02 - Multiplex Unit Can't Receive Signals From the ECM/PCM
02 - Multiplex Control Unit Can't Receive Signals From the ECM/PCMDTC 2 only (no other DTCs present):
Substitute a known-good multiplex control unit and a ECM/PCM one at a time, in that order, and recheck for the DTCs after each substitution.
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.
DTC 2 and 5 simultaneously:
Check for an open in the YEL wire between multiplex control unit terminal E10 and ECM/PCM terminal E24.
If the wire is 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.