DLC Circuit Troubleshooting

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

1. Turn the ignition switch ON (II).
2. Measure voltage between data link connector (DLC) terminal No. 16 and body ground.
   Fig 1: Measuring Voltage Between DLC Terminal No. 16 & Body Ground

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   Is there battery voltage? 

   1. YES  -Go to step 3.
   2. NO  -Repair open in the wire between DLC terminal No. 16 and the ACGS (15A) fuse in the under-hood fuse/relay box.
3. Measure voltage between DLC terminals No. 4 and No. 16.
   Fig 2: Measuring Voltage Between DLC Terminals No. 4 & No. 16

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   Is there battery voltage? 

   1. YES  -Go to step 4.
   2. NO  -Repair open in the wire between DLC terminal No. 4 and body ground.
4. Measure voltage between DLC terminals No. 5 and No. 16.
   Fig 3: Measuring Voltage Between DLC Terminals No. 5 & No. 16

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   Is there battery voltage? 

   1. YES  -Go to step 5.
   2. NO  -Repair open in the wire between DLC terminal No. 5 and body ground.
5. Measure voltage between DLC terminals No. 5 and No. 7.
   Fig 4: Measuring Voltage Between DLC Terminals No. 5 & No. 7

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   Is there 8.5 V or more? 

   1. YES  -Go to step  10.
   2. NO  -Go to step 6.
6. Turn the ignition switch OFF.
7. Disconnect the PCM connector A (32P).
8. Check for continuity between DLC terminal No. 7 and body ground.
   Fig 5: Checking For Continuity Between DLC Terminal No. 7 & Body Ground

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   Is there continuity? 

   1. YES  -Repair short to ground in the wire between DLC terminal No. 7 and the PCM (A21).
   2. NO  -Go to step 9.
9. Check for continuity between DLC terminal No. 7 and PCM terminal A21.
   Fig 6: Checking For Continuity Between DLC Terminal No. 7 & PCM Terminal A21

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   Is there continuity? 

   1. YES  -Substitute a known-good PCM and recheck (see HOW TO SUBSTITUTE THE PCM FOR TESTING ). If the symptom/indication goes away, replace the original PCM.
   2. NO  -Repair open in the wire between DLC terminal No. 7 and the PCM (A21).
10. Turn the ignition switch OFF.
11. Disconnect the PCM connector A (32P).
12. Turn the ignition switch ON (II).
13. Measure voltage between DLC terminals No. 5 and No. 7.
    Fig 7: Measuring Voltage Between DLC Terminals No. 5 & No. 7

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    Is there 0V? 

    1. YES  -Substitute a known-good PCM and recheck (see HOW TO SUBSTITUTE THE PCM FOR TESTING ). If the symptom/indication goes away, replace the original PCM.
    2. NO  -Repair short to power in the wire between DLC terminal No. 7 and PCM (A21).