DTC : 54 Control Relay system: Diagnosis

Required Special Tool: 

• MB991502: Scan Tool (MUT-II)

1. STEP 1. Using scan tool MB991502, check data list item 54: A/T Control Relay Output Voltage. 
   CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.
   1. Connect scan tool MB991502 to the data link connector.
      Fig 1: Connecting Scan Tool MB991502 To Data Link Connector

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   2. Turn the ignition switch to the "ON" position.
   3. Set scan tool MB991502 to data-reading mode for item 54, A/T Control Relay Output Voltage.
      • The voltage should equal battery positive voltage.
   4. Turn the ignition switch to the "LOCK" (OFF) position.

   Q: Is the measured voltage equal battery positive voltage? 

   YES:  It can be assumed that this malfunction is intermittent. Refer to How to Use Troubleshooting/Inspection Service Points - HOW TO COPE WITH INTERMITTENT MALFUNCTIONS .

   NO:  Go to Step 2.

2. STEP 2. Check the A/T control relay. 
   1. Remove the A/T control relay (A/T control relay connector C-97).
      Fig 2: Locating A/T Control Relay Connector C 97 & Terminal Identification

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   2. Using jumper wires, connect terminal 2 to the negative battery terminal, and terminal 4 to the positive battery terminal.
   3. Measure the resistance between terminal 1 and 3 of the A/T control relay.
      • The resistance should measure less than 2 ohms.
        Fig 3: Measuring Resistance Between Terminal 1 And 3 Of The A/T Control Relay

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      • Disconnect the jumper wires. The resistance between terminals 1 and 3 should measure over limits (open circuit).

   Q: Does the resistance measure less than 2 ohms when the relay is energized, and open circuit when the relay is de-energized? 

   YES:  Go to Step 3.

   NO:  Replace the A/T control relay.

3. STEP 3. Check A/T control relay connector C-97 for loose, corroded or damaged terminals, or terminals pushed back in the connector. 
   Fig 4: Locating A/T Control Relay Connector C 97 & Terminal Identification

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   Q: Are the connector and terminals in good condition? 

   YES:  Go to Step 4.

   NO:  Repair or replace the damaged components. Refer to HARNESS CONNECTOR INSPECTION .

4. STEP 4. Measure the supply voltage at A/T control relay connector C-97. 
   1. Disconnect the A/T control relay and measure at the harness side.
      Fig 5: Locating A/T Control Relay Connector C 97 & Terminal Identification

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   2. Measure the voltage between terminal 1 and ground.
   • The measured voltage should equal battery positive voltage.
     Fig 6: Measuring Voltage Between Connector C 97 Terminal 1 And Ground

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   Q: Is the measured voltage equal to battery positive voltage? 

   YES:  Go to Step  7.

   NO:  Go to Step 5.

5. STEP 5. Check junction block connectors D-09 and D-02 for loose, corroded or damaged terminals, or terminals pushed back in the connector. 
   Fig 7: Locating Junction Block Connector D 02 & Terminal Identification

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   Fig 8: Locating Junction Block Connector D 09 & Terminal Identification

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   Q: Are the connectors and terminals in good condition? 

   YES:  Go to Step 6.

   NO:  Repair or replace the damaged components. Refer to HARNESS CONNECTOR INSPECTION .

6. STEP 6. Check the harness for open circuit or short circuit to ground between A/T control relay connector C-97 terminal 1 and fusible link. 
   Fig 9: Locating A/T Control Relay Connector C 97 & Terminal Identification

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   Q: Is the harness wire in good condition? 

   YES:  Go to Step  17.

   NO:  Repair or replace the harness wire.

7. STEP 7. Measure the resistance at A/T control relay connector C-97. 
   1. Disconnect the A/T control relay and measure at the harness side.
      Fig 10: Locating A/T Control Relay Connector C 97 & Terminal Identification

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   2. Measure the resistance between terminal 2 and ground.
      • The resistance should measure less than 2 ohms.
      Fig 11: Measuring Resistance Between C 97 Connector Terminal 2 And Ground

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   Q: Is the measured resistance less than 2 ohms? 

   YES:  Go to Step  9.

   NO:  Go to Step 8.

8. STEP 8. Check the harness for open circuit or damage between A/T control relay connector C-97 terminal 2 and ground. 
   Fig 12: Locating A/T Control Relay Connector C 97 & Terminal Identification

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   Q: Is the harness wire in good condition? 

   YES:  Go to Step  17.

   NO:  Repair or replace the harness wire.

9. STEP 9. Measure the control voltage to A/T control relay connector C-97. 
   1. Disconnect the A/T control relay and measure at the connector side.
      Fig 13: Locating A/T Control Relay Connector C 97 & Terminal Identification

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   2. Turn the ignition switch to the "ON" position.
   3. Measure the voltage between terminal 4 and ground.
      • The measured voltage should equal battery positive voltage.
      Fig 14: Measuring Voltage Between Connector C 97 Terminal 4 And Ground

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   4. Turn the ignition switch to the "LOCK" (OFF) position.

