03 - Multiplex Control Unit Can't Receive Signals From Itself

03 - The Multiplex Control Unit Cant Receive Signals From Itself


DTC 3 only (no other DTCs present):
Substitute a known-good multiplex control unit, and recheck for the DTC.

DTC 1, 2, and 3 (ECM/PCM P0600) simultaneously:
Check for a short to body ground in the YEL wire between multiplex control unit terminal E10 and ECM/PCM terminal E24, and in the GRN/RED wire between multiplex control unit terminal K10 and gauge assembly terminal A1.

If both wires are OK, substitute a known-good multiplex control unit, gauge assembly, and ECM/PCM one at a time, in that order, and recheck for the DTCs after each substitution.



Reprogram the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.