Funky Brake Pedal, Loose Seat.

[Kellie]

My boyfriend and I just picked up an '02 1500 HD with 86,000 miles yesterday. This is our first truck and we both have limited experience with GM vehicles, so before I take it in to the dealer for what might be normal or easily fixed at home, I wanted to ask about a few things I've noticed.

 

When I start the engine and my foot is on the brake pedal, the pedal jumps back before it sinks down. It's really odd, I showed a few friends (who also know nothing about these trucks) and they had never seen anything like it either. My first thought was a booster problem, but I wanted someone else's input. The brakes act perfectly normal while driving, it's only when I first start it that the pedal does anything unusual. I did a search and couldn't find anything similar.

 

I noticed that there is some play in the drivers seat. When I accelerate, it slides back just a tiny bit, and when I slow down, it slides forward. It's really minor, but it bothers me. I did a search on this one too, and found a few similar problems. I work on BMWs for a living, and some of their cars do the same thing, but it usually means the entire seat base needs to be replaced. Hopefully that isn't the case here.

[bill190]

As to the brake problem, might want to put a vacuum gauge on there (if this is operated by vacuum) and see what is going on with the vacuum when it first starts.

 

Also my memory is not the best in the world, but a long, long, time ago, I seem to recall something about a brake booster check valve? Something which would only allow air (vacuum) to flow one direction?

 

Anyway if it is vacuum, and there is a check valve, maybe the check valve is not "checking"? (This was on a much older vehicle, don't know about yours specifically...)

 

As to the seat... Unbolt it, turn it upside down, and see what is going on under there!

[Kellie]

I'll bring home my vacuum gauge and give it a shot. I've had that thing since automotive school and NEVER used it! I'll inspect the lines (I haven't even opened the hood yet), and see if I find anything unusual. Thanks for your help!