DTC 54

DTC 54: A/T Control Relay System

CIRCUIT OPERATION
^ A/T control relay (terminal 4) receives the battery positive voltage through a dedicated 20 amp fuse.
^ When the ignition switch is turned to the "ON" position, the PCM (terminal 50) receives battery voltage from the ignition switch. The PCM (terminal 50) applies voltage to energize the A/T control relay (terminal 3). With the A/T control relay energized, system voltage is applied to the PCM (terminals 77 and 89).

DTC SET CONDITIONS
If the A/T control relay voltage is less than 7 volts at the PCM (terminals 77 and 89) when the ignition switch is in the "ON" position DTC 54 will be set. The transaxle is locked into the 3rd gear as a fail-safe measure, and the "N" range light flashes once per second.

TROUBLESHOOTING HINTS
(The most likely causes for this code to be set are:)
^ Malfunction of the A/T control relay
^ Damaged harness or connector
^ Malfunction of the PCM

DIAGNOSIS

Required Special Tool:
^ MB991502: Scan Tool (MUT-II)

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.
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.
NO: Go to Step 2.

STEP 2. Check the A/T control relay.





1. Remove the A/T control relay from the engine component relay box connector B-11X.





2. Using jumper wires, connect terminal 3 to the positive battery terminal, and terminal 2 to the negative battery terminal.
3. Measure the resistance between terminals 1 and 4 of the A/T control relay.
^ The resistance should measure less than 2 ohms.
^ Disconnect the jumper wires. The resistance between terminals 1 and 4 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.

STEP 3. Check A/T control relay socket B-11X in the engine compartment relay box for loose, corroded or damaged terminals, or terminals pushed back in the socket.





Q: Is the relay connector in good condition?
YES: Go to Step 4.
NO: Repair or replace the damaged components.

STEP 4. Measure the supply voltage at A/T control relay connector B-11X in the engine component relay box.





1. Disconnect the A/T control relay.





2. Measure the voltage between terminal 1 and ground.
^ The measured voltage should equal battery positive voltage.
Q: Is the measured voltage equal to battery positive voltage?
YES: Go to Step 7.
NO: Go to Step 5.

STEP 5. Check intermediate connector A-13 for loose, corroded or damaged terminals, or terminals pushed back in the connector.





Q: Are the connector and terminals in good condition?
YES: Go to Step 6.
NO: Repair or replace the damaged components.

STEP 6. Check the harness for open circuit or short circuit to ground between A/T control relay connector B-11X terminal 1 in the engine component relay box and battery.





Q: Is the harness wire in good condition?
YES: Go to Step 18.
NO: Repair or replace the harness wire.

STEP 7. Measure the supply voltage at A/T control relay connector B-11X in the engine component relay box.





1. Disconnect the A/T control relay.
2. Turn the ignition switch to the "ON" position.





3. Measure the voltage between terminal 2 and ground.
^ The measured 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: Go to Step 10.
NO: Go to Step 8.

STEP 8. Check intermediate connector C-123 and junction block connector C-210 for loose, corroded or damaged terminals, or terminals pushed back in the connector.








Q: Are the connectors in good condition?
YES: Go to Step 9.
NO: Repair or replace the damaged components.

STEP 9. Check the harness for open circuit or short circuit to ground between A/T control relay connector B-11X terminal 2 in the engine component relay box and junction block connector C-210 terminal 12.








Q: Is the harness wire in good condition?
YES: Go to Step 18.
NO: Repair or replace the harness wire.

STEP 10. Measure the supply voltage at PCM connector C118 by backprobing.





1. Do not disconnect connector C-118.





2. Measure the voltage between terminal 50 and ground by backprobing.
^ The measured voltage should equal battery positive voltage.
3. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Does the measured voltage equal battery positive voltage?
YES: Go to Step 14.
NO: Go to Step 11.

STEP 11. Check PCM connector C-118 for loose, corroded or damaged terminals, or terminals pushed back in the connector.





Q: Are the connector and terminals in good condition?
YES: Go to Step 12.
NO: Repair or replace the damaged components.

STEP 12. Check harness for open circuit or damage between A/T control relay connector B-11X terminal 3 in the engine component relay box and PCM connector C-118 terminal 50.








Q: Is the harness wire in good condition?
YES: Go to Step 13.
NO: Repair or replace the harness wire.

STEP 13. Check harness for short circuit to ground between A/T control relay connector B-11X terminal 3 in the engine component relay box and PCM connector C-118 terminal 50.








Q: Is the harness wire in good condition?
YES: Go to Step 14.
NO: Repair or replace the harness wire.

STEP 14. Measure the A/T control relay output voltage at PCM connector C-116 by backprobing.





1. Do not disconnect connector C-116.
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.





4. Measure the voltage between terminal 89 and ground by backprobing.
^ The measured voltage should equal battery positive voltage.
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 18.
NO: Go to Step 15.

STEP 15. Check PCM connector C-116 for loose, corroded or damaged terminals, or terminals pushed back in the connector.





Q: Are the connector and terminals in good condition?
YES: Go to Step 16.
NO: Repair or replace the damaged components.

STEP 16. Check harness for open circuit or damage between A/T control relay connector B-11X (terminal 4) in the engine component relay box and PCM connector C-116 (terminals 77 and 89).








Q: Is the harness wire in good condition?
YES: Go to Step 17.
NO: Repair or replace the harness wire.

STEP 17. Check harness for short circuit to ground between A/T control relay connector B-11X (terminal 4) in the engine component relay box and PCM connector C-116 (terminals 77 and 89).








Q: Is the harness wire in good condition?
YES: Go to Step 18.
NO: Repair or replace the harness wire.

STEP 18. 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.
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 that this malfunction is intermittent.
NO: Replace the PCM.