DTC 91-1: SH-AWD Control Unit Programming Error
Note. Before you troubleshoot, review the general troubleshooting information (see GENERAL TROUBLESHOOTING INFORMATION ). DTC 91-1 is stored when the SH-AWD system update is not completed. Do not turn the ignition switch OFF while updating the SH-AWD system. If you turn the ignition switch OFF before completion, the SH-AWD system can be damaged.
- Do the SH-AWD system update procedure (see «UPDATING THE SH-AWD CONTROL UNIT»(/acura/mdx/ii-2006-2010/remont/differentials-drive-axles/#rear-differential__updating-the-sh-awd-control-unit) ).
- Check for DTCs with the HDS. Is DTC 91-1 indicated? YES -Update the SH-AWD control unit if it does not have the latest software (see «UPDATING THE SH-AWD CONTROL UNIT»(/acura/mdx/ii-2006-2010/remont/differentials-drive-axles/#rear-differential__updating-the-sh-awd-control-unit) ), or substitute a known-good SH-AWD control unit (see «SH-AWD Control Unit Replacement»(/acura/mdx/ii-2006-2010/remont/differentials-drive-axles/#rear-differential__sh-awd-control-unit-replacement) ) and recheck. If the symptom/indication goes away with the updated SH-AWD control unit, troubleshooting is complete. If the symptom/indication goes away with a known-good SH-AWD control unit, replace the original SH-AWD control unit (see «SH-AWD Control Unit Replacement»(/acura/mdx/ii-2006-2010/remont/differentials-drive-axles/#rear-differential__sh-awd-control-unit-replacement) ). NO -Update is complete.