The exhaust brake trick on a '98 Cummins that nobody talks about

I accidentally figured out that tapping the Jake brake switch three times fast while holding the throttle at 1500 RPM actually kicks the turbo vane open just enough to clear a stuck solenoid, and I only found it because I was angrily jabbing at it after 45 minutes of roadside troubleshooting near Flagstaff.

2 comments

2 Comments

adam_patel9d ago

Yeah @river_allen, did your truck have the older Cummins ECM or the updated one? I've heard the later '98 models got a different calibration that makes that vane trick hit or miss. I'm honestly surprised I didn't stall out like you did, but I bet the altitude and the specific solenoid part number are the real variables here. Flagstaff elevation messes with the fuel timing so bad, it probably amplified whatever your truck was already fighting. Have you tried swapping just the solenoid itself or did you go for the whole actuator assembly?

river_allen9d ago

Flagstaff's got that elevation, makes these trucks act weird. I tried that same sequence on my '97 after reading a diesel forum post and it just made my truck stall out twice before the CEL popped on. Might work for a specific solenoid part number or a truck that wasn't built on a Tuesday... most of these 12 valves don't have the same vane geometry.