Escalade EXT V8-6.0L VIN N (2004)
Control Module: Technical Service Bulletins
Drivetrain - Transfer Case Control Module Replacement
Bulletin No.: 05-04-21-002
Date: March 10, 2005
INFORMATION
Subject:
Guidelines for Replacement of Transfer Case Control Module (TCCM)
Models:
2005 and Prior Light Duty Trucks
with New Venture Gear (NVG) Transfer Case (RPOs NP1, NP4, NP8)
Dealers are replacing the TCCM unnecessarily.
Dealers are replacing the TCCM with codes stored in HISTORY only. The TCCM does not have a current fault condition when tested.
Parts reviewed at the Warranty Parts Center (WPC) have a 75% No Trouble Found (NTF) rate. The only two legitimate reasons to replace the TCCM
are:
^
Diagnostic Trouble Code (DTC) C0550
^
NO Communication with a scan tool.
DTC C0550
This DTC indicates that the module has an internal fault and should be replaced.
No Communication
^
The no communication conditions referenced here are also caused by a module internal fault to a point where the module physically will not talk. A
technician cannot pull DTCs from the module because it will not communicate. The module is electrically dead.
^
No communication is not to be confused with a U1026 code. This code tells the technician that the module may still be functioning but is temporarily
off line. This code may be set by the Instrument Panel (IP) or the Powertrain Control Module (PCM) against the TCCM. The technician needs to
figure out why the module went off line. These are typically caused by connection concerns. There is no need to replace a TCCM for a U1026 DTC.
Diagnostic Aids
^
When diagnosing a transfer case electrical control system, ALWAYS check power and ground wiring first.
^
Test the connections for intermittent or poor connections, complete plug insertion, bent pins, pushed out terminals and water contamination.
