2nd Gen Non-Engine/Transmission wiring for Jake (brand) brake

[monkfarm]

I installed a BD switch on the gearshift for the Jakebrake. In the stock switch, I discovered 2 hot wires, and 2 grounds. I decided one hot was just to power the light inside the switch, so I used just one hot, and one ground to power my new BD switch.

The (Jake) brake was much faster (instant), but I'm wondering if I'm hurting anything by this wiring? The old Cummins jake switch (rocker ) lead to about a 3 or 4 second delay in the brake coming on.

I do get a little black smoke when I start to accelerate after using it, and there is no power on the engine when it is on, the butterfly won't pop back like it did before with the old switch.

Any response on this?? Maybe there is something in the archives? It sure seems to work better now, and much more usable because it is instant.

 

[dresslered]

It's been awhile since my installation, but it sounds like you are not connected to the ECM any more? The circuit should actually be the two switches in series (one being the ECM and the other being the BD switch). Each would have the ability of turning off the Jacob's. Having the ECM in the circuit will guarantee that you do not drive with the Jacobs on. Also, 3-4 second delay sounds a bit long. Mine takes about 1-1/2 seconds which is nice because it allows shifting without the Jacob's engaging. I vote for keeping the delay.



P. S. A VERY slow reacting Jacob's could possibly be a small leak in the vacuum circuit.

 

[monkfarm]

Thank you so much for your quick reply!!

I forget how the 2 hots came together, I will have to look again at the switch, but I'm sure it is just 1 switch? I'd better look at it again before I spout off. But (about your ps) any idea about where the leak would be on the vacuum?? Again, I'll have to take a carefull looksee. Thanks, I will check for leaks. And the ECM should be in there, well interesting, makes sense! Thank You Sir!!

 

[dresslered]

Let me try to decipher the notes that I made several years ago. I actually use the ECM, the Jacob's toggle switch (as a master), and a Napa shifter mounted switch. However, you can disregard the Jacob's switch if you wish. You are correct that one of the power and ground connections are solely used for the toggle switch illumination. It is the other two that you should focus on:



Referring to the original Jacob's wiring harness, you should have a red wire coming from the ECM (pin 20). It then enters the toggle switch harness as a black wire. The black wire should then have a 10-amp inline fuse attached. You want to connect your BD switch in series with this black wire if you choose to retain your toggle switch as a master as I do, otherwise, you will want to connect the other side of your switch to the yellow wire (which ultimately goes to the vacuum solenoid).



Here's how the circuit works. The ECM supplies the delayed (no throttle condition) 12V @ 0. 83 amp source. Depending on whether your switch is on or not (and the master toggle if used is also on or not) will determine whether the vacuum solenoid gets activated.



Regarding the vacuum leaks, the easiest way is to hook up a vacuum gauge. I've accidentally knocked the vacuum lines loose so many times while working in the engine compartment, I even added a dedicated gauge. The vacuum also is used for all the HVAC controls as well so there are a number of places in which you can have a leak. My truck rides at a constant 25-26 in. Hg if that is any help.



Have fun Sir!



another P. S. Make sure that you don't bypass your fuse.

 

[Sixpack]

I also have my bd shifter with the delay. In order for me to do this I installed the brake per the instuctions and then cut the yellow wire and attached one end to each of the 2 wires from the bd switch. Thus I'm just interupting the circuit to the ecm just as the rocker swich does (that comes in the kit). It's alot easier to turn on/off this way. Also I'm told if you use the ecm, when you set your cruise control the brake will take over if you pick up speed to slow you down, then the cruise will take back over when slowed enough and the brake shuts off automatically. However, I have not been able to make mine work this way for some reason . Phil

 

[dresslered]

Good point Sixpack. The yellow wire is just the continuation of the black wire after the toggle switch. Your cruise control/Jacobs should work perfectly given the method of your install. My guess is that the cruise control has just never completely shut off enough for the Jacobs to engage. Try going down a good hill and I am sure you will find that it works just fine.

 

[CFAR]

https://www.turbodieselregister.com/user_gallery/displayimage.php?&photoid=6941&width=0

Can also be viewed in my readers rigs gallery

This is how I did mine.



If you simply splice a switch into the yellow comming off of the Jacobs switch, you have simply changed the place you turn on the brake.

Since I use my brake all the time, I wanted a quicker turn on and off, also I didn't like sitting at a light with the brake on, then when I went to take off it would bog down.



So I ran a hot wire from the fuse panel to my new shifter switch, then ran a wire from the switch to the yellow wire,(without cutting yellow wire).

This way I can leave the jake switch off and use the shifter switch to turn on brake or vice versa. I don't like the idea of back feeding the ecm 12v's so I never turn on the jake switch and the shifter switch at the same time. I've had mine like this for a couple years without any problems. My Jake is starting to stick, so I guess I will have to take a look at it, anyone have any ideas?