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Ecu Malfunction C0550

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#1 jthunts



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Posted 03 December 2010 - 08:44 AM

I had to replace dead battery in the wifes 02' Trailblazer. Well after installing new battery "Service 4WD" light came on. So I took it over to a buddy who had a scanner and got this code "C0550" ECU Malfunction. We tried clearing it and it came back immediately. Just wondering what parts I need to replace. Thanks in advance

#2 sparkstech


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Posted 03 December 2010 - 04:50 PM

At each power-up, the transfer case shift control module runs a self-test on the following:
EEPROM Checksum
ROM Checksum
RAM Checksum
RAM Malfunction

These are all checks internal to the module itself. Any module that has a *550 code needs to be replaced. For the code to be read the module must have power and ground and the data line must be functioning so if you can read the code the module is bad, nothing else to check.
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#3 twavor



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Posted 06 April 2011 - 05:03 PM

Sorry to bring up an old post, but was searching for the code C0550 and this is the only thread that comes up here....got an '02 Envoy I just replaced the transfer case in today that did the same thing....Is everyone 100% positive the TCCM is out? Kind of a pisser that transfer is out and the TCCM throws craps on the same day.

Southern IA farmer and ASE certified master auto technician
'00 Silverado ecsb 4x4, 5.3 and riding on 285's...newest vehicle I've ever owned, loads of fun, and I've got cupholders!
'75 GMC 3/4t 4x4--355, 4spd, 205 t-case, 14 bolt full floater.
Built to haul a load--10+leaves in the rear, 1000lb overload shocks, 5 leaves in the front. Bulletproof and built like a brick sh*thouse!