My dads ABS isn't working. We've checked all the fuses but the ABS light stays on, on the dash and the Brake light. The brake is disengaged and if he's in the driveway he can put on the brakes and the tires will lock up. Also when his truck is idling for bout 30-60 secs it starts to vibrate the whole truck and if you pop the hood you can see the engine bouncing back and forth. It's been doing that for a while though and hasn't gotten it in the shop and now his warranty has expired so he's wanting to know what it is and how much it will cost before he spends too much money having people look at it and tell him that they couldn't find anything. Also every once in a while we'll be going down the road and then there will be a loud humming sound but if you let off the gas then get on it again it stops. I'm confused, lol. Please Help.

 

Assuming the brake system and the parking brake light switch is ok, you might have an ABS module failure. The ABS system needs to be scanned for codes, if a code for a ROM failure is listed, the module is bad. The module is about $300 - $350, and then you need the dealer to re-flash the axle ratio and tire size codes into it ( another $92). I know because I encountered the same problem. And that is what it costed me to fix myself..

 

My money is on the Rear Speed Sensor. Its on the rear diff. Replace that and your problem will probably be gone.

As for the idle give your throttle body a good cleaning, especially your IAC motor (on the back of the throttle body). You'd be supprised how much gunk gets in there.

To clean it pick up a can of carb/tb cleaner for $3 or so. Take off your air cleaner and disconnect all the conecters on the TB. On one the right (TPS sensor), one front (MAP sensor), and one the back (IAC Motor), and the 2 or 3 cables on the left off. Next take the screwes on the top of the TB off. The whole thing will pop right off. Take off the TPS, MAP, and IAC. They each are held on by 2 screws. Now just hose the whole TB down and clean it up really good. Make sure to get ALL the crap out of the IAC hole. Now take a rag and soak in it the cleaner and clean the IAC itself.

That should take you about 20-30 mins. Do that and let us know if it helped

It could also be your ignition system. When was the trucks last tune up?

 

Thanks guys, I'm not sure when the last tune up was cuz he bought it from the dealer bout a yr ago but the person that had it took good care of it. (even has a MOPAR battery ) We have to work on a house this weekend but we'll try to do the things you guys suggested. Thanks a bunch.

 

yep id say for the abs its the rear speed senser i dont think the idling vibration has anything to do with that, just give her a good tune upo and see what happens

 

proly be smarter financially wise to start with the rear wheel speed sensor.. then move onto the ABS module

 

Another Question, the A/C wasn't working so we changed the fuse cuz it was blown but it still doesn't work. BTW, in the summer when we have the A/C on and the truck is idling it will sometimes die. It will start to die so we revv it up a bit then let off the gas and it dies.

 

just throwing this out there but you may have a vaccum leak somewhere. it would cause the rough idle and it would decrease the effectiveness of the brakes... but i dont know about them locking up. Its just an idea if the other stuff doesnt work.

 

My money is still on the IAC. Clean it up!

It controls idle, along with some other stuff.

 

i agree check for a vacuum leak 1st if it is it is the cheapest to fix. As for the a/c the clutch might not be fully disengaging and thus putting a load on the engine at idle.