A few days ago, after my tranny was rebuilt and reinstalled, my Pac Brake started blowing the main 30 amp fuse. That may have been a coincidence, because I have no reason to believe the two events are connected. Anyway, I've been unable to identify where the short is. Now the fuse is remining intact, but nothing works. I've verified 12+ volts at the fuse and all the way through the fuse holder. There is power to one of the terminals leading to the controller, but I don't know where to check after that. The compressor does not run and the on/off switch in the cab appears not to have any power to it; at least the LED does not illuminate. I'm confused and I'd appreciate any suggestions on how to troubleshoot this thing and get it working again. TIA for any comments.

 

Have you checked to see if any wires were caught between the tranny and block? That almost sounds like there is a pinched wire since it started after the tranny was pulled and reinstalled.

 

There is a small loom of wires (2 or 3) coming down to the connector on the side of the transmission. I haven't been able to get it up on a lift yet, but I crawled underneath and looked as good as I could. The splices appear to still be in good shape. I should further clarify that the compressor would run and build proper pressure in the tank. The fuse may blow while the compressor was running or the Pac Brake may work all day without the fuse blowing. I couldn't find any consistent reason for the fuse to blow.

 

Lets narrow it down a bit. Can you attach an outside source of air, like a portable tank, and drive the truck to check the operation of the brake? If it works correctly, that narrows the problem down a bit. Since you had the tranny built, a reputable shop would have pulled the battery terminals before starting the removal of the transmission. I'd check the terminals just to make sure all your connections are correct.

 

We're in the middle of a trip right now; in Montana headed back to Iowa and I'm having to do my "maintenance" when we stop at a campground each afternoon. So I may be able to find a way to air up the Pac Brake tank this afternoon. I'll triple check the connections, but I'm pretty sure power from the battery and groiunding are not the issues. Thanks.

 

I think I've found the problem(s). 1) the wire coming from the ignition source has a break in a splice; i.e. the control switch and everything downstream from it could not function. 2) The compressor is failing. I was able to power up the compressor but after just a short while it started making some pretty wierd noises that led me to believe it was slowing down and close to siezing up. I think this is creating increased resistance on the motor and causing the main fuze to blow. If this is the case I'll need a new compressor and, from what I've been reading, may be well advised to relocate the compressor.

Does this sound reasonable. If so, where do I get a replacement compressor? Thanks for any comments.

 

You can get a replacement through Lary here at the DTR store. Make sure he knows you're a member. As to the fuse, I'd change it to a circuit breaker. Is there any way to check the oil level in that compressor?

 

No oil in those compressors. If you don't already have the upgraded Puma replacement compressor, I'd highly recommend that you get it. It performs much better than the original Viar units. As well, check for system leaks. The compressor won't live a long life running beyond its duty cycle because of leaks. It is common for a worn out compressor to pop fuses.

 

I went through the same thing.
I replaced all the relays, fuses ect.
It was the comp going out that kept causing the problem.
The upgrade kit came with all the parts I already had, and still mounted under the hood.
I found a guy on line that sells viair compressors for lowriders/bagged cars.
He had a great deal on a large chromed viair.
I mounted it under my bed for now, plumbed it into the system, and added a relay to the original Pac trigger/power wire.
Now the pumb runs direct off the battery with no load on the pac system.

I've redone and re-arrainged everything in the original sytem and believe I have it all running off one hose.

Sinse then I haven't had an issue..so far.