DLC Circuit Troubleshooting

NOTE:

If the ECM/PCM does not communicate with the HDS or I/M test equipment, do this troubleshooting procedure.
Check that 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 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. 9 BACK UP (10 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
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 (G451).
Measure voltage between DLC terminals No. 5 and No. 16.

Fig 3: Measuring Voltage Between DLC Terminals
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 the ECM/PCM (E3) and DLC terminal No. 5.
Turn the ignition switch ON (II).
Measure voltage between DLC terminals No. 5 and No. 7.

Fig 4: Measuring Voltage Between DLC Terminals
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there 8.5 V or more?
1. YES- Go to step 11.
2. NO- Go to step 6.
Turn the ignition switch OFF.
Jump the SCS line with the HDS.
Disconnect ECM/PCM connector E (31P).
Check for continuity between DLC terminal No. 7 and body ground.

Fig 5: Checking For Continuity Between DLC Terminal 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/PCM (E23). After repairing the wire, check for a DTC with the HDS, then go to the DTC TROUBLESHOOTING .
2. NO- Go to step 10.
Check for continuity between DLC terminal No. 7 and ECM/PCM terminal E23.

Fig 6: Checking Continuity Between DLC Terminal And ECM/PCM Terminal E23
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?
1. YES- Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM (see ECM/PCM UPDATING AND SUBSTITUTION FOR TESTING ), then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM (see MAP SENSOR REPLACEMENT ).
2. NO- Repair open in the wire between DLC terminal No. 7 and the ECM/PCM (E23). After repairing the wire, check for a DTC with the HDS, then go to the DTC TROUBLESHOOTING .
Turn the ignition switch OFF.
Jump the SCS line with the HDS.
Disconnect ECM/PCM connector E (31P).
Turn the ignition switch ON (II).
Measure voltage between DLC terminals No. 5 and No. 7.

Fig 7: Measuring Voltage Between DLC Terminals
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there 0 V?
1. YES- Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM (see ECM/PCM UPDATING AND SUBSTITUTION FOR TESTING ), then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM (see MAP SENSOR REPLACEMENT ).
2. NO- Repair short to power in the wire between DLC terminal No. 7 and the ECM/PCM (E23). After repairing the wire, check for a DTC with the HDS, then go to the DTC TROUBLESHOOTING .