DTC Troubleshooting: 30

Adaptive Cruise Control (ACC) Unit DTC 30:
Adaptive Cruise Control (ACC) Relay Circuit Malfunction
  1. Check the brake lights without pressing the brake pedal.
Are the brake lights off?
YES -
Go to Step 10 .
NO -
Go to Step 2 .
  1. Check the brake lights without pressing the brake pedal.
Are the brake lights off?
YES -
Intermittent failure. The system is OK at this time. Check for loose or poor connections.■
NO -
Go to Step 4 .
Is the brake pedal position switch OK?
YES -
Go to Step 5 .
NO -
Is the relay OK?
YES -
Go to Step 6 .
NO -
Replace the relay and recheck.■
  1. Disconnect the 4P connector from the brake pedal position switch.
  1. Check for voltage between the brake pedal position switch 4P connector No. 2 terminal and body ground.
Is there battery voltage?
YES -
Repair a short to power in the wire.■
NO -
Go to Step 8 .
  1. Disconnect the adaptive cruise control (ACC) unit 20P connector.

  1. Check for voltage between the adaptive cruise control (ACC) unit 20P connector No. 1 terminal and body ground.
Is there battery voltage?
YES -
Repair a short to power in the wire between the adaptive cruise control (ACC) unit and the adaptive cruise control (ACC) relay, or between the adaptive cruise control (ACC) unit and the brake lights circuits.■
NO -
  1. Clear the DTCs with the HDS.
  1. Turn the main switch ON.
  1. Check the brake lights with the brake pedal pressed.
Do the brake lights come on?
YES -
Go to Step 13 .
NO -
Go to Step 36 .
  1. Check for DTCs with the HDS.
Is DTC 30 indicated?
YES -
Go to Step 14
NO -
Go to Step 20 .
  1. Turn the ignition switch OFF.
  1. Remove the adaptive cruise control (ACC) relay.
  1. Disconnect the 20P connector from the adaptive cruise control (ACC) unit.
  1. Disconnect the brake pedal position switch 4P connector.

  1. Check for continuity between the adaptive cruise control unit 20P connector No. 1 terminal and body ground.
Is there continuity?
YES -
Repair a short to ground in the wire between the adaptive cruise control (ACC) unit and the adaptive cruise control (ACC) relay.■
NO -
Go to Step 19 .

  1. Check for continuity between the adaptive cruise control (ACC) unit 20P connector No. 1 terminal and adaptive cruise control (ACC) relay 5P connector No. 1 terminal.
Is there continuity?
YES -
NO -
Repair an open in the wire between the adaptive cruise control (ACC) unit and the adaptive cruise control (ACC) relay.■
Is the relay OK?
YES -
Go to Step 21 .
NO -
Replace the relay and recheck.■
  1. Remove the adaptive cruise control (ACC) relay.

  1. Check for voltage between the adaptive cruise control (ACC) relay 5P connector No. 2 terminal and body ground.
Is there battery voltage?
YES -
Go to Step 23 .
NO -
Repair an open in the wire between the No. 13 (20 A) fuse in the under-hood fuse/relay box and the adaptive cruise control (ACC) relay.■
  1. Turn the ignition switch ON (II).

  1. Check for voltage between the adaptive cruise control (ACC) relay 5P connector No. 5 terminal and body ground.
Is there battery voltage?
YES -
Go to Step 25 .
NO -
Repair an open in the wire between the No. 29 (7.5 A) fuse in the under-dash fuse/relay box and the adaptive cruise control (ACC) relay.■
  1. Turn the ignition switch OFF.
  1. Disconnect the 20P connector from the adaptive cruise control (ACC) unit.

  1. Check for continuity between the adaptive cruise control (ACC) unit 20P connector No. 16 terminal and body ground.
Is there continuity?
YES -
Repair a short to ground in the wire between the adaptive cruise control (ACC) unit and the adaptive cruise control (ACC) relay.■
NO -
Go to Step 28 .

  1. Check for continuity between the adaptive cruise control (ACC) unit 20P connector No. 16 terminal and adaptive cruise control (ACC) relay 5P connector No. 3 terminal.
Is there continuity?
YES -
Go to Step 29 .
NO -
Repair an open in the wire between the adaptive cruise control (ACC) unit and the adaptive cruise control (ACC) relay.■
  1. Install the adaptive cruise control (ACC) relay.
  1. Reconnect the adaptive cruise control (ACC) unit.
  1. Clear the DTCs with the HDS.
  1. Turn the ignition switch ON (II) and the main switch ON.
  1. Select the ACC from the DRIVING SUPPORT menu, then enter ACC RELAY from the FUNCTION TEST menu.
  1. Do the adaptive cruise control (ACC) relay function test.
  1. Check for DTCs with the HDS.
Is DTC 30 indicated?
YES -
NO -
Troubleshoot the indicated DTC. If there is no DTC, the system is OK at this time.■
  1. Check for the DTCs with the HDS.
Is DTC 30 indicated?
YES -
Go to Step 37 .
NO -
Go to Step 43 .
Is the relay OK?
YES -
Go to Step 38 .
NO -
Replace the relay and recheck.■
  1. Remove the adaptive cruise control (ACC) relay.
  1. Disconnect the adaptive cruise control (ACC) unit 20P connector.
  1. Disconnect each brake light 4P connector and the high mount brake light 2P connector.

  1. Check for continuity between the adaptive cruise control (ACC) unit 20P connector No. 1 terminal and body ground.
Is there continuity?
YES -
Repair a short to ground in the wire between the adaptive cruise control (ACC) unit and the adaptive cruise control (ACC) relay.■
NO -
Go to Step 42 .

  1. Check for continuity between the adaptive cruise control (ACC) unit 20P connector No. 1 terminal and adaptive cruise control (ACC) relay 5P connector No. 1 terminal.
Is there continuity?
YES -
NO -
Repair an open in the wire between the adaptive cruise control (ACC) unit and the adaptive cruise control (ACC) relay.■
  1. Check the brake light and high mount brake light bulbs.
Are the bulbs OK?
YES -
Go to Step 44 .
NO -
Replace the light.■
  1. Check the brake lights with the brake pedal pressed.
Do the brake lights come on?
YES -
Intermittent failure. The system is OK at this time. Check for loose or poor connections.■
NO -
Repair an open in the BLK wire or poor ground (G701).■