LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Acura >> 2012 >> TL Base >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> Electronic Throttle Control System >> DTC Troubleshooting >> DTC P1659: ETCS Control Relay OFF Malfunction
April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC P1659: ETCS Control Relay OFF Malfunction

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information (see GENERAL TROUBLESHOOTING INFORMATION ).
  1. Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.
  2. Clear the DTC with the HDS.
  3. Check for Pending or Confirmed DTCs with the HDS.

    Is DTC P1659 indicated? 

    YES  - Go to step 4.

    NO  - Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the ETCS control relay and the ECM/PCM. ■

  4. Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.
  5. Check the No. 18 DBW (ETCS) (15 A) fuse in the under-hood fuse/relay box.

    Is the fuse OK? 

    YES  - Go to step 6.

    NO  - Go to step  17.

  6. Remove the ETCS control relay (A) from the under-hood fuse/relay box.
    Fig 1: Identifying ETCS Control Relay On Under-Hood Fuse/Relay Box
    G08069616Courtesy of AMERICAN HONDA MOTOR CO., INC.
  7. Test the ETCS control relay (see POWER RELAY TEST ).

    Is the ETCS control relay OK? 

    YES  - Go to step 8.

    NO  - Replace the ETCS control relay, then go to step  23.

  8. Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.
  9. Measure the voltage between ETCS control relay 4P connector terminal No. 4 and body ground.
    Fig 2: Measuring Voltage Between ETCS Control Relay 4P Connector Terminal No. 4 And Body Ground
    G08069617Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there battery voltage? 

    YES  - Go to step 10.

    NO  - Replace the under-hood fuse/relay box (see REMOVAL AND INSTALLATION ), then go to step  22.

  10. Measure the voltage between ETCS control relay 4P connector terminal No. 1 and body ground.
    Fig 3: Measuring Voltage Between ETCS Control Relay 4P Connector Terminal No. 1 And Body Ground
    G08069618Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there battery voltage? 

    YES  - Go to step 11.

    NO  - Replace the under-hood fuse/relay box (see REMOVAL AND INSTALLATION ), then go to step  22.

  11. Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.
  12. Jump the SCS line with the HDS.
  13. Disconnect ECM/PCM connector C (49P).
  14. Check for continuity between ETCS control relay 4P connector terminal No. 2 and ECM/PCM connector terminal C4.
    Fig 4: Checking Continuity Between ETCS Control Relay 4P Connector And ECM/PCM Connector
    G08069619Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  - Go to step 15.

    NO  - Repair open in the wire between the ECM/PCM (C4) and the ETCS control relay, then go to step  23.

  15. Disconnect ECM/PCM connector A (49P).
  16. Check for continuity between ETCS control relay 4P connector terminal No. 3 and ECM/PCM connector terminal A29.
    Fig 5: Checking Continuity Between ETCS Control Relay 4P Connector Terminal No. 3 And ECM/PCM Connector
    G08069620Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  - Go to step  28.

    NO  - Repair open in the wire between the ECM/PCM (A29) and the ETCS control relay, then go to step  23.

  17. Remove the ETCS control relay (A) from the under-hood fuse/relay box.
    Fig 6: Identifying ETCS Control Relay On Under-Hood Fuse/Relay Box
    G08069621Courtesy of AMERICAN HONDA MOTOR CO., INC.
  18. Jump the SCS line with the HDS.
  19. Disconnect ECM/PCM connector C (49P).
  20. Check for continuity between ECM/PCM connector terminal C4 and body ground.
    Fig 7: Checking Continuity Between ECM/PCM Connector Terminal C4 And Body Ground
    G08069622Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  - Repair short in the wire between the ECM/PCM (C4) and the ETCS control relay, then go to step  23.

    NO  - Go to step 21.

  21. Check for continuity between ETCS control relay 4P connector terminal No. 1 and body ground.
    Fig 8: Checking Continuity Between ETCS Control Relay 4P Connector And Body Ground
    G08069623Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  - Replace the under-hood fuse/relay box (see REMOVAL AND INSTALLATION ), then go to step  23.

    NO  - Go to step  28.

  22. Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.
  23. Reconnect all connectors.
  24. Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.
  25. Reset the ECM/PCM with the HDS.
  26. Do the ECM/PCM idle learn procedure (see ECM/PCM IDLE LEARN PROCEDURE ).
  27. Check for Pending or Confirmed DTCs with the HDS.

    Is DTC P1659 indicated? 

    YES  - Check for poor connections or loose terminals at the ETCS control relay and the ECM/PCM, then go to step  1.

    NO  - Troubleshooting is complete. If any other Pending or Confirmed DTCs are indicated, go to the indicated DTC's troubleshooting. ■

  28. Reconnect all connectors.
  29. Update the ECM/PCM if it does not have the latest software (see ECM/PCM UPDATE ), or substitute a known-good ECM/PCM (see SUBSTITUTING THE ECM/PCM ).
  30. Check for Pending or Confirmed DTCs with the HDS.

    Is DTC P1659 indicated? 

    YES  - Check for poor connections or loose terminals at the ETCS control relay and the ECM/PCM. If the ECM/PCM was updated, substitute a known-good ECM/PCM (see SUBSTITUTING THE ECM/PCM ), then recheck. If the ECM/PCM was substituted, go to step  1.

    NO  - If the ECM/PCM was updated, troubleshooting is complete. If the ECM/PCM was substituted, replace the original ECM/PCM (see ECM/PCM REPLACEMENT ). If any other Pending or Confirmed DTCs are indicated, go to the indicated DTC's troubleshooting. ■

scientia non olet · About LEMON Manuals