# check engine light on and trans light on while driving



## fixit (Sep 22, 2012)

I have a 2005 Monaco holiday rambler with a cummins isb 300 and a allison 2500 mh.
  The check engine light comes on as well as the trans light while driving.
I took it too cummins and the fault code is 241 'lead to change oem harness"
I took it to Allison tech and he found 2 codes
U0073 "CAN bus reset counter overrun
U0100 "Lost CAN communicatin with ecm"
  The allison guy said he had a problem like this in the past and rewired a plug to the ecm with a new pigtail that he spliced in. 
              Any thoughts ???????????   Fixit
I hate those intermittent electrical problems!!!!!!!!!!


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## LL1956 (Sep 23, 2012)

Does the engine or transmission degrade when the light comes on?
Does the light stay on all the time? or just on and off at times?


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## LEN (Sep 24, 2012)

Think I, would if you are handy, go searching all the plugin's on the trans and motor to the shift paneland reseat them. Then give it a try again. If it is intermittent it can be the chit's and $$$$$ to find the right spot. Just throwing parts at the problem just doesn't work. I have a very intermittent starter problem, no key to starter communication, had guy's in the know change out a bunch of relays to the tune of $400 and it still did it once again. Because it only fails now and again they thought they fixed the problem. So for my fix I installed a remote start switch in the motor bay and if/when it does fail for good I'll fix the problem.

LEN


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## fixit (Oct 5, 2012)

Len,
 thanks for the tips.
The rig is at the  cummins shop and they are throwin time and money at it.  OUCH!!!!!!!!!!
They are unplugging and testing fotr correct reistance, ohms etc.
then they found a direct short to ground which disapeared???????
                                                         lost on what to do?
                                                                       fixit


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## fixit (Oct 5, 2012)

when the check engine light comes on i loose cruise contol and jake break
the trns light is on as wella and the allison won't go through its normal range od D-1 through D-5
it is in DD and you really have to downshift manually on a grade/.
Then after 4 hours of driving the light decide to turn off and everything works fine.
then later or after it cools down they come back on.
   Cummins dealer has it and they are throwing money at it trying to track the problem down
                                                       fixit????????????


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