Pacbrake PRXB Not engaging

[RScaletti]

Just installed a pacbrake a week and a half ago. Worked perfectly from day one until yesterday. Today, it won't engage at all. Truck just coasts as if it wasn't even installed. Everything looks to be tight and connected.



Any ideas? Fuses or relays?

 

[SBashaw]

Start simple, Check to see if you have power to the compressor and if you do does it run, no air pressure = no pac brake! More than likely just a loose wire if it was running before.

 

[JFought]

also, i had a really hard time to push pin all the way to bottom out in the wiring harness.


if power and air exist, then check the wire you installed to factory computer harness

 

[Prairie Dog]

The only thing I've ever had fail was the relay on top of the pump assembly. I was able to get another one from Napa for about $17. I chalk up the failure to the heat it suffered when mounted on top of my engine where they suggest you put it. I'v since moved it to the empty area behind the passenger battery where it's much cooler.
You can put a simple wire across the relay socket to check its operation. If it works with the wire then the relay is crapola.
Of course I'd be surprised if it failed after only a short time.

 

[RScaletti]

Yep, pump is not turning on. Now to find out why...

 

[Prairie Dog]

Ground the wire going to the switch, if it turns on then there's a loose wire in the switch circuit.

 

[RScaletti]

Blown 30a fuse in the positive battery wire. Replaced and good to go. Should I be looking for another problem that caused the fuse to blow? My install is EXACTLY per pacbrake's instructions.

 

[Prairie Dog]

I would look for what ever caused the fuse to blow - they don't fail on their own.
Is there any chance the pump froze? I had this happen once but it didn't blow the fuse.

 

[DMather]

Although you always want to know why a fuse blew.....

It's a new pump... maybe a bit stiff and drawing a bit extra. It will either get better or worse. Ammeter can tell for sure.

If the fuse was mounted in such a way as it was taking a lot of vibration..... Under load or even while off, vibration can kill a fuse prematurely. And I just hate it when my fuse blows prematurely.

And... . make sure that your engine compartment has not been contaminated by buss-mites. They love to make snacks of inline fuses. If this has happened you will have to make sure you an amp-le supply of re-volting puns to drive the little circuit breakers away.