   Q: Is the measured voltage equal to battery positive voltage? 

   YES:  Go to Step  14.

   NO:  Go to Step 10.

10. STEP 10. Measure the supply voltage at PCM connector C-90 by backprobing. 
    1. Do not disconnect connector C-90.
       Fig 15: Locating PCM Connector C 90 & Terminal Identification

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    2. Turn the ignition switch to the "ON" position.
    3. Measure the voltage between terminal 50 and ground by backprobing.
       • The measured voltage should equal battery positive voltage.
       Fig 16: Measuring Voltage Between Connector C 90 Terminal 50 And Ground By Backprobing

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    4. Turn the ignition switch to the "LOCK" (OFF) position.

    Q: Is the measured voltage equal to battery positive voltage? 

    YES:  Go to Step 11.

    NO:  Go to Step  13.

11. STEP 11. Check intermediate connector C-85 and PCM connector C-90 for loose, corroded or damaged terminals, or terminals pushed back in the connector. 
    Fig 17: Locating Intermediate Connector C 85 & Terminal Identification

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    Fig 18: Locating PCM Connector C 90 & Terminal Identification

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    Q: Are the connectors and terminals in good condition? 

    YES:  Go to Step 12.

    NO:  Repair or replace the damaged components. Refer to HARNESS CONNECTOR INSPECTION .

12. STEP 12. Check the harness for open circuit or damage between PCM connector C-90 terminal 50 and A/T control relay connector C-97 terminal 4. 
    Fig 19: Locating PCM Connector C 90 & Terminal Identification

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    Fig 20: Locating A/T Control Relay Connector C 97 & Terminal Identification

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    Q: Is the harness wire in good condition? 

    YES:  Go to Step  17.

    NO:  Repair or replace the harness wire.

13. STEP 13. Check for a short circuit to ground between PCM connector C-90 terminal 50 and A/T control relay connector C-97 terminal 4. 
    Fig 21: Locating PCM Connector C 90 & Terminal Identification

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    Fig 22: Locating A/T Control Relay Connector C 97 & Terminal Identification

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    Q: Is the harness wire in good condition? 

    YES:  Go to Step  17.

    NO:  Repair or replace the harness wire.

14. STEP 14. Measure the A/T control relay output voltage at PCM connector C-91 by backprobing. 
    1. Do not disconnect connector C-91.
       Fig 23: Locating PCM Connector C 91 & Terminal Identification

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    2. Turn the ignition switch to the "ON" position.
    3. Measure the voltage between terminal 77 and ground by backprobing.
       • The measured voltage should equal battery positive voltage.
       Fig 24: Measuring Voltage Between Connector C 91 Terminal 77 And Ground By Backprobing

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    4. Measure the voltage between terminal 89 and ground by backprobing.
       • The measured voltage should equal battery positive voltage.
       Fig 25: Measuring Voltage Between Connector C 91 Terminal 89 And Ground By Backprobing

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    5. Turn the ignition switch to the "LOCK" (OFF) position.

    Q: Is the measured voltage equal to battery positive voltage between terminal 77 and ground, and between terminal 89 and ground? 

    YES:  Go to Step  17.

    NO:  Go to Step 15.

15. STEP 15. Check intermediate connector C-41 and PCM connector C-91 for loose, corroded or damaged terminals, or terminals pushed back in the connector. 
    Fig 26: Locating Intermediate Connector C 41 & Terminal Identification

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    Fig 27: Locating PCM Connector C 91 & Terminal Identification

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    Q: Are the connectors and terminals in good condition? 

    YES:  Go to Step 16.

    NO:  Repair or replace the damaged components. Refer to HARNESS CONNECTOR INSPECTION .

16. STEP 16. Check harness for open circuit or short circuit to ground between PCM connector C-91 terminals 77, 89 and A/T control relay connector C-97 terminal 3. 
    Fig 28: Locating PCM Connector C 91 & Terminal Identification

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    Fig 29: Locating A/T Control Relay Connector C 97 & Terminal Identification

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    Q: Is the harness wire in good condition? 

    YES:  Go to Step 17.

    NO:  Repair or replace the harness wire.

17. STEP 17. Using scan tool MB991502, check data list item 54: A/T control relay output Voltage. 
    CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.
    1. Connect scan tool MB991502 to the data link connector.
       Fig 30: Connecting Scan Tool MB991502 To Data Link Connector

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    2. Turn the ignition switch to the "ON" position.
    3. Set scan tool MB991502 to data-reading mode for item 54, A/T Control Relay Output Voltage.
       • The voltage should equal battery positive voltage.
    4. Turn the ignition switch to the "LOCK" (OFF) position.

    Q: Is the measured voltage equal to battery positive voltage? 

    YES:  It can be assumed that this malfunction is intermittent. Refer to How to Use Troubleshooting/Inspection Service Points - HOW TO COPE WITH INTERMITTENT MALFUNCTIONS .

    NO:  Replace the PCM.