80E, followed by Gear Vendors OD. Need to be able to split all gears and have lockup in 2nd/3rd/4th. Tan interior cloth, Bad ass dark blue (coming) aluminum wheels and air ride (coming)

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