Cruise control quit working

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GNRick

Retired member
Joined
Mar 21, 2004
Messages
5,485
First I installed a new stalk. No luck. Then I swapped the hole vacuum/electric gizmo under the hood on the driver's side fender with a known good one. Still no luck. So I'm thinking maybe it is the black box located under the dash? Or could it be an electrical issue? The cruise light comes on, on the dash. When I pulled the vacuum lines off I could hear air escaping, and the car had been sitting for 3 days, so I don't think it is a vacuum leak. Thanks.
 
Rick

Make sure the switch on the brake pedal (one with vacuum line) is being fully compressed when the brake is parked.

RL
 
Funny you should suggest that. My daughter's cruise control on her VW Jetta had quit working and it was the brake switch. I was wondering if it could be electrical in my brake switch but you are saying there is a vacuum line connected to it? Are there two switches on the brake pedal? So with the brake pedal up it should be compressing the switch.....I'll check it!
 
Tagging along...

Mine tried to kill me. I turned the cruise on at 60 MPH on the highway and engaged ludicrous speed! Pedal went to the floor and I had to turn it off at the switch on the stalk. I went thru the whole troubleshooting flow chart and found nothing. It's either the module under the dash or something in the VSS circuitry.
 
Funny you should suggest that. My daughter's cruise control on her VW Jetta had quit working and it was the brake switch. I was wondering if it could be electrical in my brake switch but you are saying there is a vacuum line connected to it? Are there two switches on the brake pedal? So with the brake pedal up it should be compressing the switch.....I'll check it!


Yes there are 2. The one with the vacuum line is for cruise. Yes brake pedal up, switch compressed.
 
I found the same brake switch out of adjustment which caused my tcc not to lock, also fixed my cruise control at the same time! Is your tcc lockup working properly... if you have a lockup converter?
 
I found the same brake switch out of adjustment which caused my tcc not to lock, also fixed my cruise control at the same time! Is your tcc lockup working properly... if you have a lockup converter?
Not sure....rpm's are about 2200 at 70 mph. How do you check the lock up?
 
Get up over 50 in 3rd or 4th gear. Constant cruising speed, keep your foot steady on the gas, then tap the brake pedal with your left foot. The TCC should unlock and you'll hear the engine rev up a few hundred rpm's and then back down as the TCC locks again.
 
Ok, I pushed the upper switch in the mount so the brake pedal will depress the "plunger" more when the brake pedal is in the up position. Does it sound like I'm on the right track?
 
Yes I believe that when the brake pedal is at rest the plunger should be fully depressed. How far out was it?
 
Maybe like 1/4" . Now it is like 1/16". Had an interesting experience today. Took my other TR to local shop for oil change. I supplied the VR1 racing synthetic. Anyway I pick it up and shop owner says the upper rear control arm bushings fell out (passenger side). He says I need to get them installed and get it aligned. So I reminded him that about 2,000 miles ago his mechanic replaced the upper control arm bushings so it is his fault. Finally he tells me ok get it done and bring him the bill. I told him that is all I was waiting to hear. So tonight after work I go to the busy tire dealer called Tire Barn. I wait there 1 stinking hour. The guy puts the car on the alignment rack. I tell him the issue. He says they don't do shims. I said why not and he says they just adjust the tie rods. So then I go to another place in town and the guy there gives me a hard time too. Finally he says ok he will replace the shims and align it if I bring it in tomorrow. So I brought the car home and just installed the shims. Was a bitch because the bolts' splines were rusted away so I had to grab the bolt and nut from both sides. If anybody actually read all this I applaud them.
 
Mine wasn't working either and ended up being a rotted vaccum hose. Double check all the hoses first then follow the guide at the vortex buicks site
 
My cruise control works perfect ONLY if I turn on the wipers....with the wipers off, no cruise control.....have had this problem since I put in a used steering column due to the big time damage the low life cowards did when they stole the car in 2001. Was going to use my .44 magnum to solve the cruise problem, but Grand Nationals are very expensive to replace....:jawdrop: So, I just live with it. Did get a new control stalk, but haven't had the time to replace it. Too much other worrisome stuff to do instead. Maybe someday.

Bruce '87 Grand National
 
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