2nd Gen Non-Engine/Transmission ABS Pump will not shut off! :mad:

[CrewCabDiesel]

Today I was driving around working on our schools baseball field and I shut off the truck and heard a electric motor running under the hood. The ABS pump motor just runs and will continue to do so until I pull the fuse for the ABS pump. I tried disconnecting all the wiring harness from the ABS pump and it will only shut off after I have pulled its main power feed. The dash lights for both the "ABS" and "Brake" lights now on and I don't get any codes. I will later try using my scan tool to see if I can get any hidden codes. Anyone have an idea whats broke? The truck now has 207000 miles and the brakes work great.

Thanks

Kyle

 

[WDixon27]

not sure how the dodge pump is set up but it should have a relay for the pump motor somewhere, it's probably stuck, early bosch units have it on the pump under a plastic cover

 

[jmy]

CCD

When your ABS motor runs all time it is usually a mosfet driver shorted on your ABS electronics controller board.

The ABS elect. controller board is mounted on top of the ABS pump/hyd. unit.
The ABS elect. controller and solonoid assy comes off as a unit by disconnecting the plugs and removing the four torx 8 screws holding the controller to the ABS motor/hdy unit.

You can't get to the mosfet to replace it without special tooling because the unit is sealed.

The ABS elect. controller is programmed for use based on tire size and gearing.

At one time the dealer had to program the ABS controller when a new controller was installed.

Times have changed and now you can get a new controller from the dodge dealer that is pre-programmed for your truck based on VIN #.

I've also replaced defective ABS controllers with used controllers with good luck. A used controller to match your truck may be hard to find. If you do look for a used controller you will need to reference the two numbers on top of you original controller to get a match.

The ABS controller interface is not ODBII. You cannot read the ABS codes with a regular scanner. You will need access to a dealer type DRBII / III to read the codes and operate the ABS diagnostic functions.

Some higher end auto shops have scanners that will read ABS codes however, many of these scanners show only generic ABS codes which can be misleading in diagnosing problems on the dodge ABS.

Last time I checked the new controller, through some of the online dodge discount dealer parts houses, were ~ $380. 00 at discount.

A used ABS controller for the Dodge HD pickup, if you can find one, usually goes for $150. 00 - $200. 00.

 

[jmy]

CCD

One other thing, when you remove the 40 amp ABS fuse. The spring loaded solonoids inside the ABS hyd. unit are set to a neutral position, ABS is disabled and brakes work as if no ABS is installed.

 

[CrewCabDiesel]

Well it seems I will need a new ABS controller, anyone have an idea where I can find a used one? Also has anyone installed a bypass switch to shut off their ABS? I had forgotten how nice it is not having ABS is on dry pavement.

Thanks

Kyle

 

[CrewCabDiesel]

The new ABS controller came in today and the I now have the ABS brakes working but I now have a flashing ABS light and no codes, any idea whats up?

The controller is brand new from dodge and I have tried disconnecting batteries for a while with no results.

Kyle

 

[Gary - K7GLD]

Man, this is the first I have ever heard of an "ABS motor" - where is it actually located?

 

[BJMarshall]

Gary, have you ever had your hood open?

CCD, You may want to go back to the dealer. I have only installed one new one from a dealer and it did what you are saying. All the others were used and I made no effort to see if they were the right ones and they all worked fine.

 

[Gary - K7GLD]

Gary, have you ever had your hood open?

UMmmmm - well thanks for the informative and helpful reply...



I've noticed THIS ABS assembly underhood, but was not aware that there were any electric motors involved, which was why I asked:





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- but ask a simple question, and get a foolish answer...

 

[easleyj1]

Gary,

Drivers side fender well back next to the firewall, has a silver top with two plugs with a small round motor underneath. The motor points toward the opposite fender.



Jonny

 

[Gary - K7GLD]

Gary,

Drivers side fender well back next to the firewall, has a silver top with two plugs with a small round motor underneath. The motor points toward the opposite fender.



Jonny

I'll have to take a closer look into that area, thanks Jonny. I've spent LOTS of time messing around underhood with the fuel system on this truck (and some other systems!), but spent little time paying attention to the ABS and rest of the braking system - that's why I am mildly surprised about the motor bit. I assume the motor is used to somehow modulate/control braking as applied to the wheels - wonder if it is designed to only control front vs rear wheels in pairs - or to control each wheel independently of the others?

 

[jmy]

Gary,

You are right it does modulate and control.
The ABS motor controls the braking in the same way someone might pump the brakes before the days of ABS. A cam on the motor shaft controls the pumping action the ABS microprocessor has PWM signals that drive electromics to controll solenoids that open an close valves to each hydraulic line. The microprosser also gets input from the two front wheel sensors, the rear sensor, the speed sensor, brake pressure and a few other things to decide how to modulate the valves and when to turn the motor on and off.

The valves are spring loaded so when the ABS motor fails, or some other ABS error is detected, the ABS unit goes into a fail safe mode and the springs return the valves to a netural position allowing the brakes to operate as non-ABS brakes.

 

[NWhitney]

Had the EXACT same thing happen to my truck last fall. Shut the truck off and you could still hear the ABS pump running. Took it to the dealer and after $60 told me I needed a new controller. Ok great how much? Oh just $320 for the controller and if we put it in total bill just under $500.

I may be some dumb but I am not plum dumb so they orded me a contoller and I put it on. Same thing Little ABS Yellow light kept flashing at me and the ABS did not work. Back to the dealer I went.

Dealer: Oh yeah those are shipped with out programing you will have to pay us another $35 to program that controller for you.

So that is the end of that dealer for me. I guess from now on I go to the dealer that is 5 miles farther away!!