Exhaust Brake Wiring / Troubleshooting

[Larry and Heidi Lee]

A few months ago I noticed my exhaust brake stopped working so today I am troubleshooting the problem. The EXhaust brake relay is not receiving the 12v signal to send power to the EBrake solenoid. The relay has a good ground and 12vdc on the ignition side. If I manually apply 12vdc to the relay it clicks and the exhaust brake engages. No power signal comes to either of the EBrake relay terminals whatsoever. I found two leads leaving the EBrake console switch, when the switch is turned ON 12vdc leaves on this wire , when the switch is turned off 6. 45 vdc leaves the other wire. The 12vdc wire goes up into the dash while the other I don't know yet. Hundreds of zip tied wires makes it really difficult to trace. Does anyone have a comprehensive schematic or know of an in line fuse? I'm running out of ideas...

[Gerald Farris]

Larry,
Could you please give the year and model of your coach, or better than that, include it in your signature line for all future references.

Gerald

[Joel Ashley]

Larry, I am emailing you a copy of my EB schematic.  We probably don't have the same coach model/year, but it may offer some insight.

Joel

[Larry and Heidi Lee]

Hi Gerald, I have an 05 Monterey Bayview 4 400 Cat. Strange on the way to an RV park this afternoon the EBrake is working again. I am starting to suspect I have a poor connection at those large 30 pin or so connectors. I think I'm going to cut the connectors out completely and solder those leads together. Any reason you can think of why I shouldn't do that? Two of the four large connectors are badly corroded. The only reason I can think of for these twist connectors was for the assembly of the coach at the manufacturing plant.

Thanks Joel for the schematics, this gives me an understanding of how everything functions together.  

[Edward Buker]

Larry,

I believe those connectors are high quality Amphenol gold plated pin connectors. They were on my last coach if they did not change that. If they are the gold pin type they should be recoverable. The use of having that connector is that they are numbered and good schematics wil have the pin number To wire ID so that you can break a circuit and get a measurement at the pin for diagnosing problems.

You should consider cleaning them with Corrosion X and a tooth brush or whatever smaller brush that will give you access. Leave a good layer of Corrosion X in place when you are done. If you do that you should not get corrosion again. If you are getting water leakage in that area you need to find the source and seal it. If you do go ahead with the solder job there are versions of heat shrink tubing that have a sealant activated by the heat that will seal that connection so that moisture cannot penetrate it. Marine and some auto supply houses should carry that product.

I'm just giving my perspective here.  Gerald I'm sure will chime in with his excellent advice when he gets a chance.

Later Ed  

[Joel Ashley]

The windshield's rubber gasket on my coach deteriorated badly at the top.  I suspect it is the source of the water that ends up pooled on my electric bay's floor after a hard rain.  After a post by Ed last year, I applied Corrosion-X to all exposed metal in there.  I cut the cable ties binding the heavy cylindrical connectors so I could get them apart, and found 1 or 2 corroded pin ports, which I cleaned.  I used "bulb grease", aka dielectric silicone lube, on the pins as an antioxidant to fight corrosion.  I guess Corrosion-X would work there too.

Soldering all those wires would be a far bigger task.  Stop the incoming water and mitigate the corrosion instead.

Joel

[Gerald Farris]

Larry,
Ed is right in that if the connector is repairable (clean and seal the corrosion while still maintaining good contacts) you would be better off repairing it instead of replacing it. However I do not think that Monaco used gold pin connectors, and if the corrosion is bad enough, the terminals will be corroded to the point that they will loose the spring tension in the connector because they will be to thin. This loss of spring tension in the terminals will not allow them to establish and maintain a proper connection. If this happens, you have no choice but to replace or eliminate the connector.

In the automotive business we would normally replace the connector with a new connector because this makes a neater repair and keeps the vehicle in original condition for future maintenance. However, the connector will be expensive and hard to find. So if you are careful in making sure that you solider the correct wires together, this approach is very acceptable as long as you understand that it will possibly make troubleshooting the circuit more difficult in the future.

Gerald  

[Dennis Mecklenburg]

Larry,
I had a similar PacBrake problem, did similar troubleshooting that you have done, replaced the relay and all problems were solved. Have you eliminated the relay as the real culprit ?? If so, good luck in your search !
Dennis M

[Larry and Heidi Lee]

Thanks for everybody's input. I just had the windshield replaced with a new gasket, all my marker assemblies replaced and sealed so I'm hoping that will resolve the incoming moisture to other electrical bay. My connectors don't appear to have any gold but Ill try the corrosion preventative first. I need to do some more testing but the EBrake is working again. I'm wondering if I am suffering from some brain fade and just assumed it wasn't working on the last trip. Then while testing I didn't have the engine up at the correct rpm so the ecu never triggered the relay. Duh! Not sure what I'll do about those connectors but at some point I think they need to be replaced.