Exhaust brake shutdown,

[Christopher Clark]

2002 Monterey 350 ISC Cummings, exhaust brake functioned fine for 200 miles. Traveled some bad surface roads and it stopped? Dash lights comes on Exhaust Brake, but no activation when you let off throttle. No secondary light indicating brake is active.

[Joel Ashley]

The butterfly may be seized up.  They need at least annual lubrication with “PAC-Brake” oil.  http://blacksmokeindustries.shopgate.com/item/39333030?gclid=EAIaIQobChMIhsal6dnF3AIVhMDACh365woKEAQYASABEgJ8NvD_BwE

You can see the unit via the bedroom/wardrobe engine access portal, engine top street side in the exhaust tube, although your Cummins may be somewhat different than my CAT.  It may take some doing to free the valve and lube it and it’s linkage.  There is also the possibility there is a vacuum or electrical issue... follow the lines from the air cylinder/rod and have someone flip the exhaust brake switch while you watch the device operation and see if the solenoid at least tries to activate the air cylinder.

For reference consult here:  http://pacbrakeoem.com/wp-content/uploads/L5300.pdf
Yours like mine may be made by Jacob’s rather than by PacBrake, but the principles are the same.

If the butterfly is freely moving and the solenoid electric isn’t getting 12v, there are other electric components suspect, such as relay(s), fuses, or circuit breakers probably in the electrical bay, street side frontmost.

Joel

[Christopher Clark]

Joel, thanks for the info. I pulled the air cylinder off of the valve on the PacBrake and found that the valve moves freely. I don’t think the valve is the problem. I found the relay in the front street side compartment labeled “Endurance Brake”. I tried to test for power at the relay while my wife operated the switch from the operators position. I found no power, not sure if the way I’m testing is correct? Would the coach have to be in motion? I tested while in neutral. Also attempted to test after reduction in rpms. No power at relay found? I’m going to replace relay just because it will be easy, if it doesn’t change issue I’ll have a spare.
 Can anyone else think of what to look for to cure a non functioning exhaust brake??

[Roy C Tyler]

Check for corrosion on the spade terminals of the switch in the console. I had an intermittent problem when I first bought mine in 2013 and cleaning the connections fixed it.

[Christopher Clark]

Ok thanks I’ll check the the switch connections. Does anyone know if there is supposed to be power to the relay while the coach is parked in neutral with the engine running?

[Gerald Farris]

Christopher,
Since you did not say what the manufacturer of your exhaust brake is, I am assuming that you have a Pac Brake, and if so this should be your wiring diagram.
http://pacbrakeoem.com/wp-content/uploads/L5206.pdf

Gerald 

[Christopher Clark]

Gerald it is a PAC brake, thanks. Looking at the diagram it appears I should have power to the relay while the engine is running, reguardless if I’m in neutral or not. Need to resolve no power issue.

[Joel Ashley]

At the risk of being over my head with anything beyond the valve itself, I should proffer here that the tranny is involved with the exhaust brake operation.  The Exh Brk relay (K9 on mine) is fed from the shifter panel circuit breaker that's on the Ignition On side of the circuit breaker tree.  It's likely that indeed your tranny needs to be in gear for the shifter panel to pass power to the relay.

If there's still no power at the relay even then, perhaps the left driver's sideboard needs to be disassembled for access to the underside of the shifter panel so you can check the connectors, or it may lift out easily enough.  It's sort of a "mightaswell" since you may be there checking Chuck's suggestion anyway.  Also on mine there are two other relays coming off the engine ECM, one for the Smartwheel and one for the brake lights, that feed into port 85 on that Exh Brk relay.  Now it gets too complex for my wherewithal.  Perhaps Gerald's diagram input will help.

I'd just go crank my rig up and verify some things for you, but it's shut down for storage.  And your model is dissimilar to some degree.

Joel

[Christopher Clark]

Thanks to all that have responded! I apologize for not closing this out sooner. My exhaust brake is now currently functional. Not entirely sure what cured it. I found 4 related relays, tested each one, all working. Found 1 of the large multi pin sockets in the front compartment with a recessed and corroded pin, cleaned and corrected. I removed 4 butt connectors located near the exhaust brake solenoid and replaced with 2, after shortening  some excessive wire leading to the solenoid. Wished I knew for sure what cured it. I have made 2 more legs of our journey since repair, approximately 500 miles, working fine.
Can anyone tell me what is the Endurance brake vrs Exhaust brake?  I’m assuming the Endurance brake is part of the Allison transmission as it interacts with the exhaust brake function?

[Mike Shumack]

Can anyone tell me what is the Endurance brake vrs Exhaust brake?  I’m assuming the Endurance brake is part of the Allison transmission as it interacts with the exhaust brake function?

Just different names for the same thing, I think.  https://www.wabco-auto.com/en/products/category-type/foundation-brakes/endurance-brakes/

[Joel Ashley]

Those pin socket issues can sneak up on you because the strapped-down cylinders are hard to get into and hide the problem, and are your likely culprit.  I went through all of mine in the “electrical bay” a few years ago after reading a thread here, and saw a number of burgeoning green pins/sockets that I cleaned and used bulb or dielectric grease on.  The hassles are that you have to snip and later replace a lot of wire ties to get at the couplers adequately, and even then they don’t always come apart readily.   

I have a bulb and socket cleaning kit, but there may be ones available for smaller connectors like these that are sized more appropriately.  The use of a desiccant or rechargeable dehydrator in that bay is also a good idea to fight corrosion.  And sprays of Corrosion-X on exposed metal and connectors in there helps.

Joel

[Dave Atherton]

Good Morning Gentleman,
Driving with exhaust brake on or engaged so that every time you let up on foot accelerator the exhaust brake will engage can lead to problems and is not recommended. One reason is that the moving parts and electronics needed to down shift will cycle only so many times before wear begins to take its toll. They were not designed for constant usage. The more important concern is the restriction of hot exhaust gas in the engine. Retaining heat inside engine valve train is not recommended. This topic has been “around the yard” several times. The driver is in control how he or she operates the motorhome. Driving with it on is convenient it but can cause engine problems and expensive repair bills ahead.
Ask Dave,  Dave Atherton Retired Cat Mechanic

[Stan Simpson]

I'm guilty of having the exhaust brake on all the time. So, what do you suggest Dave?

1. Turn it on each time? If so, when?
2. Don't use it all the time, only in steep downhill conditions?
3. Other ideas?

[George Harwell]

I never drive with the switch on. Too much jerking back and forth. I turn the PAC Brake switch on as needed and then off when braking is complete. Has worked well for me for 15 years.

[Dave Atherton]

Stan, the exhaust brake works well on long grades and downshift of transmission. The engine exhaust pressure will over take the valve and keep it open until you get down to speeds 45 mph or less. My
suggestion is to make you aware of the downside of constant usage it was not meant to do. There
has been many pro and cons on this subject and it is not my area to tell you how to handle your motorhome. I would contact the builder of your brand exhaust brake. I do have information from
the company that makes compression brakes for sleeved engines and they also market the exhaust
brake also called jake brake. The owners manual spell out correct usage for there product of which
I have. Dave Atherton a Retired Cat Mechanic