Just bought a new to me 2001 Dakota Sport 3.9L and found something that was unplugged in the engine bay. When i plugged it in, it made this loud buzzing. I have searched and have no idea what it is other than it has to do with the brakes:/ i took a video of it. if anyone can help, it would be greatly appreciated!!!

 

Welcome to the forum....

It's the rear ABS controller. There must have been some problem with it in the past and the previous owner just disconnected it instead of fixing/replacing it. Just from reading the service manual it looks kind of involved, if you have to replace the controller it has to be programmed to your rear axle and rear differential, it monitors the revolutions of the gears in the differential to decide whether to engage the ABS. The manual says the programming has to be done at the Dodge dealer with the DRB3 scan tool. I have to wonder though if a good brake shop might be able to check and program it. I *believe* the rear brakes will function normally like non-ABS brakes with the module disconnected. Someone else here will know the answer to that one...

Jimmy

 

It is the CAB, controller anti-lock brake. You have 4 wheel ABS.

It will cycle when first powered up. What happens if you leave it connected? It seems to shut off as it should. Are there any warning lights on the dash?

The easiest thing to do is get the system scanned for codes. Very few code readers can read ABS codes so this means dealer or a well equipped brake shop. The DRB can test and actuate the entire system.

 

OP has a 2001 Sport. My own truck is also a 2001 Sport. Mine only has rear ABS, which is why I believed OP has the same rear ABS. The dealer, brake shop or build sheet for his truck can tell OP for sure what brake system he has. The service manual says:

CONTROLLER REAR WHEEL
ANTILOCK BRAKE
DESCRIPTION
The Controller Antilock Brakes (CAB) is a microprocessor
which handles testing, monitoring and controlling
the ABS brake system operation (Fig. 3). The
CAB functions are:
• Perform self-test diagnostics.
• Monitor the RWAL brake system for proper operation.
• Control the RWAL valve solenoids.

Not to confuse or give OP any wrong info, but this is the info on which I based my reply to OP. I am by no means a brake expert but I agree and would hope that a good brake shop might be able to read the brake codes. I would only take the truck in to the dealer if I absolutely had no other choice.

Jimmy

 

You can have 4 wheel ABS with a Sport, I do. It's an option, just as the Sport package is. His video clearly shows the HCU and CAB.

There are no pumps with RWAL brakes. What I hear is the pump running when he first plugs it in as well.

You can get rebuilt CAB's already programmed for your vehicle but I'm still curious as to what happens if you leave it plugged in.

 

So you are saying plug it in and wait and see if it stops after a few minutes worth a try I guess.

It may be an initial power on thing that goes away

 

Thanks for the advice, when i leave it plugged in it doesnt go away, it will stay on and it seems like my abs brakes are constantly on while driving. the rear drivers side wheel will lock up, squeal, then lock up again.

 

Are your brakes in good shape?

I would pull off the rear drums and inspect them very thoroughly check the cylinders for leaks look for wet spots binding make sure everything is in order.

Are the front ok.

Check the ABS/speed sensor on your differential or just replace it.

Just make sure everything is ok with the braking system mechanically first.

A complete DOT 3 flush may be a good idea as a precaution see how the DOT 3 looks is it black?

I'm not sure how you check them but check each wheel ABS sensor you may have a bad sensor check the wheel that's locking up the rear is the sensor on top of the differential I believe

You may have all wheel ABS or two wheel meaning only the rear has ABS

 

If the noise continues, it's in the controller. There is a relay in there and the contacts fail. It can be rebuilt. You don't have to remove the lines, just the top module.

 

The brakes are all new, just did them myself, fluid is fine as well, i think im just gonna take it out