DLC Circuit Troubleshooting

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2005 Honda S2000, 2004 Honda S2000, 2003 Honda S2000, 2002 Honda S2000, and 2001 Honda S2000. However, it is still accessible from the selected car via links, so may be relevant.

If the ECM does not communicate with a scan tool, the HDS, or I/M test equipment, do this troubleshooting procedure.

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. 8 and the ACGS (15 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 No. 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. 8 and body ground (G401).
Measure voltage between DLC terminals No. 5 and No. 16.

Fig 3: Measuring Voltage Between DLC Terminals No. 5 And No. 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. 8 and body ground (G101).
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 No. 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.
Disconnect ECM connector A (32P). Make sure the scan tool or the HDS is disconnected from the DLC.
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. 15 and the ECM (A21). After repairing the wire, check for DTCs with a scan tool or the HDS, and go to the indicated DTC's troubleshooting .
2. NO - Go to step 9.
Check for continuity between DLC terminal No. 15 and ECM terminal A21.

Fig 6: Checking Continuity Between DLC Terminal No. 15 And ECM Terminal A21
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?
1. YES - Substitute a known-good ECM (see HOW TO SUBSTITUTE THE ECM FOR TESTING PURPOSES ) and recheck. If the symptom/indication goes away, 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 for DTCs with a scan tool or the HDS, and go to the indicated DTC's troubleshooting.
Turn the ignition switch OFF.
Disconnect ECM connector A (32P). Make sure a scan tool or the HDS is disconnected from the DLC.
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 No. 7
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there 0 V?
1. YES - Substitute a known-good ECM (see HOW TO SUBSTITUTE THE ECM FOR TESTING PURPOSES ) and recheck. If the symptom/indication goes away, replace the original ECM (see ECM REPLACEMENT ).
2. NO - Repair short to power in the wire between the DLC terminal No. 7 and the ECM (A21). After repairing the wire, check for DTCs with a scan tool or the HDS, and go to the indicated DTC's troubleshooting.