DTC Troubleshooting: 59
DTC 59:
 BRKDIAG High
  1. Turn the ignition switch to LOCK (0).
  1. Check the brake lights without pressing the brake pedal.
Are the brake lights on?
YES -
Replace the relay circuit board.■
NO -
Go to Step 3 .
  1. Turn the ignition switch to ON (II).
  1. Check the brake lights without pressing the brake pedal.
Are the brake lights on?
YES -
Go to Step 5 .
NO -
Go to Step 13 .
  1. Turn the ignition switch to LOCK (0).
  1. Disconnect the VSA modulator-control unit 47P connector.
  1. Turn the ignition switch to ON (II).
  1. Check the brake lights without pressing the brake pedal.
Are the brake lights on?
YES -
  • With ACC: Go to Step 9 .
  • Without ACC: Repair short to body ground in the wire between the VSA modulator-control unit 47P connector No. 35 and the under-hood fuse/relay box connector D (10P) terminal No. 7.
NO -
Go to Step 27 .
  1. Turn the ignition switch to LOCK (0).
  1. Disconnect the adaptive cruise control (ACC) unit 20P connector.
  1. Turn the ignition switch to ON (II).
  1. Check the brake lights without pressing the brake pedal.
Are the brake lights on?
YES -
Repair short to body ground in the wire between the VSA modulator-control unit 47P connector No. 35 and the under-hood fuse/relay box connector D (10P) terminal No. 7.■
NO -
Replace the adaptive cruise control (ACC) unit.■
  1. Clear the DTC with the HDS.
  1. Press the brake pedal for 3 seconds or more.
  1. Check for DTCs with the HDS.
Is DTC 59 indicated?
YES -
Go to Step 16 .
NO -
Go to Step 27 .
  1. Turn the ignition switch to LOCK (0).
  1. Short the SCS line with the HDS.
  1. Disconnect the ECM/PCM connector A (44P) or the ECM/PCM connector A (49P).
  1. Disconnect the brake pedal position switch 4P connector.
  1. Check for continuity between brake pedal position switch 4P connector terminal No. 2 and ECM/PCM connector A (44P) terminal No. 40 *1 or ECM/PCM connector A (49P) terminal No. 42 *2 .
    *1: R20A3 engine model
    *2: K24Z3 engine model
Is there continuity?
YES -
Go to Step 21 .
NO -
Repair open in the wire between the ECM/PCM and the brake pedal position switch.■
  1. Reconnect all connectors.
  1. Update the ECM/PCM if it does not have the latest software: R20A3 engine model, K24Z3 engine model, or substitute a known-good ECM/PCM: R20A3 engine model, K24Z3 engine model.
  1. Clear the DTC with the HDS.
  1. Turn the ignition switch to LOCK (0), then turn it to ON (II) again.
  1. Press the brake pedal for 3 seconds or more.
  1. Check for DTCs with the HDS.
Is DTC 59 indicated?
YES -
Go to Step 27 .
NO -
If the ECM/PCM was updated, troubleshooting is complete. If the ECM/PCM was substituted, replace the original ECM/PCM: R20A3 engine model, K24Z3 engine model. ■
  1. Turn the ignition switch to LOCK (0).
  1. Update the VSA modulator-control unit if it does not have the latest software. If the unit already has the latest software, substitute a known-good VSA modulator-control unit.
  1. Turn the ignition switch to LOCK (0), then turn it to ON (II) again.
  1. Press the brake pedal for 3 seconds or more.
  1. Check for DTCs with the HDS.
Is DTC 59 indicated?
YES -
Check for loose terminals in the VSA modulator-control unit 47P connector. If the VSA modulator-control unit was updated, substitute a known-good VSA modulator-control unit, then retest. If the VSA modulator-control unit was substituted, go to Step 1 .
NO -
If the VSA modulator-control unit was updated, troubleshooting is complete. If the VSA modulator-control unit was substituted, replace the original VSA modulator-control unit. If any other DTCs are indicated, go to the indicated DTCs troubleshooting.■

R20A3 engine model
K24Z3 engine model