Author Topic: Pacbrake exhaust brake need relay location  (Read 2941 times)

Bryan Beamon

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Pacbrake exhaust brake need relay location
« on: December 13, 2024, 08:13:25 PM »
Our exhaust brake is not working on our Cat C9 400hp.  In trouble shooting with Pacbrake they seem to think the solenoid is not getting the signal to activate the Pacbrake. Having difficulty locating the relay. I found the solenoid and found the ground wire but tracing the second wire to the relay has me stumped
C & Bryan Beamon
2006  to present
2007 Contessa 42ft Cat C-9 400hp
1996 to 2006 97 Beaver Patriot Camden

Eric Maclean Co-Admin

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Re: Pacbrake exhaust brake need relay location
« Reply #1 on: December 13, 2024, 11:46:03 PM »
Bryan
On page #2 of the 2007 contessa wiring diagram found in coach assist library shows relay R18 as the exhaust brake relay.

It is to be noted that the exhaust brake is controlled through the engine ECM ( engine control module ) in conjunction with the TCM ( Transmission control module )
The exhaust brake relay ties into the brake light relay so the brake lights activate during exhaust brake operation.
If a following car can see brake lights under exhaust brake conditions the ECM is sending a signal to activate the exhaust brake.

Hope this helps
Eric
1997 Patriot Yorktown
3126-B
2009 Chevy HHR
Roadmaster falcon tow bar
Demco Air Force one tow brake.

Bryan Beamon

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Re: Pacbrake exhaust brake need relay location
« Reply #2 on: December 14, 2024, 12:33:55 AM »
Eric, thank you. Do the Attached photos designate the relay you describe? I was confused by the description on the relay in my front service bay saying exhaust brake sol.
C & Bryan Beamon
2006  to present
2007 Contessa 42ft Cat C-9 400hp
1996 to 2006 97 Beaver Patriot Camden

Bryan Beamon

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Re: Pacbrake exhaust brake need relay location
« Reply #3 on: December 14, 2024, 12:34:59 AM »
Second photo
C & Bryan Beamon
2006  to present
2007 Contessa 42ft Cat C-9 400hp
1996 to 2006 97 Beaver Patriot Camden

Eric Maclean Co-Admin

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Re: Pacbrake exhaust brake need relay location
« Reply #4 on: December 14, 2024, 12:41:38 AM »
Bryan
Yes the relay is labeled exhaust brake solenoid: because it sends the signal to the air solenoid that operates the exhaust brake.

Eric
1997 Patriot Yorktown
3126-B
2009 Chevy HHR
Roadmaster falcon tow bar
Demco Air Force one tow brake.
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Joel Ashley

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Re: Pacbrake exhaust brake need relay location
« Reply #5 on: December 14, 2024, 01:27:12 AM »
As you know, the C9 uses a "Pacbrake" instead of the internal compression brake used on larger models.  It's commonly on our rigs made by Jacob's Systems, but is for all intents a twin of the original Pacbrake.  Before I'd get into the electrics, I'd check the cylinder operation and whether the butterfly flapper moves freely;  they often seize from lack of regular lubrication.  Also see that airlines aren't leaking and the solenoid hasn't corroded up, or wires failed there where heat and exposure is greatest;  kudos for having already found the solenoid.  I keep a bottle of lube and try to remember to apply it every so often as prescribed, usually at least prior to or after "storage" periods.  I believe there may be a guide to lubing in the brake section of Coach Assist.  Also of course is the common oops of having both the exhaust brake and cruise control switches on at the same time.

Joel

https://www.youtube.com/watch?v=9QxZhk_CUB8

https://pacbrake.com/superlube-exhaust-brake-lubricant.html?gad_source=1&gbraid=0AAAAAqs6Wyd1ZS1QKcilDLjT_0gFaYVF_&gclid=Cj0KCQiA0--6BhCBARIsADYqyL9m0bmU9wRLim4-GVW24NKT144Bm4EihrDLjNyF_Q8iZgioHog-F4saAkm-EALw_wcB
Joel and Lee Rae Ashley
Clackamas, Oregon
36.9 ft. 2006 Monterey Ventura IV, aka"Monty Rae"
C9 400HP Cat
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Steve Huber

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Re: Pacbrake exhaust brake need relay location
« Reply #6 on: December 14, 2024, 04:27:21 PM »
Joel,
On the 07 the exhaust brake works with the CC on. Makes driving a bit more convenient. Only downside is that with the exhaust brake on the power steering will sometimes "buck" at slow speeds as noted in previous threads.
Steve

Bryan,
If you haven't, suggest you print pgs 2 & 4-7 of the 07 Contessa wiring diagrams (relay & fuse location and fuse ID info). Put them in plastic sheet protectors and leave them in  the forward electrical bay. (I taped pg 2 to the inside of the bay door). Saves a lot of hassle when you need to check on a fuse or relay.
Steve
« Last Edit: December 14, 2024, 04:33:04 PM by Steve Huber Co-Admin »
Steve
Coachless
2015- 6/24  07 Contessa Bayshore C9,  400 hp
2013-2015: 00 Marquis Tourmaline, C12, 425 hp
2005-2013: 01 Contessa Naples, 3126B, 330 hp
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