Community Forums

cadiwa · 08-12-2014, 08:42 PM

When I take my foot off the throttle I get no downshift & no brake activation. I have checked the fuse for the PAC Brake. If I energize the solenoid with 12v the air cylinder does close the exaust butterfly. Any ideas?

slickest1 · 08-12-2014, 10:09 PM

Try turning off the cruise control. The truck I drive with a Cat C12, will not let the Jake work with the cruise on. I know it is different than a pac brake but worth a try. My coach with a ISC Cummins will sometimes do the same thing.

Skip426 · 08-12-2014, 10:19 PM

Could be a communication problem or a relay .
System wants to see , zero throttle signal from the TPS, so binding pedal due to carpet ; or as was my case rusted hinge. Others have reported switch trouble , not passing power to the system even though the light is on. With the no downshift displayed I'd, look at the switch. If the trans control showed 2 and no activation I'd think relay.
You would need a wiring schematic for your coach to track down a relay , if in fact it has one , but most do.
My coach has 2 relays for exhaust brake

and I don't know why , and hope I never have to find out.