6.7 exhaust brake switch

[Thatonetruckguy]

Just curious if anyone has taken and wired their own switch in for the factory exhaust brake on the stick .Im currently looking into this as my truck is a stickshift.I do a lot of towing through the winding mountain roads up here in Washington.I think it would be nice to have a convenient switch to hit (mounted to the shifter ,instead of beating the dashboard every time I'd like to turn it off or just feathering the throttle to keep it from engaging . If you have done your own switch how did it work , was it much better than the factory spot? Anyway , all info is appreciated!

 

[n7gxz]

You can not just wire a switch in to the factor switch. All of the "switches" in the new truck are nothing more then a computer keyboard key as they just feed into the CanBus system that the computer reads. You maybe able to go directly to the E-brake but I'm not sure how the computer interacts with it.

Kevin

 

[EDankievitch]

Any one of the computer geeks here figure out how to get the Engine break to stay on the setting you like to use it on so you don't have to turn it on at every start up?

 

[Thatonetruckguy]

I understand the factory method is nothing more than a momentary reference signal that tells the ecm to turn it on . I was just wondering if you could mount a similar momentary switch to say the stick and how well it would work , or if it has for anyone else .

 

[jelag]

I'm a retired PacBrake distributor and our shop installed lots of PacBrakes over the years and I've sold many members of the TDR those units.... ON those units there were two connections at the ECM.... one connected to the switch.... and the other side of the switch went to ground... all the switch was... was a connection to ground that signaled the computer that the operator wanted the exhaust brake to come on.... and when the rest of of the conditions were met... the ECM grounded a second connection to close the relay to run the exhaust brake.... I assume that the connection was a path from the ground side of the relay, through the ECM to the switch and than to ground.... hope you follow the logic here...

I've been retired long enough that I don't remember the two pin #'s... I'm guessing that if you pull the dash open you'll find 2 wires going to the switch... some are lighted and require a 3rd wire to light the switch.... since the dash switch is a momentary contact switch.... its locking a relay, again I assume in the ECM.... I'd disconnect the wires from the dash and see if I wired in a momentary switch, that the exhaust brake circuit would function.... I'd than relocate that switch to the shiftier... I would also assume that a wiring diagram would provide the correct information.... A note here... the pin connections on the ECM require you to remove a plug and push in the connector... HOWEVER it requires a special tool to REMOVE that same pin once its locked into place so I suggest you not work at the connector at the ECM..

PacBrake offers several switch housings that use a common switch... the difference of course is the center hole that mounts to the shiftier based on the diameter of the shiftier.... I like you.... live in WA and love the shiftier switch... however my new ride is a automatic and I'm going to use the factory system..

 

[n7gxz]

Jim, This is not the case with the newer CanBus systems. The E-brake switch on the dash is part of a PC board that converts the switch being pushed to a CanBus signal that goes out over a twisted pair of wires that is used for CanBus communications. I don't know if the E-brake also uses the CanBus or if the ECM is actually switching the 12V power to it. My guess is that the E-brake is using the CanBus and has it's own internal computer.

Kevin

 

[Thatonetruckguy]

Well even if it is CanBus ,I bet there has to be a way to mimic that signal the computer wants to see through a different switch.CanBus works like SAE J1939 correct ? or is very similar ? I Read Carbonite Cummins article on how to wire the relay in for auto on ,and he noted the use of a resistor.So if you had a double throw momentary switch with the correct resistors in place you should be able to mimic the dash switch output messages,one would think .

Brenden

 

[jelag]

Kevin....

Thanks for the update.. I had no idea how this new system worked but knew a lot about the 5.9's... I'm wondering if someone has the wiring diagram to verify that the buss does control the brake... or if the switch goes directly to the ECM...

 

[pcarlson]

So you want a separate switch, it should be easy enough to wire a momentary switch in place of the factory one. I believe it is just a 5v signal wire to the computer. Shouldn't be any CANBUS twisted pairs at the switch itself. The computer should sense the voltage and turn it on and off.

 

[pcarlson]

Any one of the computer geeks here figure out how to get the Engine break to stay on the setting you like to use it on so you don't have to turn it on at every start up?

This works through 2009 for sure.




Here what you'll need to have an Automatic EB Switch:



1 relay with SPDT ( Single Pole Double Throw )

1 resistance 15 ohms

16 ga wire

1/4'' female straight connector with plastic isolator ( to connect on the relay )

16 ga TAP connector ( the blue ones )


Here's the way to do it:


1. Tap 1 piece of wire from the PINK/Yellow wire on the cigar lighter to pin 85 on the relay

2. Tap 1 piece of wire from the Black/Yellow wire on the cigar lighter to pin 86 on the relay

3. Tap 1 piece of wire from the Violet/Brown wire from the EB switch to pin 30 on the relay

4. Tap 1 piece of wire from the Brown/Orange wire and connect the other end of the wire to the 15 Ohm resistor

5. Connect the other end of the resistor to pin 87a on the relay


This won't turn on with remote start and the switch still functions turning it off and back on.

 

[n7gxz]

pcarlson,

That will not work on my 2011. I have the dash apart and the EB switch is part of a PC board (hard soldered to) along with any other switches in that bank. There is a just 1 connector on the PC board that is a connection into the CanBus.

Kevin

 

[jdross440]

On my 2007.5 instead of wiring with a relay I ran a wire out to starter solenoid wire. I put the resister and a 1amp diode inline. At the starter wire I put a 2 amp fuse.

 

[pcarlson]

pcarlson,

That will not work on my 2011. I have the dash apart and the EB switch is part of a PC board (hard soldered to) along with any other switches in that bank. There is a just 1 connector on the PC board that is a connection into the CanBus.

Kevin

Thanks for clarifying the change. I would suspect your description is valid for 2010 and up. Shame there isn't a simple fix.

 

[Flopster843]

You'll have to figure out what the switch is doing when you press it internally and mimic that externally between the two wires. The purpose of the resistor in the older trucks is to get a proper CANBUS signal sent through the wiring. If you can acquire the wiring schematics for a 4th gen, you should be able to measure the circuit through the switch and duplicate that reading with a resistor. Wire a momentary switch with that resistor inline with the OEM wiring and see if it works.