PAC Brake PRXB intermittent operation

[bcbender]

Hey all.

Posting a request for a former TDR member and also wondering for my own morbid curiosity. My friend's 05 5.9 3500 has a Pac Brake PRXB ECM controlled exhaust brake that has the enable switch on the shifter (NV5600). He is having issues with it intermittently operating, has told me the the switch wiring checks out and was wondering what to look for next. If anyone has had this issue or similar and found the solution I will pass it along as he plans to use my gooseneck to move his sister this weekend and really wants the exh brake to be reliable.

Coincidently my 04 had the same PRXB and the same problem, but I solved mine with the 20' 6.7....

 

[AH64ID]

Loose connection anywhere?

TPS could not be going to zero.

Relay could be failing.

 

[AEdelheit]

I had a similar problem and it was the pin on the ECM was not fully seated though if he has had it a while then the solenoid or air system is more likely the culprit or the TPS and AH65ID mentioned.

 

[Tuesdak]

I had to oil the solenoid on mine with their special oil several times. It would stick, leak all the system air pressure down, etc. Also some air hoses can leak at the connections enough that the compressor can't keep up.

 

[NLenfert]

This is Nate, bcbender's friend above, I have not been on here in YEARS, Life got busy. All things "check out" I have Air, (New Viar installed to replace 2nd dead PacBrake compressor last month) and it is working and has pressure.
Selenoid works, (when Hot wired, it engages no problem, no sticking) that is only about 1 or two years old, I originally installed my PRXB in 2008 and the original quit after 100K miles and 10 years of use.
Relay works, (tested and also replaced with a new one). Not getting ground from pin from 50 pin connector, (pin 39) I think it is. So, Leaning toward APPS which on my truck means replacing throttle assembly, ($189 from Genos) and the local dealer does not have one nor any dealer in NC is showing one. Or something else is telling the computer not to activate. Or ECM is NG. I leave Tomorrow for Iowa, so I think for this trip I am going to unhook the wires from the ECM and use my Exhaust brake switch wires already run and reroute through the relay so I can engage my PXRB bypassing ECM for this trip, then do more study/order an APPS when I get back after this 2500+ Trip. Thanks for the advice! Looks like I need to re-up my TDR membership... I need to keep this truck another 100K+ miles and probably 10 more years...
Since bcbender gave up on his 3rd gen and went all new tech/stuff on me. Maybe I'll buy his truck in 10 years when he's ready to upgrade again!
Have a good one guys!!!

 

[AEdelheit]

This is Nate, bcbender's friend above, I have not been on here in YEARS, Life got busy. All things "check out" I have Air, (New Viar installed to replace 2nd dead PacBrake compressor last month) and it is working and has pressure.
Selenoid works, (when Hot wired, it engages no problem, no sticking) that is only about 1 or two years old, I originally installed my PRXB in 2008 and the original quit after 100K miles and 10 years of use.
Relay works, (tested and also replaced with a new one). Not getting ground from pin from 50 pin connector, (pin 39) I think it is. So, Leaning toward APPS which on my truck means replacing throttle assembly, ($189 from Genos) and the local dealer does not have one nor any dealer in NC is showing one. Or something else is telling the computer not to activate. Or ECM is NG. I leave Tomorrow for Iowa, so I think for this trip I am going to unhook the wires from the ECM and use my Exhaust brake switch wires already run and reroute through the relay so I can engage my PXRB bypassing ECM for this trip, then do more study/order an APPS when I get back after this 2500+ Trip. Thanks for the advice! Looks like I need to re-up my TDR membership... I need to keep this truck another 100K+ miles and probably 10 more years...
Since bcbender gave up on his 3rd gen and went all new tech/stuff on me. Maybe I'll buy his truck in 10 years when he's ready to upgrade again!
Have a good one guys!!!

If you have an OBD code reader with live data it will show the APPS position, best of luck!

 

[Ozymandias]

Loose connection anywhere?

TPS could not be going to zero.

Relay could be failing.

I think the same, TPS not going to Zero.

 

[AEdelheit]

I remembered seeing a service bulletin from Pac Brake a while back, not sure if this will help or not
http://pacbrakeoem.com/wp-content/uploads/L6120.pdf