Exhaust brake weirdness...

[JCleary]

I have installed a PacBrake PRXB. It's awesome. I can't say enough good about it.



I have noticed that the ECM has some peculiar traits when the E-brake is on. For instance:



-Cold start, let the truck idle a minute, put in gear (D or R, doesn't matter) and take foot off the brake. The brake will cycle off and on, off and on, off and on until you accelerate away. If you drive over 15mph and slow back down, the cycling does not repeat. Subsequent starts and idling away does not cause cycling. It only happens after a "cold soak. "



-Another strange behavior is that the brake tries to engage when idling down a hill when in 1st gear. We all know the TC does not lock on a stock trans in 1st, but the e-brake (controlled by the ECM) tries to engage the brake and immediately disengages. When going down a hill with the switch on in 1st I hear Psht-psht-psht-psht-psht-psht until I turn the switch off.



I know, the easy solution is to turn off the switch. My preference is to leave it on all the time.



Anyone else notice this behavior, whether with a Jake, BD or PacBrake? I'm reasonably confident that it's an ECM quirk, not a brake issue.

 

[ScottLewis]

My '06 holds the brake on at idle until the engine reaches operating temps. This only happens at or very near dead stop. I suspect that your ECM is reading and/or misinterpreting info from the speed sensor or TPS that's causing the cycling effect.

Hopefully, someone with more expertise about the Pac while give you some idea how to track it.



Dan

 

[Pacbrake]

your going to have to take the truck to your Chrysler dealer it sounds as if the ECM & Temp sender are creating the issue. as for the cycling on/off first thing in the morning that is normal.