HELP how do I stop these throttle pot faults and derates
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- เผยแพร่เมื่อ 29 มี.ค. 2024
- This was a problem that stumped engine shop Joe. Lets take a look at what was wrong and how it got corrected. Stop the video along the way and see if you can figure out what to do to properly correct this issue. It almost made me cry.. and engine shop joe has very few tears of frustration left!
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Joe this video was an awesome one. I love these kind of real trouble shooting steps. Hats off to this one.
Great video and case study Joe! 5V supply codes can be tricky at times especially when the circuits involved have different set criteria and they are intermittent. As mentioned, I have also seen similar issues on some Paccar trucks where 5V supply 2 was shared for APS 2, coolant level sensor 5V (used on immersion type, not non-immersion reed switch style), and DPF delta pressure sensor. Fixed a few deleted ones that they put multiple electronic foot pedal assy and the issue was a rubbed harness at the DPF. Trouble I find is the 5V circuits are not always labeled well and can be used on OEM connector and Cummins side but doesn't really tell you if shared always on Cummins or OEM wiring diagram.
Fixed an 2005 T800 with CM850 ISL past summer for another fleet in area that had the parts cannon unloaded on it by the customer, dealer, and Cummins tech support. Here is cut and paste from my repair order what I found on it:
Customer concern: Check Engine Light comes on intermittently and loss of power. Customer has replaced barometric pressure sensor, oil pressure sensor, Engine ECM and checked wiring from sensors to ECM for both replaced sensors.
Connected Cummins Fault viewer and pulled all truck faults. FC 0352- Sensor Supply Voltage #1 Circuit - Voltage below normal, or shorted to low source had 59 Inactive counts. Reviewed Cummins T/S for FC0352. Checked for proper voltage, grounds, and signal for barometric and oil pressure sensor at sensors and ECM. All checked okay. When checking wiring, noticed signal wire from ECM to barometric pressure sensor had been over-layed. Tugged at both butt connectors to check integrity of repair and connector at ECM pulled apart. Replaced with new heat shrink butt connector. Retrieved Kenworth wiring diagram P94-1494 to check for 5V supply on OEM harness. Found pin 21 was 5V supply for coolant level sensor and remote throttle. The Cummins ISL 850 diagram and Kenworth p94-1494 didn't state if sensor supply 1, 2, 3 or 5, but Cummins diagram for ISBe CM850 and QSL CM2850 showed pin 21 on OEM side as 5V sensor supply #1. Located connector J09 of engine harness and shorted Pin G(5V CLS) to ground and monitored 5V at barometric pressure sensor- voltage dropped low and FC 0352 went active. Started inspecting OEM engine harness. Found wire BRN/GRY WIRE103 rubbed in spot to bare copper and rubbing refrigerant high pressure hose steel end shorting it to ground. Repaired wiring by unpinning wire from connector and slip heat shrink over rub on wire and other wires with rubs. Also repaired wires on cooling module harness the same way. Re-routed harness to prevent rubbing and properly secured wiring. The engine harness could use more attention for proper routing and stand-off placement to prevent future issues. Checked other fault codes. Codes for coolant level circuit. The 5V supply isn't used because updated two pin sensor Q21-1026. Disconnected sensor and found corrosion in connector terminals from seeping sensor. Replaced terminals in MP280 connector and let customer replace CLS. Cleared fault codes and took on test drive. No fault codes were set. Released truck to customer.
Truck hasn't an issue since and have helped them fix multiple other trucks since.
Happy Easter to all.
Perfect Repair.💪
There was a problem on the buses. The shield on long remote accel. pedal would go bad, and wire started to pick up EMI interferences, causing the same code to set off.
if your working on a paccar product there is a five volt regulator going to the low coolant sensor that is not on any drawing but if it fails you get 12 volts to the sensor, they have a two amp fuse in the cab pd box, my fix was to remove the fuse and tap into any five volt wire from the ecm, this applies only to trucks with the coolant level fuse in the pd box, they did away with in on later models, also the first aftertreatment system the top rear screw in the step would poke the harness and short out all the ecm five volts.
Thanks for sharing this 👍🏼
I think you just answered a long lived problem I have had with a coolant level sensor. I never knew or heard of this regulator. Thanks man.
Kind of remember some trucks having a separate module if they had the Kysor warning/shutdown system on them, but many years ago. Switched many of the three wire immersion style sensors over to the "less" fail prone two wire one. Also had to add a 5V supply to a KW glider that used the non-immersion sensor with a CM875 ISM.
@@stevesauerland223 hey Steve was the 3 wire the Emerson style sensor and the 2 wire the non Emerson style?
@@jaywyatt7476 Two wire was also immersion, Q21-1026 if memory serves me correct. What year truck/radiator style do you have?