On my 91 D350 the antilock light and the brake light are on. The brakes seem to work fine but you can hear air when u hit them. I am guessing I have a vaccum line with a hole in it. Any ideas about why these lights are on.? I noticed the brakes can act kind of goofy sometimes. Thanks.

Justin

 

Sounds like a bad vacuum booster.

 

i dont think the booster will throw those lights though will it? that tells me to look at the sensor in the rear end.

 

If there's a vacuum leak the vacuum sensor kicks the red brake warning light on.

 

It probably is a leak but I do know on my 89 both lights stay on if the brake fuse blows.

 

On my truck the lights are turned on by the sensor located on the left fender well below the hood hinge. As far as I can tell the sensor monitors vacuum.

 

I replaced my booster and lights went out. Low vaccume will cause the lights to come on and make a musshy brake peddle.

Greg

 

My light has been on for a couple of years now. Can't figure it out. Brakes are good and the peddle is firm. I hear the vacuum boost working but but the red light for the brakes never goes out. Idono?