Pac Brake Pedal

[mexicanpilot]

I recently starting having problems with the pac brake not engaging on our 1998 Monaco Dynasty. I would tap the pedal a lot and then it would start again. I decided to clean the pedal and then it started working perfectly for several weeks until it totally failed. I called Monaco tech and he said 98% of all pac brake problems are a bad pedal. ($80 + shipping) He also indicated, as a short term solution, to get home, that if I got a simple on off toggle switch and wired it with the two wires going to the Pac Brake pedal, it should work. I tried that, disconnecting the pedal but it did not activate the system and downshift the transmission. I've checked the two wires and they had 12 volts going to both sides, also checked the 10 amp engine brake fuse, which was ok. Also did a continuity check and both wires from the fuse box seem in tact. (Although when the toggle switch was off, I got a slight buzzing sound on the circuit. Not sure what that means, kind of a warbling tone) Then I called Pac Brake and their tech said that if I wired two wires back to the engine compartment to the Pac Brake solenoid, and then connected them, the brake would function. I am out of my element at this time, didn't see any electrical wires near the pac brake cyliner and don't want to experiment and will take the unit in to have it checked out. Pac Brake says some manufacturers put an in-line solenoid on the way back and he didn't know what this Monaco Dynasty had. Just FYI. I see in some posts that many don't care for the Pac Brake, but I'll tell you, in driving home, just having to manually gear down the transmission in lower gears, the pac brake makes a huge difference. I just had freightliner check my brakes and after 91,000 miles, I have 75% brake show life remaining! mexicanpilot

[jacwjames]

My PacBrake does have a solenoid valve in the air circuit that controls the brake. If you flow the air line it will lead you to it. Don't know how that interacts to with the transmission though.

I have a rocker type switch on my drivers console that controls the PacBrake, the way the console is configured I can lay my hand down and know where the switch is without even looking.

Agree on the performance of the PacBrake, it really does help. We live in East Tennessee and pretty much any way we go we have to cross some sort of mountain.

[jelag]

I was a pacbrake distributor for almost 20 years and we sold, installed and serviced them... in most circuits (not all) the pedal completes a ground circuit that turns on an air solenoid that turns on/off the brake... and the toggle switch suggested above would correct this.. if the foot pedal is bad... however in a lot of the cases the solenoid is either bad, or contaminated with dirt... some of the solenoids can be serviced by taking it apart, cleaning it and putting it back together... the coil can be tested with an ohm meter.. when power is applied to the solenoid it should turn on and apply air to the air cylinder... If you can't see how to service the solenoid than replace it... there are lots of air solenoids that will work... look to PacBrake, Amazon, Ebay, your local PacBrake distributor for help/parts...

In almost all cases with mechanical fuel systems... there is also a switch on the fuel pump if the vehicle has a mechanical throttle linkage... when the throttle is released and the linkage returns to idle, the linkage touches a switch and closes a circuit so the PacBrake will engage... How this works.. is that this switch is usually in SERIES with the foot pedal... so that both switches need to be closed for the PacBrake to engage...

Also on older brakes that are not NITRATE COATED... they can sometimes rust up and the butterfly will not move because of the rust... in this case you can supply air to the cylinder and the butterfly will not move... when the housing is rusted it must be disassembled and cleaned... DO NOT remove the butterfly from the SHAFT... this has to be factory set so that when the brake heats up, it will still work... OIL OR GREASE will not lubricate this once the housing has been removed from the engine... you must free this up with solvent... completely dry it off.. and lubricate it with a special silicon compound that will with stand the heat... common oil or grease, even EP synthetic grease will still fail at 500*F... I've never found anything but the silicon based material that works...

And the last comment is to always use the brake... always... even in town to prevent moisture from cold engine warm up generate the moisture/rust..

Hope this helps... of course there are other reasons why this might not work.. but I've covered the most common...