Pacbrake issues

[oldcobia]

My Pacbrake used to work great. Now cycling every 1.5 seconds. Found out when heading for Texas while trying to honk at neighbors. After driving about 20 minutes horn started working again. After troubleshooting I thought the problem was bad pressure switch. Not so. Replaced and same short cycling problem. So now I have to let motor run about 15 minutes before I can thumb my nose at neighbors as we drive away. Any suggestions. Thanks

[wolfe10]

Assume you have the small 12 VDC air compressor-- may be above the rear axle. NOT a good location IMO.

I moved mine to the back driver's side compartment and wired it through a relay so the pressure switch merely closes the relay, vs running all current for the pump through it. Actual voltage to the pump almost a full volt higher.

[CactusTwo]

The new wiring protocol that Brett talked about is Pacbrake Service Bulletin 177, dated August 27, 2005. Available free on the internet or through pacbrake.com. Wire from pressure switch works the activator of the existing relay, minimal wiring.

[oldcobia]

I re-wired compressor as described and all works as should now. Thanks for the inputs. That’s what is so great about this forum. Thanks again

[Trekker01]

My '98 Sahara's Pacbrake compressor seems to run forever, but can't hear it when engine is running, and may be running full time as long as ignition key is on. Is the problem an open air line, so there is no pressure, or a relay issue (if I unplug the power to the relay it quits running) or a faulty pressure switch? I can change the relay easily enough, but have never even laid eyes on the pump or the air lines. If it most likely is the pressure switch, are they readily available? Any ideas?

[oldcobia]

My Pacbrake compressor is used for air horn also. Yours may do the same. I found it was not cycling at all. When turning key on it would run for a second or so then cut off and do the same thing over and over. It was noticed because air horn would not work. I thought it was the pressure switch so I replaced it with one from Pacbrake and rewired it according to bulletin mentioned. Did same thing. Found that small tubing that goes to air tank from compressor was clogged so pressure switch was working correctly. Now with just key on compressor runs about 45 seconds to reach pressure before switch cuts power. If yours runs all the time I would think it will be pressure switch not working or bad air leak. If compressor is building pressure you should be able to tell by hearing difference in sound. Hope this helps some. Don in Tallahassee

[Trekker01]

Thanks, Don. My air horns operate from the same pump. Where is the tank located on your '95 Sahara? I believe you also have the Magnum chassis, only a different engine. Mine is a CAT. The pump would probably run until it destroyed the motor without building up pressure. I seldom use either the pacbrake or the horn. The pacbrake does get used in the mountains, but have not seen any hills in the last 18 month

[oldcobia]

My tank is up front on passenger side under floor. Best access is from ground under bumper in front of tire. Can also see top of tank from access panel in front. Pump on mine is on top of transmission and access is from under bed. Small 1/8 tubing comes from pump to tank. Good luck

[Trekker01]

I have a front entry, and no front hood opening. Tank is not there that I can tell. Very little room with all the dash A/C stuff crammed in the limited space and the Kwikee steps on the passenger side forward of the front wheel.

[CactusTwo]

My '96 Geti has a tank (blue) forward of my front entry Kwikee steps. Easier to get to with the steps out but easy to see when I crawl under on my back. Maybe you should look a bit harder. I also drained "said" tank by removing one of the lowest air lines and there was a bunch of water and rust in it. I have since replumbed lowest connection and put in a T fitting and a petcock drain valve and do the regular maintenance drainage to it.