Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
2004 Honda S2000 L4-2.2LFACTORY OEM SERVICE PROCEDURE
Data Link Connector: Testing and Inspection
DLC Circuit Troubleshooting
If the ECM does not communicate with a scan tool, HDS or 1/M test equipment, do this troubleshooting procedure.
1. Measure voltage between DLC terminal No. 16 and body ground.
Is there battery voltage?
YES - Go to step 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.
2. Measure voltage between DLC terminals No. 4 and No.16.
Is there battery voltage?
YES - Go to step 3.
NO - Repair open in the wire between DLC terminal No. 8 and body ground (G401).
3. Measure voltage between DLC terminals No. 5 and No.16.
Is there battery voltage?
YES - Go to step 4.
NO - Repair open in the wire between DLC terminal No. 8 and body ground (G101).
4. Turn the ignition switch ON (II).
5. Measure voltage between DLC terminals No. 5 and No. 7.
Is there 8.5 V or more?
YES - Go to step 10.
NO - Go to step 6.
6. Turn the ignition switch OFF.
7. Disconnect ECM connector A (32P). Make sure a scan tool or the HDS is disconnected from the DLC.
8. Check for continuity between DLC terminal No. 7 and body ground.
Is there continuity?
YES - Repair short to ground in the wire between DLC terminal No. 15 and the ECM (A21). After repairing the wire, check the DTC with a scan tool/HDS and go to the indicated DTC's troubleshooting.
NO - Go to step 9.
9. Check for continuity between DLC terminal No. 15 and ECM terminal A21.
Is there continuity?
YES - Substitute a known-good ECM and recheck. If the symptom/indication goes away, replace the original ECM.
NO - Repair open in the wire between DLC terminal No. 7 and the ECM (A21). After repairing the wire, check the DTC with a scan tool/HDS and go to the indicated DTC's troubleshooting.
10. Turn the ignition switch OFF.
11. Disconnect ECM connector A (32P). Make sure a scan tool or HDS is disconnected from the DLC.
12. Turn the ignition switch ON (II).
13. Measure voltage between DLC terminals No. 5 and No. 7.
Is there 0 V?
YES - Substitute a known-good ECM and recheck. If the symptom/indication goes away, replace the original ECM.
NO - Repair short to power in the wire between the DLC terminal No. 7 and the ECM (A21). After repairing the wire, check the DTC with a scan tool/HDS and go to the indicated DTC's troubleshooting.
If the ECM does not communicate with a scan tool, HDS or 1/M test equipment, do this troubleshooting procedure.
1. Measure voltage between DLC terminal No. 16 and body ground.
Is there battery voltage?
YES - Go to step 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.
2. Measure voltage between DLC terminals No. 4 and No.16.
Is there battery voltage?
YES - Go to step 3.
NO - Repair open in the wire between DLC terminal No. 8 and body ground (G401).
3. Measure voltage between DLC terminals No. 5 and No.16.
Is there battery voltage?
YES - Go to step 4.
NO - Repair open in the wire between DLC terminal No. 8 and body ground (G101).
4. Turn the ignition switch ON (II).
5. Measure voltage between DLC terminals No. 5 and No. 7.
Is there 8.5 V or more?
YES - Go to step 10.
NO - Go to step 6.
6. Turn the ignition switch OFF.
7. Disconnect ECM connector A (32P). Make sure a scan tool or the HDS is disconnected from the DLC.
8. Check for continuity between DLC terminal No. 7 and body ground.
Is there continuity?
YES - Repair short to ground in the wire between DLC terminal No. 15 and the ECM (A21). After repairing the wire, check the DTC with a scan tool/HDS and go to the indicated DTC's troubleshooting.
NO - Go to step 9.
9. Check for continuity between DLC terminal No. 15 and ECM terminal A21.
Is there continuity?
YES - Substitute a known-good ECM and recheck. If the symptom/indication goes away, replace the original ECM.
NO - Repair open in the wire between DLC terminal No. 7 and the ECM (A21). After repairing the wire, check the DTC with a scan tool/HDS and go to the indicated DTC's troubleshooting.
10. Turn the ignition switch OFF.
11. Disconnect ECM connector A (32P). Make sure a scan tool or HDS is disconnected from the DLC.
12. Turn the ignition switch ON (II).
13. Measure voltage between DLC terminals No. 5 and No. 7.
Is there 0 V?
YES - Substitute a known-good ECM and recheck. If the symptom/indication goes away, replace the original ECM.
NO - Repair short to power in the wire between the DLC terminal No. 7 and the ECM (A21). After repairing the wire, check the DTC with a scan tool/HDS and go to the indicated DTC's troubleshooting.
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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