Q: Help! I just had the scariest experience of my life.
I was driving on the freeway in my 2000 GMC Yukon with the cruise control on and attempted to turn it off at an off-ramp. The brakes felt funny and weren't slowing me down, and the engine began racing. I pressed as hard as I could on the brakes, but with the engine going full throttle, the vehicle wasn't slowing down fast enough.
Luckily, I had the wherewithal to turn off the key and was able to safely pull to a stop. I restarted the engine and drove straight home without using the cruise control and had no problems.
What in the heck happened? I'm afraid to drive the truck again until I know for sure the issue has been fixed.
_Jake A.
A: Wow! Good job having the mental composure to turn off the key and cut engine power!
I have a strong hunch your stop light switch is the cause.
Please check to see if the Yukon's stop lights work as you press the brake pedal to various depths. I believe you'll find they don't, and that's related to why the cruise control failed to cancel and poured on the coal as you attempted to slow.
I am not a fan of this switch design, which was used from 1994 to 2002, as I've encountered several instances of flakey operation and the part is absolutely miserable to access and renew. In your case, the fault isn't likely with the switch's electrical contacts, but rather the way the part senses the pedal-brake booster rod connection and interferes with brake operation. It's possible, also, that the switch's retaining clip has come loose. If the brake lights are found to not be working, drive carefully straight to a repair shop, using the hazard lights as needed to keep folks behind you informed you are slowing or stopping.
Q: I hope you can tell me what might be causing my 2011 Buick Lucerne to sometimes not start. It's also quit on me twice but has started back up and run fine after I've had my mechanic check it. He thought it was the fuel pump and replaced it, but that didn't fix it. This may be a coincidence, but it seems to be worse when I am going places with the family. This of course makes the situation worse with unhappy kids! There have never been any codes I've been aware of.
_Gerald F.
A: This is a long shot, but there could indeed be a connection between the car's misbehavior and having your family aboard. Or maybe not.
GM released a service bulletin (15-NA-051) last year speaking to a condition that can lead to electron mischief affecting engine performance. The rear seat bottom frame may come into contact with the rear electrical center, which is a fuse box beneath the seat on the driver's side, causing the fuel pump relay's terminals to develop connection problems.
Try this: With the engine idling in park and the parking brake set, try bouncing around in the left side of the back seat. If this causes a stall-out or change in engine operation, we're on the right track. The fix is to replace the fuel pump relay with a low-profile version ( 88953222) and trim the seat bottom frame slightly using a cut-off wheel or similar, so it better clears the REC.
