Exhaust brake function in FL Chassis

[Zapper58]

I want to disconnect the exhaust brake switch function from the transmission and the brake light controls.I want the brake to function but not to downshift the transmission and turn on the brake lights. Suggestions on which way to go ?
Thanks, Jim

[palehorse89]

Originally Posted by Zapper58

I want to disconnect the exhaust brake switch function from the transmission and the brake light controls.I want the brake to function but not to downshift the transmission and turn on the brake lights. Suggestions on which way to go ?
Thanks, Jim

1. Downshift- Go to a Allison Authorized Service center, they will have to re-program the Transmission control module, you can select what ever gear you want.....1-6. 6th will give you no downshift but the Allison will still follow its rpm/speed gear select.
2. Brake light, is it just your 3rd light that comes on?
Mine is a Spartan chassis, in the rear fuse box there was a "Diode", fuse style, removed it. No 3rd brake light when using engine brake to "Maintain" speed.
Maybe a call to Freightliner or a member with the same chassis can help??

[Zapper58]

So will it let me turn on the brake switch in 5th , I can downshift to 4th and it will stay in 4th till I downshift again ?

[palehorse89]

Originally Posted by Zapper58

So will it let me turn on the brake switch in 5th , I can downshift to 4th and it will stay in 4th till I downshift again ?

My brake switch is on all the time since the re-program........If needed, I use the shifter pad to downshift(To raise the RPM's)........or the Allison will do it itself per the RPM/speed parameters programed in it.
The engine and transmission controls won't let you hurt them.........they are protected so to say by the Transmission control module and the Engine control module.

[gatorcq]

I really do not understand this:
".I want the brake to function but not to downshift the transmission and turn on the brake lights"

Brake comes on Lights Must Come by DOT. You slow down and the Transmission will downshift, like ALL transmission.

So maybe he needs to be very specific as to what he wants?

Engine and transmission computer work together to keep drivers from damaging of destroying the engine.

Brake lights some on because the brake comes on. Requirement.

[gatorcq]

Sorry, one more item:
maybe you should ask and learn about Latch/Unlatch mode for transmission with Exhaust Brake and NOT a Jake-Brake

[palehorse89]

Originally Posted by gatorcq

Sorry, one more item:
maybe you should ask and learn about Latch/Unlatch mode for transmission with Exhaust Brake and NOT a Jake-Brake

I believe the "Latch/unlatch " is specific to CAT.......not Cummins.

[Pigman1]

Originally Posted by gatorcq

I really do not understand this:
".I want the brake to function but not to downshift the transmission and turn on the brake lights"

Brake comes on Lights Must Come by DOT. You slow down and the Transmission will downshift, like ALL transmission.

So maybe he needs to be very specific as to what he wants?

Engine and transmission computer work together to keep drivers from damaging of destroying the engine.

Brake lights some on because the brake comes on. Requirement.

The above statement is not correct. The Federal Motor Vehicle Safety Standards give the manufacturer the option to either turn on or leave off the brake lights when the exhaust brake is activated.

If the OP was wanting the brake lights to be OFF when the exhaust brake activated, I'd seriously reconsider that position. We've had 2 Freightliner chassis Class A's that when the exhaust brake activated the brake lights came on. We found those coming up behind us on a long downhill would know we were retarding our speed. When we got our 2013 Tiffin on a Powerglide chassis, the brake lights would NOT come on when the exhaust brake (compression brake) was activated. A trip to Alaska showed this was not a good idea as we had vehicles coming up behind us at a high overtake on numerous long downgrades until they were close enough to see their excessive overtake speed.

Upon our return I asked Tiffin to reprogram the system so the brake lights would come on under these circumstances. THey tried but could not because of the way the dash was wired. Later years of the Powerglide did have the necessary systems so the brake lights came on when descending or slowing under an exhaust brake.

[Gordon Dewald]

Not sure why anyone would not want to warn others that the unit was braking. Stealth mode for insurance claims perhaps!

[palehorse89]

Originally Posted by Gordon Dewald

Not sure why anyone would not want to warn others that the unit was braking. Stealth mode for insurance claims perhaps!

What if one is, using the engine brake, was not slowing, going down a long hill on the interstate, possibly picking up speed, even with the engine brake on............hits the brake pedal, brake lights come on, then off when the pedal is released, or maybe never had to press the brake pedal, due to the engine brake was being used while on cruise control to "Maintain" a set speed.
The semi's that we all follow work this way..........no brake lights when using the engine brake......
Years back, my when using the engine brake, it would activate the trailer brakes.........
In discussions on this years back, some class 8 trucks also had this brake light feature it was found, but not many.
I have come to believe it is just a RV thing........

Merry Christmas Gordon!!!!!!!!!

[Zapper58]

Well thanks for all the responses, lots of onfo. As far as the switch disconnect from transmission; would enable the exhaust brake on the engine to turn on regardless of what the transmission gear is in . The position of the accelerator will determine when the brake turns on. trans would or could be shifted down without the exhaust brake switch telling it to downshift. I would rather have the capability to turn on the flashers when going downhill with the brake on. I can drive diesel pickup this way 25-35 mph downhill , exhaust brake on , flashers on .

[palehorse89]

Originally Posted by Zapper58

Well thanks for all the responses, lots of onfo. As far as the switch disconnect from transmission; would enable the exhaust brake on the engine to turn on regardless of what the transmission gear is in . The position of the accelerator will determine when the brake turns on. trans would or could be shifted down without the exhaust brake switch telling it to downshift. I would rather have the capability to turn on the flashers when going downhill with the brake on. I can drive diesel pickup this way 25-35 mph downhill , exhaust brake on , flashers on .

I am not following what you are asking here..........

[Algoma]

Now even I am confused. The OP has an exhaust brake, not an engine brake. You can get your Allison shop to program the transmission to pre-select any gear or non at all when you throw the exhaust brake switch. If you are traveling at 60mph and have the pre-selector set to 2 (which seems to be the default) nothing will happen when you throw the switch because the rpm's are too high. On my previous coach (with exhaust brake) I had mine programmed to 4 because I found that it was capable of maintaining my downhill speed without dropping to a lower gear. As far as the brake light is concerned, I have no idea if it was on or not. But as I never got rear-ended by a semi I assume it was on.
My new coach has a 2 position engine brake and is programmed to select 2 when it is activated. On the low setting it easily slows me down on a 7% incline and the high setting nearly throws me through the windshield so I never use that option.

[Zapper58]

switch on ,foot off acceleration pedal (Depending on the vehicle speed), trans down shifts.