ABS and Brake Warning Light Intermittent

[Iron Duke II]

My 1996 Ram 2500 w/12 Valve and 47RE overheated while climbing the grades on Arizona Highway 77 south of Globe, AZ, towing a 7K lb trailer. The transmission temp reached about 250 fahrenheit before I pulled over to allow it to cool down. Later in the afternoon while parking for the day the ABS and Parking / ! light stayed on while idling to cool down the turbo. Any ideas on what to consider while discussing these issues with my mechanic? Considering selling if I am not able to get the power and reliability back.

 

[KKohagen]

This may not directly apply, however hopefully it helps. On my just sold 2nd Gen 2002 it would do the same thing as described. It was one of the ABS sensors one time and the wiring another time. I have also had some dirt/grease on one of the sensors, cleaned it off, and no longer had it come in. On yours the rear sensor may be at each wheel or on the differential pumpkin.

 

[Iron Duke II]

I'll check the recommended areas out. Thanks

 

[surfbeetle]

My 1996 Ram 2500 w/12 Valve and 47RE overheated while climbing the grades on Arizona Highway 77 south of Globe, AZ, towing a 7K lb trailer. The transmission temp reached about 250 fahrenheit before I pulled over to allow it to cool down. Later in the afternoon while parking for the day the ABS and Parking / ! light stayed on while idling to cool down the turbo. Any ideas on what to consider while discussing these issues with my mechanic? Considering selling if I am not able to get the power and reliability back.

Did you find a resolution to this? I'm not trying to steal the thread but I feel that from a search point of view, adding my issue here would be relevant.

On my '95 which my daughter now drives, she told me yesterday that the truck was doing the same thing. I took it out and drove it and found that if I rev the engine, the ABS and brake warning light (same as parking brake is on light) will go out. Once the lights were out, I did a test panic stop and ABS worked as normal. Once back at an idle, the lights came back on and again went out with an elevated rpm. I was thinking that maybe it was vacuum related. Its been years and over 100,000 miles since I rebuilt the vacuum pump using the kit found at https://www.fixinrams.com/vacuum-pumps.html. I'm wondering if it needs to be done again.

Does anyone have any suggestions?

Thank you
Craig

 

[DavidC]

Test the vacuum at the pump and then down the line, maybe a fitting or hose, ac/heat selector switch.

 

[DavidC]

This may help with readings ?
https://www.dieseltruckresource.com...opics-93/how-much-vacuum-shoul-i-have-252220/

 

[Chief USA]

Check the vacuum line at the pump. My cat would climb up in the engine compartment to get warm and pulled the vacuum line off. The reason I figured this out was that my exhaust brake mysteriously stopped working. Electrically it was fine so I traced the vacuum lines back to the pump and the vacuum line was pulled off.

 

[Iron Duke II]

Perfect storm here on a combination of issues. Anyway, since this post my truck has been in the shop waiting on a good replacement P-pump. I won't get into the details on that, but the issue with the subject problem was the vacuum line going into the firewall. It had vibrated loose and fallen off.

 

[DavidC]

I knocked mine off while changing the oil pressure sending unit. I found out when the AC was blowing out the defrost vents.

 

[Brian Neal]

...
On my '95 which my daughter now drives, she told me yesterday that the truck was doing the same thing. I took it out and drove it and found that if I rev the engine, the ABS and brake warning light (same as parking brake is on light) will go out. Once the lights were out, I did a test panic stop and ABS worked as normal. Once back at an idle, the lights came back on and again went out with an elevated rpm. I was thinking that maybe it was vacuum related. Its been years and over 100,000 miles since I rebuilt the vacuum pump using the kit found at https://www.fixinrams.com/vacuum-pumps.html. I'm wondering if it needs to be done again.

Does anyone have any suggestions?

Thank you
Craig

I spent most of 2019 dealing with the intermittent ABS warning light and learned a few things...
just spit-balling here, but if your caliper pistons are sticking a little bit, then revving the engine might be increasing flow to the hydroboost, which might be applying more power to release the brakes...I'm not entirely certain if this is the case as the '95 has a slightly different ABS setup than the '01, but aging calipers might need some attention even if they are "working"...

 

[surfbeetle]

I spent most of 2019 dealing with the intermittent ABS warning light and learned a few things...
just spit-balling here, but if your caliper pistons are sticking a little bit, then revving the engine might be increasing flow to the hydroboost, which might be applying more power to release the brakes...I'm not entirely certain if this is the case as the '95 has a slightly different ABS setup than the '01, but aging calipers might need some attention even if they are "working"...

Thank you for the suggestion. I have found that the hard thin vacuum line was cracked under the drivers side battery. I did a quick patch with a larger hose around it and found that the issue was better but I don't have cruise control. I have to double check all of the vacuum lines and probably replace them, par for the course on a 25 year old truck. I did rebuild the vacuum pump back in December but my oldest daughter bought herself a car so now my middle one who was driving the '95 had taken over the Durango my oldest was driving. The 95 has spent more time just sitting. It's on my to do list but not quite as urgent.