The yellow "check engine" light came on yesterday during normal operation: 1450 RPM and 68 MPH were the set parameters. We pulled off at the next exit and checked that all engine functions were normal. I had a similar experience a few years and suspected it was a false "vehicle speed " code so I cleared the light and chime using the ignition key procedure. More on that later. There happened to be a diesel engine shop just two mile down the road so I went there and had them use a code reader to verify my suspicions and sure enough there was a stored "vehicle code " I had them clear it and we where on our way. About ten miles down the road it happened again. However, I was watching the gauges like a hawk and noted several very rapid RPM fluctuations. I turned off the cruise control and drove "manually" for a couple miles with no RPM fluctuations. Reengaged the cruise and fluctuation returned. I repeated this several times before we got to a suitable place to pull off the interstate. Cleared the light and chime again with the ignition switch and drove the last 200 miles manually and had no issues. I am not familiar with how the cruise actually works so help me out. Is this something I can fix? Is it air controlled? Worn gears slipping? Electric gremlins? I'm not looking forward to "hand flying " the next 2500 miles.
With your engine/trans. being a "fly by wire" system it is most likely electric gremlins related to turbine speed sensor. If it was a loose connection in one of the plugs it would happen all the time. With it only happening during cruse leads back to electric static in that circuit. Now remember this is a WAG this A/M
Mike
Just one time a couple of years ago, our 97 U295 Cat did this. Only once. Was playing with cruise buttons, because it was off, when I thought it was on. So I hit them a bunch of times. I turned the cruise off, then reset everything.
Never did it again. Silverleaf showed no err codes.Was very daunting when it did it. That was 6K+ miles ago. Just a side note. Engine has been out, all connections clean.
Chris
http://ww2.justanswer.com/uploads/JCTech012/2009-11-13_110804_FC242.pdfGuided Step 3 - Clear the fault code.
Guided Step 3A - Disable the fault code.
Action
verify that the speed reported by the
electronic service tool is accurate or
reasonable for the current gear.
(For example: 40 mph in top gear is
probably inaccurate data.)
OK NOT OK
Vehicle speed is accurate for current gear Vehicle speed read by electronic service
tool is inaccurate. Verify VSS parameters
are adjusted correctly in the ECM. Check
VSS and OEM harness in Steps 2A and 2B
above. Repair any problems found.
Fault Code 241 Go to 3A
Conditions
Connect all the components.
Action
disable the fault code.
Turn keyswitch "OFF".
Turn keyswitch "ON" (do not start
engine).
Note: Vehicle speed and engine speed
must be 0 for at least 30 seconds to
disable the fault code.
Fault Code 242 inactive Return to troubleshooting steps or contact
your local Cummins Authorized Repair
Location if all steps have been complete and checked again