Jake Problems

[Big Ike]

Hi can anyone help me,i have a 2004 RD690S the jake does not work at all,i apply battery voltage to the terminal on either jake housing and the jake works,i neec a wiring schmatic and or any advise on the next troubleshooting step.Thanks

[HK Trucking]

Check to make sure the switch on the clutch pedal is not out of adjustment or defective.

That's a common cause of no Jake brake operation.

[Packer]

I don't have the smarts to draw a schmatic and poet it but - - - the power flow is:

1)From the 'Hot' buss bar to a fuse or breaker

2)Fuse or breaker to the dash switch

3)Then I run mine to the clutch switch (As HK stated, "Adjusted correctly")

4)Clutch switch to the pump/fuel linkage switch (Adjusted correctly)

5)To the Jake boxes

A test light or multimeter clipped onto each switch will help troubleshoot and adjust each switch.

Might also check for broken wire or loose connections

I can't remember a switch ever going bad but it can happen.

Usually just needs tweeking.

Packer

[rhasler]

I don't have the smarts to draw a schmatic and poet it but - - - the power flow is:

1)From the 'Hot' buss bar to a fuse or breaker

2)Fuse or breaker to the dash switch

3)Then I run mine to the clutch switch (As HK stated, "Adjusted correctly")

4)Clutch switch to the pump/fuel linkage switch (Adjusted correctly)

5)To the Jake boxes

A test light or multimeter clipped onto each switch will help troubleshoot and adjust each switch.

Might also check for broken wire or loose connections

I can't remember a switch ever going bad but it can happen.

Usually just needs tweeking.

Packer

Good advice as relates to a manual engine, however in the 2004 chassis the engine is fully electronically controlled. The VECU sends a command to the EECU to activate the engine brake based on throttle position, engine brake dash switch position, and clutch switch position. The EECU sends power to the engine brake based on the VECU command. Fuse 16 in the cab powers both the engine brake switch in the dash and the clutch switch. Check both of these switches for power on the wires from circuit 16. As indicaated earlier, make sure the clutch switch is adjusted properly and that it is operating correctly.

[poonamt93]

Sounds like you have a malfunction in the control system for the Jake. The brake is obviously working since it engages.

It could be in the ECM, it could also be a bad sensor feeding faulty information to the ECM. It may even be part of the mechanical controls, even a bad switch that occasionally shorts.

It sounds like you have a good idea what caused it, but don't want it repaired by a shop that burned you once already. Ask around, find a shop you trust, and take it there. Any shop that does consistently bad work will become infamous among truckers. They tend to talk, and they vote on a shop by driving right past it.