DTC 21: Shorted Communication Line Circuit
- Check ETACS-ECU 16-pin connector C-111, column switch 10-pin connector C-86, front-ECU 17-pin connector A-09X and sunroof motor assembly (if equipped) 10-pin connector for loose, damaged or corroded terminals. See Figure
, Figure
and Fig 1
. If problem exists, repair connector as necessary and recheck for DTCs. If problem does not exist, go to next step.
- Check for open or short in Blue/White wire between ETACS-ECU connector C-111 terminal No 42, column switch connector C-86 terminal No. 3, sunroof motor assembly connector and front-ECU connector A-09X terminal No. 17. See Figure
, Figure
and Figure
. If problem exists, repair Blue/White wire as necessary and recheck for DTCs. If problem does not exist, go to next step.
- Disconnect column switch connector C-86, test system operation and check for DTCs. If DTC 21 does not set (DTC 12 sets), replace column switch and ensure DTCs 12 and 21 do not reset. If DTC 21 sets, go to next step.
- Disconnect front-ECU connector A-09X. Test system operation and check for DTCs. If DTC 21 does not set (DTC 13 sets), replace front-ECU and ensure DTCs 13 and 21 do not reset. If DTC 21 sets, replace ETACS-ECU and recheck for DTCs.
- Disconnect sunroof motor assembly connector, test system operation and check for DTCs. If DTC 21 does not set (DTC 13 sets), replace sunroof motor assembly and ensure DTCs 13 and 21 do not reset. If DTC 21 sets, replace ETACS-ECU and recheck for DTCs.
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.