DTC Troubleshooting: B1906
DTC B1906:
 Immobilizer-Keyless Control Unit Lost Communication with Gauge Control Module (Tach) (A/T Message)
  1. Clear the DTCs with the HDS.
  1. Turn the ignition switch OFF, and then back ON (II).
  1. Wait for 6 seconds or more.
  1. Check for DTCs with the HDS.
Is DTC B1906 indicated?
YES -
Go to Step 5 .
NO -
Intermittent failure, the system is OK at this time. Check for loose or poor connections between the gauge control module (tach) and the immobilizer-keyless control unit.■
  1. Turn the ignition switch OFF.
  1. Connect the HDS to the data link connector, then turn the ignition switch ON (II).
  1. Select the BODY ELECTRICAL menu, then enter the UNIT INFORMATION.
  1. Check the condition of the gauge control module (tach) from the CONNECTED UNIT list.
Is NOT AVAILABLE indicated?
YES -
Go to Step 9 .
NO -
Go to Step 10 .
Are all inputs OK?
YES -
NO -
Repair the faulty input, then recheck the DTCs.■
  1. Turn the ignition switch OFF.
  1. Disconnect the gauge control module (tach) 36P connector.
  1. Turn the ignition switch ON (II).
  1. Measure voltage between the gauge control module (tach) 36P connector No. 17 and No. 18 terminals and body ground.
Are there battery voltage?
YES -
Go to Step 14 .
NO -
Check the No. 16 (15 A) fuse in the under-hood fuse/relay box and the No. 10 (7.5 A) fuse in the under-dash fuse/relay box. If the fuse is blown, replace the fuse and recheck the DTCs. If the fuses are OK, repair an open in the wire between the under-dash fuse/relay box and the gauge control module.■
  1. Turn the ignition switch OFF.
  1. Check for continuity between the gauge control module (tach) 36P connector No. 15 and No. 16 terminals and body ground.
Are there continuity?
YES -
Go to Step 16 .
NO -
Repair an open in the wire or poor ground (G502, G503).■
  1. Disconnect the under-dash fuse/relay box connector Q (16P).
  1. Check for continuity between the under-dash fuse/relay box connector Q (16P) No. 6 terminal and the gauge control module (tach) 36P connector No. 21 terminal.
Is there continuity?
YES -
NO -
Repair an open in the wire.■