E-brake switch on shifter - which wires

[Blue Goat]

How is everyone wiring the BD switch on the Jacobs E-brake system. Are you using the OEM switch? If so, how are your wiring it?

2001. 5 Truck

 

[Thomas]

Look at Fig. 25 of the installation manual. It should show four wires (yellow, green, black, white) at the lighted toggle switch. The only purpose of the white and green at the switch is to power the indicator light in the switch—they have nothing to do with brake operation.

Your shift lever mounted switch needs to connect/disconnect the black and yellow wires. These are the wires that connect pin 20 of the ECM with the powered side of the vacuum solenoid.

 

[TowPro]

Does pin 20 from the ECM really go directly to the Vacuum switch? or is there some kind of relay or isolation circuit in there. Kind of hard to beleve that the ECM will sink enough current to do anything more then fire an electronic relay.

I guess what I am asking is (those of you with the Jacobs or Pac) can I hook the BD directly to pin 20?

Originally posted by Thomas:


Your shift lever mounted switch needs to connect/disconnect the black and yellow wires. These are the wires that connect pin 20 of the ECM with the powered side of the vacuum solenoid.

 

[Thomas]

The E-brake by Jacobs has ECM pin 20 connected to the vacuum solenoid and the solenoid connected to ground. You could get into trouble if the BD solenoid allowed more current to flow.

 

[TowPro]

Thats what I was thinking. I was thinking about putting an opto isolator between it and a relay, that way I don't even have to worry about the spike from the relay coil let alone the spike that big vacuum solenoid would have when the EMF field collapes (electronic talk). But then again, there must be protection built into the ECM from the factory, maybe a call to Cummins is in order for this one

Originally posted by Thomas:
The E-brake by Jacobs has ECM pin 20 connected to the vacuum solenoid and the solenoid connected to ground. You could get into trouble if the BD solenoid allowed more current to flow.

 

[Blue Goat]

Thanks for all the input. It is good to have a place to get questions answered.

 

[MikeR]

When I installed my shifter mounted switch,I never installed the original Jacobs switch at all. In fact I cut off the connector and the two extra wires since I didn't use the Jacobs switch. Thomas described which remaining wires to use.

-Mike

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'00 2500QC,4x4,LWB,Dark Garnet,6spd,3. 54lsd,SLT,DD stage II,Psychotty air,10-level PM3,Jacobs ebrake,Isspro pyro & boost gauges,2wd-low,Airoquip fuel lines,Smittybilt nerfs,BFG 285/75 AT's,Midland cb,Clarion 6-disc changer