I need to wrack you peeps brains a bit

So just finished up my rebuild of the engine a few days ago and amongst the rebuild I changed everything (that I could get my hands on) on the front brakes cause they needed love. This includes calipers, pads, rotors, brake hoses, and masters cylinder and fully bled. The only thing I haven't changed was the brake booster and the abs module (which has been dead for years even before the rebuild)

Now my issue is that the brakes work fine for the first few minutes of driving but then only the front ones engage and start dragging, key reaction is the truck will have a hard time shift (making the fresh engine break in difficult)

I pull over, turn off the engine and restart and it immediately goes back to normal for a few minutes but repeats. Can anyone shed some light into this?

I'm pretty sure it's not the abs module because it's been unreadable from the PCM for the last 5 years, but covering all my bases. I was thinking brake booster, but if that was the case, wouldn't the dragging be a constant issue instead of intermittently?

I'm hoping it's not either because they don't make them anymore and hard to get ahold of, maybe it's just something stupid that I overlooked?

 

Did this problem start before, or after you did the brake work?

 

It started after.

 

Then the problem is coming from something that happened during the work. Is the ABS system still powered? 2 or 4 wheel ABS?

 

The abs never had power, as far back as I've had the truck it has been unable to communicate with the ecu or be brought up on a obdII reader, and it's a 4 wheel abs

You might be onto something though... since they only rely on the abs module and only effect with the antilock brakes and the new front ones are the only ones affected, and guessing since the new sensors can't communicate with the dead/faulty abs module. wouldn't disconnecting the abs connector wire going to the calipers stop the random binding cause by the abs while still allowing me manual braking power until I can find a replacement abs module?

 

If the ABS isn't powered, the sensors shouldn't matter. If, however, ABS simply won't talk to your scanner.... that's an entirely different kettle o' fish. Is the ABS/Brake lite on?? Does the ABS system self test when you start rolling?

 

The abs light has been a constant as long as I can remember. It could just be the abs module is faulty in on its own as well as not reading from the obdII? It could be powered but idk at this moment I'm gonna run around the neighborhood with them unplugged for now see if that causes them to still grind after a few minutes and if that's the case then I'll know it's at least abs or the pcu communication issue or just faulty module. If not then my money would be the booster just can't keep pressure

How would I know if the abs self tests? That's a new one for me.

 

The booster just gives you an assist when you step on the pedal. If you aren't getting assist, it's like stepping on a rock, and you REALLY gotta stand on it to get the brakes to do anything at all.

Don't think I have ever seen a failure mode where the booster actually applied the brakes when you weren't on the pedal..... and the timing is awfully suspicious.... If it wasn't doing it before, it is quite likely that it is NOT one of the parts you DIDN'T replace.

 

Do you have 4 wheel or RWAL abs?

 

So I can rule out the module. Front two were unplugged and it still started grinding after a few minutes.

That might be a possibility, I gotta wonder if I purchased incorrect calipers or pads. But if that was the case, wouldn't the binding be a constant?

It's 4 wheel

It's either the something I purchased that is faulty/ incorrect or the last possibility I would think would still be the brake booster. As far as I'm aware this brake booster has been in the car for 15+ years, cause I've never changed it since owning it. Is it possible that the new and correct vaccum coming from the freshly rebuilt engine was the braking point for the diaphragm inside the booster and caused a tear inside that will start to build vacuum but slowly lose it over time? 🤔