ABS 'clunk' question

[dave110]

Hello all. So it's soon time for state inspection and like last year my abs and brake light come on just in time to give me something else to worry about. Last time they went out and have not come back on till now. What's different is I don't have the CLUNK when I turn the key to pre heat position. That clunk is the ABS pump right? Would a malfunctioning speed sensor cause it not to clunk or do I have another problem? I read the diagnostic article but it didn't address it. Also, I have contemplated just pulling the fuses and bulbs and running without ABS since I don't like it anyway. I read some guy did this and some time later the brakes locked up going down the road. I have a hard time understanding how that would happen, but could it?

[mopartechnician]

Most common problem with abs/brake light is the rear wheel speed sensor. Now with the noise you are hearing, I would unplug the abs module and turn the key on to see if the noise goes away. The intake heater relays will make a loud clunk noise when they turn off and on also.

[dave110]

The problem is I'm not hearing the clunk now. I should mention that my speedo and grid heater work.

[dobienut]

I've never noticed this clunk you speak of, but I just got done working on ABS issues. One post I read to help determine if it is rear speed sensor is jack the truck up in the rear and put it in gear and accelerate. If the speedometer functions and seems to function properly without huge spikes, it's most likely not that rear sensor. Mine ended up being the right front and I found out by getting someone take a scanner to get the fault. I replaced the line and no issues since. Very easy to swap the sensor out also

[dave110]

[. Very easy to swap the sensor out also

[dave110]

Well, I learned something today. I put a new rear speed sensor in and my lights went out. Shut off, and keyed back on and there is my THUNK again. So the noise is something to do with the ABS unit. Unfortunately it short lived and the lights are back on. I can sit in the truck with it running but not moving and watch them go out and come back on again. Sometimes when I back up they will flash on and off. But one thing's for sure.... when the lights are off the thunk is present at key on. I'm leaning toward the electronic part of the unit being bad. I'll try a little more but I'm ready to pull the fuses and go without. Thanks for the responses.