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Blizzardking · 05-24-2012, 08:19 PM

Just got the RV back from dealer for maintenance, and exhaust break continuously is blowing fuses. Replace fuse, actuates once and bam, fuse blows. I have never lubed, but I did buy used and I only have owned it 1 year. I located the unit in the engine compartment just to the top of the engine cover, I've read a ton on lubing. I don't have time to order lube oil from PAC... Any ideas or instructions? Thanks...

cod really use that system in the hills of western New York.

JimM68 · 05-25-2012, 12:21 PM

I am not speaking from experience, and gladly bow to anyone who can....

Pacbrakes get hot. So do disk wheel brakes. Perhaps a locally available disk brake part lube would get you by?

Yukon Jack · 05-25-2012, 01:15 PM

Blizzardking,

I have a 2001 Monaco Dynasty with Cummins ISC350 with a PAC brake that is actuated by a foot pedal eletric switch.

I purchased my bottle of PAC brake synthetic lube while shopping at Camping World.

Now to the blown fuse issue. Based on my engine and Coach wiring, I personally would not think it was due to a lack of lube to the PAC brake pivoting mechanism that rotates the butterfly in the exhaust outlet, because the rotating motion is done by an air cylinder that is actuated or controlled by a simple electric-over-air solenoid valve. Even if the actuating arm is stuck in the open position, as long as the PAC Brake solenoid activates, the 12 vdc electric system really doesn't care if the air cylinder moves or not, as long as the sliding solenoid spool plunger is able to fully stroke itself inside the electric coil in the electric-over-air solenoid valve.

My solenoid valve is located on a bulkhead wall, that is just above the rear of the engine, or above the bell housing. Since I do not have a bedroom slide it is mounted to the wall that is actually the framing for the foot of the bed.

There are a few possibilites that come to mind and those would be: 1) Closly investigate the condition of the wiring from the fuse to the solenoid valve to make sure there isn't a short in the wiring somewhere, especially back in the engine compartment where the solenoid is actually located. 2) The other possibility would be a faulty or shorted out solenoid coil in the electric-over-air solenoid valve which would also blow a fuse. 3) Check the wiring at the PAC brake switch or pedal in the drivers compartment to assure that everything looks good in that area.

You can also check the pivoting motion of the PAC Brake rotating arm that is connected to the butterfly on the exhause outlet by firmly grasping the arm and rotate it against the spring tension of the return spring on the assembly. This will at least let you know that the arm can rotate when force is applied by the air cylinder as a result of being activated by the solenoid valve.

Hopefully this will be of some assistance to you in your efforts to find the cause of the fuse blowing.

Yukon Jack

Blizzardking · 05-25-2012, 05:17 PM

Did the best I could as for lubbing, used a high temp lube in the short term. Really couldn't get the shaft to spring open. Disconnected the connector from the solenoid, and checked for corrosion. It appeared clear and secure. Replaced the fuse, and activated the rocker switch for engine break. Took her for a spin, and engine break kicked in, but did not do so again. Replaced the 10amp fuse again, and engine break actuated, slowed me down, and did not come on again. So initial actuation is good, but blows the fuse continuously.

Prior to taking her out and blowing 2 fuses. Randy, from Randy's RV repair was with me, he used a car battery and some other electrical tools, to try and get the PAC to actuate, so as to lube the shaft. Aside from a little smoke from the solenoid, nothing happened. We may have been totally of, as Randy was just trying, as he does not specialize in engines. We rep-plugged connector, and still no change. Once the fuse is replaced, the light on the rocker switch comes on if it's rocked on. Retarder does work initially, but will blow fuse on return.

Hooligan · 05-25-2012, 06:50 PM

The solenoid smoking does not seem to be an encouraging indication.
Here is a wiring diagram, it may apply to your engine and transmission combination..
Pacbrake phone # at bottom of schematic...A call to Pacbrake may help.

Hope this helps.

Blizzardking · 05-25-2012, 08:28 PM

I hate being handcuffed by this. Wish I could replace what needs fixing in a whim. The fact that my Good Sam Extended Warranty didn't cover this, is still an open wound.

Blizzardking · 05-25-2012, 10:21 PM

Thanks, although I don't see a schematic? Ideally I would like to replace any relays involved, and the Solenoid. I'm hoping Cummins or Penn Detroit carries them in stock.

pwhittle · 05-26-2012, 04:04 AM

The relay on my 1994 Monaco is a standard relay available at any auto parts store.

Paul

Papa_Jim · 05-26-2012, 07:17 AM

Tri-Flow lubricant is a recommended choice and available at most hardware and automotive stores.

Smoke coming out of the solenoid indicates that the solenoid has a dead short, which explains the fuses.

The Pacbrake itself. If you grab the arm and it won't move, the Pacbrake is seized. If you liberally spray it down with lubricant and work at it you can get it freed up.

The secret is to lubricate it when you park it, and again before the trip. I keep forgetting to lubricate the Pacbrake when I put the coach into storage, so I have to spend a little time freeing it up when I take the coach out of storage.

Blizzardking · 05-26-2012, 10:54 AM

So your saying try replacing the solenoid? I will try for the Tri lube. I see the relays, I will replace...

Wouldn't it be safe to assume that the relays are fine, if the system powers up each time fuse is replaced?

Mageksl · 05-26-2012, 12:19 PM

Whenever anything electronic is built the manufacturer puts in a certain amount of smoke in the unit. The amount of smoke is generally determined by the amount of voltage/amperage used by the unit. This smoke is absolutely essential to the proper operation of all electronics. Once you let the smoke out they seldom, if ever, work again. Well known fact!

Mr_D · 05-26-2012, 12:35 PM

Quote:

Originally Posted by Blizzardking

I hate being handcuffed by this. Wish I could replace what needs fixing in a whim. The fact that my Good Sam Extended Warranty didn't cover this, is still an open wound.

Another reason not to by a service policy (they're not "Extended Warranties" no matter what they call them), they are a contract, nothing more and only as good as the exclusions as written.

pwhittle · 05-26-2012, 03:26 PM

Blizzard,

I would replace the relay and check the wiring between the rmgbefore I replace the solenoid.

If you have a multimeter you can measure the resistance or the solenoid.

I would expect it to be less than 20 ohms bot more than 3 ohms.

Paul

Blizzardking · 05-29-2012, 05:38 PM

Replaced both break exhaust relays, lubed the PAC, replaced the fuse...Same results: worked perfect the first time, after it was done, fuse blew....;(