DLC Circuit Troubleshooting

If the ECM does not communicate with the HDS, do this troubleshooting procedure.
Check that the MIL circuit is normal, then do this troubleshooting.

Measure voltage between DLC terminal No. 16 and body ground.

Fig 1: Measuring Voltage Between DLC Terminal No. 16 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?
1. YES - Go to step 2.
2. NO - Repair open in the wire between DLC terminal No. 16 and the No. 18 (7.5 A) fuse in the under-hood fuse/relay box.
Measure voltage between DLC terminals No. 4 and No. 16.

Fig 2: Measuring Voltage Between DLC Terminals No. 4 And 16
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?
1. YES - Go to step 3.
2. NO - Repair open in the wire between DLC terminal No. 4 and body ground.
Measure voltage between DLC terminals No. 5 and No. 16.

Fig 3: Measuring Voltage Between DLC Terminals No. 5 And 16
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?
1. YES - Go to step 4.
2. NO - Repair open in the wire between DLC terminal No. 5 and body ground.
Turn the ignition switch ON (II).
Measure voltage between DLC terminals No. 5 and No. 7.

Fig 4: Measuring Voltage Between DLC Terminals No. 5 And 7
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there 8.5 V or more?
1. YES - Go to step 10.
2. NO - Go to step 6.
Turn the ignition switch OFF, and wait for 10 seconds.
Disconnect ECM connector A (32P).
Check for continuity between DLC terminal No. 7 and body ground.

Fig 5: Checking Continuity Between DLC Terminal No. 7 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?
1. YES - Repair short to ground in the wire between DLC terminal No. 7 and the ECM (A21). After repairing the wire, check the DTC with the HDS, and go to the indicated DTC TROUBLESHOOTING .
2. NO - Go to step 9.
Check for continuity between DLC terminal No. 7 and ECM terminal A21.

Fig 6: Checking Continuity Between DLC Terminal No. 7 And ECM Terminal A21
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?
1. YES - Update the ECM if it does not have the latest software, or substitute a known-good ECM; 2000-2001 M/T models (see HOW TO SUBSTITUTE THE ECM FOR TESTING PURPOSES (2000-2001 M/T MODELS) ), 2002-2006 M/T models and CVT model (see ECM UPDATING AND SUBSTITUTION FOR TESTING-2002-2006 M/T MODELS AND CVT MODEL ), then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM (see ECM REPLACEMENT ).
2. NO - Repair open in the wire between DLC terminal No. 7 and the ECM (A21). After repairing the wire, check the DTC with the HDS, and go to the indicated DTC TROUBLESHOOTING .
Turn the ignition switch OFF, and wait for 10 seconds.
Disconnect ECM connector A (32P).
Turn the ignition switch ON (II).
Measure voltage between DLC terminals No. 5 and No. 7.

Fig 7: Measuring Voltage Between DLC Terminals No. 5 And 7
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there 0 V?
1. YES - Update the ECM if it does not have the latest software, or substitute a known-good ECM; 2000-2001 M/T models (see HOW TO SUBSTITUTE THE ECM FOR TESTING PURPOSES (2000-2001 M/T MODELS) ), 2002-2006 M/T models and CVT model (see ECM UPDATING AND SUBSTITUTION FOR TESTING-2002-2006 M/T MODELS AND CVT MODEL ), then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM (see ECM REPLACEMENT ).
2. NO - Repair short to power in the wire between DLC terminal No. 7 and the ECM (A21). After repairing the wire, check for DTCs with the HDS, and go to the indicated DTC TROUBLESHOOTING .