Archived exhaust brake failure

[Guru]

truck is a 2001. 5 HO 6sp with mopar Jake Rambrake. Problem is loss

of output voltage from ECM. Only happens after cruise has set for 20 minutes. Warrentee at dealership changed ECM (didn't fix it).

Key off for 30 secs and funtions fine until cruise used(must on and set ,not just on). No other cruise problems. Happen in any outside temp. conditions. APPS functions checked ok. Please help as unit is a tow truck that misses its exhaust brake!

 

[emjay]

Has it been verified that the output voltage from the ECM is incorrect? If so, it possibly might be one or both of the idle validation switches. Another possibility is an intermittent solenoid/relay, or intermittent short.



If I remember correctly, the cruise control mechanism changed in recent years, eliminating the vacuum servo. If your truck is equipped with the vacuum servo system, the cruise control servo/cable/linkage may be sticking or misadjusted, and thus preventing complete closure of the throttle, which would prevent the exhaust brake output from switching on. Since both the cruise and exhaust brake use vacuum, you may want to check the vacuum with a gauge when the symptom occurs.



In any case, verification of true idle condition should be confirmed when the exhaust brake output is off and is expected to be on.

 

[Guru]

dealer is replacing the APPS . We will see. thanks.