Had Tune-up And New Brakes Put On...but...

[1991LS400]

Hey guys, :(

Yesterday I had my mechanic put on new front and rear brake pads, resurface my rotors, and do a tune-up including new NGK spark plugs, ignition wires, rotors and caps.

Now, while I'm driving the emergency brake light stays on but when I'm idle or braked it stays off, however, my car makes little jumps here and there. I'm not talking about lurching forward, it just makes little hesitant jumps and shakes while I'm idle or stopped somewhere.

I thought it was coming from the brake system but I got out to look at my engine while it was idle and it seems like everytime the car jumps the engine jumps too. It has nothing to do with the mounts, so please, no one talk about mounts.

It started happening after my mechanic put new front and rear brake pads on my car, resurfaced my rotors, and installed new spark plugs, wires, rotors and caps. So something had to of happened during that process.

Any ideas as to what could be causing the parking brake light to stay on while I'm driving but stay off while I'm idle and why my car is making little jumps and shakes while I'm idle?

Please help.

Brian

[SRK]

Sounds like the engine has a partial misfire. That can be from a plug wire not properly installed, or a closed up plug gap, maybe from dropping it during install. Have him test the ignition system on an oscilloscope to identify the cylinder.

The park brake light may be from having the park brake adjusted too tight.

[blake918]

Any ideas as to what could be causing the parking brake light to stay on while I'm driving but stay off while I'm idle and why my car is making little jumps and shakes while I'm idle?

Do you have enough brake fluid in the reservoir?

[1991LS400]

Yes, there's enough brake fluid in the reservoir but I have to do a flush on it tomorrow and refill it because it's black. Anyway, the DOT-3 brake fluid shouldn't have anything to do with the parking brake light.

Brian

[vyhanh]

Have you checked the Throttle Body Sensor (ie is it clean) ? Has the MAF been put back properly (with all hoses properly tightened) and no damage?

[1991LS400]

MAF is?

[mbpgawest]

MAF = Mass Air Flow sensor Located near the air cleaner box.

If the brake fluid level is low the brake light will come on. What does the light look like that is on?

[1991LS400]

It is the parking brake light. Because when I step on my parking brake the light comes on stating that it is ON but when it's released it's supposed to go off. It has an exclamation mark in it.

[VMF]

FYI, no aftermarket "brake fluid" or "steering fluid" should be used or you risking to destroy lots of parts. ATF fluid ONLY!

[blake918]

Anyway, the DOT-3 brake fluid shouldn't have anything to do with the parking brake light.

Brian

Yes, it does. I'm not talking about the type of fluid but the level. If the brake fluid is low the parking brake light will come on until it is at the proper level(thanks, Mark ;) ).

[1UZ-FE]

blake is right. read your owners manual.

[silvermate]

yes the other members are correct...........the sensor in the brake fluid resovoir is very very sensitive, if its even a 1/4 of an inch below (maybe even less) the brake light will come on..............

i had this happen about a year ago, i added fluid back up to the full line, and the light went off ;)

[jampak]

I'm having the same problem with my '92 LS 400. It also started after replacing the brakes. In my case the jerking is mainly in the rear. To this day, I still don't know the cause!