Pacbrake cutting out

[BKunic]

My Pacbrake has suddenly become very intermittent. NOrmally, while activating it, you hear a "groaning" noise. I assume that this is the small air compressor firing up and turning the butterfly valve. Then after a few seconds the groaning noise stops and it's relatively quiet, unless you step on the accelerator or downshift. If you have the window down you can usually hear a low hissing sound.



For a handful of recent drives, it activated normally, only once the groaning noise went away (as it normally does), it would return for a second or two on it's own - without stepping on the accelerator or shifting gears.



Then today when I threw the switch nothing happened. I kept trying to get the brake to activate, and finally it would on an intermittent basis. Sometimes it does, sometimes it doesn't.



Has anyone had this problem, and if so what did they do to correct it? I looked under the hood and couldn't see anything obviously amiss, such as loose connections, etc.



Thanks in advance,



Bryan

 

[mbaston]

When you say nothing happened, not even the compressor coming on? If the compressor is coming on but the brake not activating, looking at your symptoms, and air line leak comes to mind.

 

[DCaswell]

Sounds like a loose connection where you inserted the pins into the plug on drivers side of engine or a loose electrical connection for the power supply to the comp.

 

[CWoods]

Could be a bad switch maybe?

 

[MPalachuk]

We installed a brake on a customers truck and he came back with the same complaint, We checked it out and found the compressor not running. Trace it back and found no problems, Called pacbrake and they said they have had trouble with the ecm not working right. They had us put a throttle switch in and not use the ecm. They had us do it it under warranty.

 

[jelag]

We install lots of these... ... and we've fixed this problem for other installers... .



90% of the time it is a loose connection where the connections are made to the ECM. There is very little current from the ECM through the wiring harness to the dash switch and to ground. .



We can usually probe the ECM and get the exhaust brake to cycle and we than trace the loose connection and repair it...



In some cases we've had to pull the connector to the ECM and inspect the connections and repair as needed... .



I have our installers actually pull this connection at the time they insert the wires..... making sure this is done right... .



We've never installed the throttle switch and I would assume they would only suggest it as a last ditch effort in that the technican didn't find the bad connection...



Remember that when the cruise control is on and there is a throttle switch in the circuit the exhaust brake switch will have to be turned off... as the throttle pedal comes back to the idle position under cruise control... .



Hope this has been some help... .



Jim

 

[BKunic]

Thanks everyone,



Well, it's working normally now for the most part. I'm off on a run up to Nevada for a few days and will see how it works. If its still acting up when I get back I'll take it to the dealer as they installed it.



Thanks again for the help,



Bryan