Whether I am driving or whether I just start my van (2000 b1500) and leave it in park, at about 2 minutes exactly (maybe 2 minutes and 1 second since I start timing after starting rather than at first turning the ignition on), both my BRAKE and ABS lights come on. Doesn't matter if the engine is hot or cold they always come on at the same time.

So far I have done the following:
1. Replaced the sensor on the rear differential. I've done this twice.
2. Replaced the sensor on the transmission.
3. Pulled the ABS module (the Kelsey Hayes module, not the solenoid housing) and opened it up to look for bad solder joints. I couldn't identify anything wrong. Driving with no ABS module caused the speedo to stop working and one time (and one time only) caused a check engine light which gave a P0500 code. Also the BRAKE didn't come on because the ABS light never turned off after startup. I reinstalled the ABS module and speed started working, ABS light turned off on startup, but BRAKE and ABS still come on after two minutes.

So the only thing I can think at this point is that the rear diff sensor is functional but there is a break in the wiring. I'm not sure how I test that.

Also can't imagine it is the tone ring since it is doing this in park. I know there is a tone ring in there based on fingering through the sensor hole.

Anything else I'm missing?

 

Need to get the codes read, and see what it thinks the problem is.....

 

Are these abs codes you are referring to? Because neither of my obd2 readers show anything and the key dance just says "P none"

 

Hey,
maybe the brakelight switch, or the sensor/switch at the master break cylinder?

 

Yep. Will you code readers actually talk to the ABS module??

 

I would think that a broken wire to a sensor would trigger the light immediately after startup and not 2-minutes later. Also, the switch on the parking brake mechanism, although I've never tested in on my van, I know on other vehicles both the parking brake and the ABS warning lights will turn on, if the switch on the mechanism makes contact.

Most mid to lower priced code readers do not read ABS codes. FYI, a P0500 code on a Dodge indicates a Vehicle Speed Sensor (VSS) malfunction, meaning the PCM is not receiving a reliable speed signal, often caused by a faulty sensor, damaged wiring, or ABS issues. Common symptoms include a non-functional speedometer, erratic shifting, and ABS warning lights. Did you have this code before or after replacing the VSS on the transmission?

 

True!
I had the same problem, but I don't remember exactly what fixed it in the end. Corrosion on the differential sensor was definitely part of it.

In that regard: grab the wiring diagram, find the right pins, and measure the signal and return lines to the sensor (with the sensor disconnected and the wires shorted) to check for breaks or contact resistance, in case it isn't the sensor.

 

I'm not aware of a master cylinder sensor, at least not on the fluid reservoir. Can you be a little more specific?

That's a good question. They don't talk to it. So the question then is whether that is because they can't because they aren't capable or because the ABS module is dead. I would think that if it is dead then the ABS light on the dash wouldn't turn off after startup, but maybe it really does just take the ECU 2 minutes to check in with the ABS module, at which point the module doesn't respond so on come the lights. I could pull it and send it to one of those repair places but I would hate to drop $150 plus shipping if it isn't the problem.

Also, the ABS module must be doing something because disconnecting it causes a check engine light, a P0500 code, and the speedo to stop working.

I have tried disconnecting the parking brake sensor from the parking brake pedal and it didn't change anything. I know that sensor works because BRAKE comes on when I press the parking brake pedal and turns off when I release the parking brake.

Yeah, both the scanners I have tried have claimed to read ABS codes, but who knows whether that is true or not.

The P0500 came after I disconnected the ABS module. It was accompanied by the speedo not working and a check engine light. Reconnecting it seems to have resolved those issues. The P0500 came before I replaced the VSS on the transmission. It was also resolved before I replaced the VSS on the transmission (by reconnecting the ABS module).

Also, when people online say that it might take the dealer to be able to scan the ABS. Are they talking about the DRB III tool? Does that even apply here or would I just be throwing money at a dealership?

 

2 or 4 wheel ABS?

 

2. I think anyway. 2 wheel drive. Front disc brakes, rear drum, I think.