PAC Exhaust Brake

[Sailor Fred]

Need some help understanding how my exhaust brake works, if it is working. On my 96 Magna I have a hi and low position on the switch located on the shifter console. Looking at the wiring diagrams this switch controls the brake both in hi and low position. When I operate this switch to low the transmission does not downshift and I do not feel the unit slowing down nor do I hear a change in the exhaust. I do get the PAC brake light on the dash. On the hi side of the switch nothing happens unless the cruise control is turned on in which case the PAC light on the dash comes on but there seems no change in how the rigs comes to a stop and the transmission does not downshift.
Can someone tell me how I should be operating the exhaust brake, does the cruise control need to be turned on? Do I have to be above a certain speed, etc.?
Thanks in advance for any help.

[Peralko]

Fred,
Do you have an exhaust brake or a Jake brake? Normally an exhaust brake does not have hi and low position, but a Jake brake does. The Jake brake will have an on/off switch next to the hi/low position. With the cruise control off, the Jake will work normally. With the cruise on, the transmission will downshift, but the Jake will not come on until you apply the brake pedal.

[Sailor Fred]

There is no on/off next to the hi/low. The drawings call it an exhaust brake as does the paperwork/ manuals that came with the unit.

[CountryFit]

i am using pacbrake. on the selector panel (where there are host of rocker switches. one of them is headlight switch), there is a pacbrake. going down hills, make sure cruise control is OFF, turn the pacbrake rocker switch to on. you will see on dashboard a light came on, and on the selector panel your transmission will show 4. in a moment, you will feel the braking from engine.

if you had cc on and you turn on pacbrake, the gear will drop to 4 but pacbrake will not be activated.

[Duoglide1]

I believe mine to be not correct, but it's possible that yours is the same. If the CC is not set and I take my foot of the throttle quite often the PAC brake does not activate-however if I tap the foot brake even slightly it will activate and stay that way until I depress the throttle slightly.

[deandec]

Originally Posted by Sailor Fred

Can someone tell me how I should be operating the exhaust brake, does the cruise control need to be turned on? Do I have to be above a certain speed, etc.?
Thanks in advance for any help.

My rig is a few numbers older than yours and I have a Cummins engine.

My exhaust brake toggle switch is near the tranny shift pad.

It is either on (lighted green) or off and is a Pac Exhaust Brake.

It will begin a downshift to 2nd gear when the switch is on and the accelerator released. It will do this even if the Cruise Control is on.

It works between 30 mph and 60 mph.

At slow speeds it is difficult to determine if it is engaged.

Some owners did not like the 2nd gear selection so they had it reprogrammed to 4th gear. I suspect that reduces the effect of the downshift process kicking in.

Most of our driving is in the west hills. I leave the brake switch on except when in surface road traffic or level highway cruising.

[Sailor Fred]

First I would like to thank the forum for the help and information in getting my PAC exhaust brake issue figured out.
I talked to Gillig, and Country Coach who confirmed that I had a PAC exhaust brake installed. I obtained a copy of Country Coach schematic #S0395.2. This drawing shows the wiring for the Hi/Low brake system.
The system works like this.
Low
Put console switch on low, switch glows green.
Cruise control must be off.
Transmission does not downshift, not in circuit.
When you remove your foot from the throttle the dash light comes on and the exhaust brake closes. It is real difficult to tell if in fact the brake closed.

High
Put console switch on high, switch glows green.
Cruise control can be either on or off.
When you remove your foot from the throttle, the dash light comes on, the transmission selects 2d gear and starts downshifting until it obtains second gear, and the exhaust brake closes. Once you reach 15 mph the PAC brake turns off.

I cannot tell if the exhaust brake is closing, but in order to test that I need to remove the access cover under the bed.

[deandec]

I tested my pac brake valve by disconnecting the + wire from the brake solenoid and touching the solenoid with a cheater wire from a 12v battery + terminal.

The cylinder jumped and I could see the valve closing.

All done from underneath the rig.

While under there you could lube the pacbrake with the high temp Superlube oil or with the same oil purchased from PacBrake in their bottle. Do this annually. The instructions are on the PacBrake site.