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Engine brake/retarder still won't work

Yahoo Message Number: 17372
As I previously reported, my ISL 370 engine brake does not want to kick in when I decellerate. Cummins changed the engine wire harness today and that didn't fix it. We are all scratching our heads now and Cummins will go back at it tomorrow morning. They're wondering if it could be an Allison issue. The transmission down shifts to fourth like it's supposed to, but the engine brake will not engage. The red light flickers once or twice, but it won't stay on. This engine has the engine retarder, not your typical exhaust brake that uses/restricts the exhaust to slow the vehicle. I did notice that after they changed my wiring harness, my turbo only drops to 2 psi when I decellerate. It used to go to zero. It stays at about 1 psi at idle no and never used to. I'm wondering if this could have anything to do with it. If the turbo stays engaged, then maybe the engine retarder system thinks the engine is not decelerating enough to take action. Just my theory, and the Cummins tech says 1-2 PSI from the turbo at idle is OK. If anyone has any words of wisdom on why the engine retarder won't work, I am all ears. Thanks a bunch.
 

Engine brake/retarder still won't work

Reply #1 –
Yahoo Message Number: 17373
As I previously reported, my ISL 370 engine brake does not want to kick in when I decellerate. Cummins changed the engine wire harness today and that didn't fix it. We are all scratching our heads now and Cummins will go back at it tomorrow morning. They're wondering if it could be an Allison issue. The transmission down shifts to fourth like it's supposed to, but the engine brake will not engage.
The red light flickers once or twice, but it won't stay on. This engine has the engine retarder, not your typical exhaust brake that uses/restricts the exhaust to slow the vehicle. I did notice that after they changed my wiring harness, my turbo only drops to 2 psi when I decellerate. It used to go to zero. It stays at about 1 psi at idle no and never used to. I'm wondering if this could have anything to do with it. If the turbo stays engaged, then maybe the engine retarder system thinks the engine is not decelerating enough to take action. Just my theory, and the Cummins tech says 1-2 PSI from the turbo at idle is OK. If anyone has any words of wisdom on why the engine retarder won't work, I am all ears. Thanks a bunch.

Larry, Debbie, Tiki & Tomi
USAF Retired

2003 36' Allure #30856