2nd Gen Non-Engine/Transmission Brake/ABS Light-- Problem Solved!!

[myneckbred]

Truck: 96' 2500 4x4, with 4 wheel ABS



For about two months I've been dealing with an intermitant nuisance. Most of the time, but not all the time, the brake/ABS light would blaze away on my dash. A check the rear axle speed sensor did not clearly indicated a problem. I ended up changing it anyway. Still the lights came on usually after diving for a short distance. Finally checked the vaccum system for a reading. At idle vaccum reading was right at 10 in of merc. With truck idling I moved my vaccum gauge downstream/away from the vaccum pump. As I went I would disconnect different systems. When I reached the small 1/8" vinyl line that entered the cab for the HVAC controlls and bypassed it my reading leaped to 25+ in or merc. The 1/8" vinyl line ended up have a chaffed section above the turbo. For now I cut out the chaffed section and replaced it with a piece of vaccum line. PROBLEM SOLVED. Chris

 

[Dane]

Good job!

Nice trouble shooting. Good info too...

 

[B.G. Smith]

What is the connection between the vac. leak and the ABS light? The 96 has vac. booster, right? Interesting. bg

 

[myneckbred]

Low vaccum sensor

On the trucks that still use the vacuum booster there is a low vacuum sensor. Apparently the leak in my system was right at the threshold of minimum vacuum requirements. Hence it was an intermittent problem. It would always occur in the same sequence. Brake light would illuminate followed shortly thereafter by the ABS light. If I was at a stop the brake warning light would sometime come on and I could throw a quick rev. and it would go away. However if I was in motion and the brake warning light came on the ABS light was soon to glow as well. I can only assume when the low vacuum sensor alerts to low vacuum the ABS system kicks out due to it's dependence on vacuum a source. Hope this helps someone else out. It was totally driving me crazy. I tried to scan the truck for OBD II codes but as it turns out the Kelsey Hayes ABS system can only be read by the Mopar diagnostic tool. What I ended up finding probably wouldn't't of even showed up with my luck. Oh well money saved... time lost. Chris

 

[Straight6Jeff]

I too have been staring at my Brake ABS light for about 5 months. I had replaced the VSS in the pumpkin as it was bad, but the lights still remained on. I had ordered the front VSS about three months ago. I finnally got around to installing them. Let me tell you, getting the old sensors out of a 2wd is really miserable. I had to take them out by breaking the main body off, removing the field coil, then use a 3/4 tap to thread intot he ferrous sleeve, then clamp a pair of vice grips on the tap, and use a huge pry bar to lever the sensors out.



Oh Yeah, no more brake/abs light or codes. The old sensors had small cracks in the very tips.



I purchased the sensors from Tenafly Jeep chrysler in NJ. They were about $35 cheaper per sensor than my local dealers.