440forPOWER

Hello, last fall I had the anti lock and the brake light come on in my 93 2wd. They went off right away but now they come on about every week or so. But they always go out right away. I was just curious what triggers these lights to come on? Also it seems like they go on more if I go up an incline. They have turned on twice when going up an off ramp on the interstate. Don't know if thats because on the incline or the stopping from a higher speed. Any help would be greatly appriciated. Thanks

SOOT4BRAINS

Anti-lock light and brake light on at the same time is an indicator for low vacuum. There is a vacuum sensor that has a line that goes right to the brake booster. One big line from the vac pump to the booster, one smaller line that goes from the booster to the drivers side to the vacuum sensor and one tiny one that goes inside for the hvac system. May just be a cracked old line, could be a bad booster, or a vacuum pump in need of a rebuild. Good luck!

Aaron

The_Head

Mine does this too but only when it's cold in the winter time.

raggmann

Mine does it if I'm sitting at a light or whatever and have my foot on the brake peddle for any length of time.
I'm not too concerned as the brakes work good, it's just when it's sitting.

HappyCamper

The spec on the vacumn is 25-8.5 Hg. When the vacumn is less than 8.5 for 10 seconds the brake light comes on.

If me, I would check this one out if I were seeing the lights com on. That could be a precursor to a vacumn booster total failure and the brakes do get much more difficult when that happens. But then, my friends know I am a little **** about maintenance and repairs.

cougar

That is when my 92 does it. After the truck has been on the road a while and warm, I turn it off and restart. No more lights. I am wondering if there is moisture in the sensor or line that is freezing.

ofcmarc

Mine did the same. the colder it got the more often the light would come on. I found a vacuum leak in the booster and replaced it now the light stays off.

440forPOWER

Thanks guys, I'll check it out when it gets a little warmer out. I did a rebuild of the vacuum pump about 2 years ago. So that should be ok. Just curious where the best place would be to hook up a vacuum gauge to check it while running. Big line going from pump to brake booster to see if the pump is creating vacuum? Thanks again

sdseva

i hooked a vac gauge up to where the heater control line goes on the top left of the booster. i found it was leaking, replaced , and my brakes are back. the lights are still on but i think its because the rwal sensor connector broke of the sensor itself

cougar

Where your brakes working normally? Reason I ask is because my brakes and heater control work normal, no hissing noises either.

Rickcher

I don't think vacuum is the only reason the ABS and brake lights will come on. This is from the "Sticky" https://www.dieseltruckresource.com/...ad.php?t=59092
My ABS and brake lights have been coming on lately and I have a "9 flashes" code. Haven't been able to find the bad wire yet, though.

ofcmarc

Yes. Although if I had to manually pump the brakes instead of waiting for the RWAL to kick in it would only give me 2 maybe 3 presses before the lights would come on and I would be out of assist.... NO hissing or heater problems either.

freight train

Try the abs sensor harness that comes off the pumpkin and goes up to the frame. There is a connector there that corrodes and causes this. I have repaired this on two different trucks and the lights went by bye!!!

sdseva

where can i get the connector end itself? it broke off in the sensor

freight train

I bought a whole new harness threw dodge once. I dont know iff they are still available but here is the #4487030. The problem is getting it out of the sensor.