ABS / Brake light on

[jlopezpe]

My truck is a 1990, D 250, 2 WD. When I apply the brakes slowly the light comes on. If I pump the brake pedal I'll feel a pop through the brake pedal and the light(s) will go off. I bled the ABS unit and it seem to improve some. I found the parking brake to be in need of adjustment, but it broke in the process. The new one is on the way. I'm worried that the brakes are going to fail.

 

[paccool]

Leaking brake booster will cause the light to come on. Are you having any trouble with the cruise control? It also uses vacuum. When my 93 was acting up, several closely spaced brake applications would drop the vacuum and the truck would be hard to get stopped. Hold the brake for an extended period of time at a long stop light would also cause problems.



I put a vacuum gauge on the hose that went to the cruise module and checked the reading. Should be around 20. Mine was low. The main hose and the cruise hose both connect at the booster so take the plastic fitting out of the booster that the two hoses hook to and plug off with your finger the hole that goes to the booster. If the reading goes up, its the booster.



Now, having said all this, there are other things that can cause the symptoms you have. The booster is an easy thing to check, will take 5 minutes or less. If it is something else, I would check the master cylinder for problems

 

[jlopezpe]

I do not have a cruse control (wish I did though), but will check the booster. The master cilinder does sound like a good one, thinking about it. If one of the seals were bad it might act as a leak switching the braking to the oposite side.



Thanks. I'll keep you posted.