cm871 engine brake prob

[wellrun]

cm871 isx engine brake at 66% even when switch is at #3 position...2009 prostar

[alamow]

Check Oil pressure. The engine in the truck I drive has the same issue when oil pressure drops below 32 psi.

Do you have full engine brake when the engine is cold?

[Rawze]

(01-06-2019 )alamow Wrote:  Check Oil pressure. The engine in the truck I drive has the same issue when oil pressure drops below 32 psi.

Do you have full engine brake when the engine is cold?

If your oil pressure is dropping down below 32 psi while driving then you have some serious problems there.

[wellrun]

Yes i have insite and it show 66% when the switch is in #3... it should be @100%

[Nilao]

Most likely a bad switch then.

[in2trux]

Could also be the engine brake harness.
1 bad clip and it will throw codes.

We were losing stage 3
Stage 1 and 2 worked fine. Stage 3, coded.
New harness, no more problem.

[wellrun]

no codes

[Rawze]

(01-06-2019 )wellrun Wrote:  cm871 isx engine brake at 66% even when switch is at #3 position...2009 prostar

Bad programming can cause incorrect engine brake operation too.