I'll start by saying hi to everyone since this is my first post. For the most part I just browse for info but here is my problem.

I have a 98.5 ram 2500 4wd.
I'm getting ABS codes 78 and 82.
Tachometer works just fine, went ahead and replaced the rear sensor anyways just to be safe and it was inexpensive.
Flushed brake fluid and topped off.
Rear brakes are adjusted and everything is in limits

But when I lift the rear off the ground I don't get enough pressure to stop the wheels at idle. Now I was thinking of replacing my rear cylinders, but I noticed the pressure indicator on my rwal???? Valve won't stick out but the one on my combination valve does.

Does this mean the ABS system has disabled itself or is there a bad wire somewhere maybe? Any info will be help full thanks.

Tim

 

On a side note is there a way to bleed the rwal valve?

 

Well no one else has posted anything, but maybe someone can tell me where the ABS controller is? I read in another that it was under the glove box but no one specified years or Gen for that location. I have some sort of box up by the rwal and combination valves.

 

I'm not sure what those codes are.....and I'm sure no one else does either which is why no one's responding. How did you get the codes you're talking about?

 

78 was a general brake code basically saying there is a problem, 82 is ring tone out of reach, but looking at it, it seemed brand new. No wear marks. Plus the speedometer works just fine. I had my buddy pull the codes with a snap on scanner.

 

I guess I'm not familiar with such codes since all the codes I have in the service manual, nor have heard of, start with a "p" and are followed by four numbers. Example: p-xxxx

 

Ya my understanding from the internet is that pxxxx is pulled from the ecm and the two digit codes come from the abs controller. I know this I can pull the four digit codes with a superchip but require a shop grade reader for the abs codes.

 

Diagnostic test for code 78 maybe of some help. You will need Adobe Reader
If no pressure to rear brakes possible master or brake hose at rear axle damage or colasped internal. Try disconnecting before hose to see if you get brake fluid pressure there. If you do replace the hose

 

Thanks bigiron,
Steps 19 and 20 should prove useful. Lastnight I got myself to 17 just messing around with it. I'll update you on the results as soon as this storm clears up.

Tim

 

One time my ABS/brake dash lights were on and it turned out that the brake pedal switch under the dash was faulting. $50 and 10 minutes and all was good.