Edmunds Answers

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  • avatar karjunkie 08/28/09 12:00 pm PST

    I think you are on the right track. Intermittant failure and setting its own speed at times would lead me to believe the problem is in the vehicle speed sensor that is part of the cruise control circuit and goes through the PCM. First I would detach and clean the connection to the VSS with electrical contact spray. If all else fails, I would change it.One last thing to check is the brake light switch. A bad one can cause gremlins with the cruise control. Let me know what you find!

Answers

  • karjunkie 08/28/09 12:00 pm PST

    I think you are on the right track. Intermittant failure and setting its own speed at times would lead me to believe the problem is in the vehicle speed sensor that is part of the cruise control circuit and goes through the PCM. First I would detach and clean the connection to the VSS with electrical contact spray. If all else fails, I would change it.One last thing to check is the brake light switch. A bad one can cause gremlins with the cruise control. Let me know what you find!

  • flyboy2001 09/08/09 5:53 pm PST

    Many thanks from karjunkie, it took some time since I had to order the stop light swt. ,but relaceing it was a 5 star fix From Flyboy2001

  • karjunkie 09/09/09 7:45 am PST

    Congratulations! Glad to hear it was just the brake light switch. A lot of people forget it is part of the circuit for the cruise control. Enjoy your ride!

  • flyboy2001 09/11/09 9:30 am PST

    From Flyboy2001 .I guess I spoke too soon, the cruise will not enguage again only 3 days after replacing the stoplight swt. Speed sensor has been replaced,cruise control module replaced, but still no cruise.Only items I can see left are multifuntion swtich(cruise lights wipers) and PCM.???Any Ideas out there??

  • hotnhorney 07/04/11 4:25 pm PST

    Hope this helps someone. I had the same issues on my car. After replacing the cruise control module, and brake light switch, I still had the same issues -- then I pulled the shop service manual and read. Here is a fix that worked on mine. There are two switches on the brake pedal. The lower one is stop light and cruise control inhibit. The top one is Throttle cable control and the Cruise release switch. This top switch must be adjusted with a 1/16 clearance between the barrell (Not the plunger) and the mounting bracket!!! Too little will result in gremlines and too much will result in gremlins!! I messed up the adjustment a little when I replaced my Cabin filtlers, then I just put tht switch in until it bottomed and twisted to tighten, leaving no clearance. That is when my problems began. If your speedo works your speed sensor must be okay. This adjustment caused my car to refuse to set cruise, and to accelerate to any speed it wanted to. So, This adjustment is VERY VERY IMPORTANT. Out of adjustement and the switch aparantly sends mutiple signals to the ECM (MY guesson this comment)

    Source: PAGE 8-693 GM SHOP MANUAL

  • hangingin 04/01/12 9:33 am PST

    I want to help. After two years and a couple of hundred dollars I fixed mine. It is 2001 park avenue with exactly same symptoms. I noticed that when the car was cold (Interior too) the cruise worked but when it warmed up it was anyones guess as to what it would do. I first replaced the control module - no fix. Next the brake and cruise control switches on brake pedal - no fix. Cables on throttle body were free and moved freely. I looked for an air leak around throttle body and found none. Cruise was slow to latch onto the "set" speed. I replaced the VSS vehicle speed sensor - no help. ONLY ONE THING left. and I did not want to replace the Multi function switch in the steering column. That was over six hundred dollars and a bear to get into. Finally with nothing else left to fix I went this route. To cut costs I got a used steering column from a salvage yard for ninety dollars with the switch intact. Only two screws to take out, but getting to them was a bit difficult as one was hidden above the ignition switch. The switch had to come out first. Do not try to remove the steering wheel cover without taking out the switch first or it will crack. There is one tork screw above that lock switch. Use a 4mm socket and 1/4 drive extension and you can get it out without cracking the column cover.
    Work in this order. Remove the fuses and battery cable. Remove the air bag from the steering wheel. Special tools make this easier to pull the springs back and release the air bag. disconect the wires. Remove the air bag. Remove the torq screws and the lower S.C. cover. Remove the upper S.C. cover as outlined above. remove the Steering Wheel balancer (3 screws). Now use a special tool to remove Buick steering wheel (DO NOT HAMMER ON THE COLUMN in any way.) Remove the lower instr. panel on left side (two screws). Remove two screws that attach the multi lever assembly. Now pull aside but do not take completely out. Locate the cable that match the ones on the " new" Unit. Thred the new cable along side the old ones and ONE AT A TIME Switch the plugs, removing the old and plugging in the new ones. Bolt down the new unit to steering wheel. Put it back together in reverse. DO NOT RECONNECT BATTERY UNTIL ALL IS 100% REINSTALLED.
    This fixed my problem! I did an autopsy on my old unit. There were two small contacts inside that were burned rather badly and kept the 2 amp circuits from doing their job. It took me about four hours to do the job. Having a complete old steering column and the experience taking it apart made the job do-able. You will need a special steering wheel puller with slim legs and special tool (or you can make one out of heavy solid wire like an old antennae to pull the springs back to relase the air bag). When nothing else cures the problem then try this fix. These multi function units DO GO BAD. Mine had about 75k miles on it and several trips across country on it to california from Ohio. Again I recommend getting a complete steering column for about $90.00 and taking your part out. It enables you to see the things inside and get the experience of taking it apart. Also see you tube for how one person did this on a slightly different steering column. Good Luck (You will save about six hundred by doing it yourself). Hope this helps you. And yes this was causing the unintended speed up of car without warning, made the unit slow to engauge, refused to engauge, kick off, etc. Post back and let me know if this post is of use to you. I will monitor and repost if you have questions. perhaps I will add postings of caveats if not just work slowly, follow the wires, have the correct tools and good luck.

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