Operation CHARM: Car repair manuals for everyone.
Home >> Mitsubishi Truck >> 2002 >> Montero Sport ES 4WD V6-3.0L SOHC >> Repair and Diagnosis >> Transmission and Drivetrain >> Transmission Control Systems >> Testing and Inspection >> Symptom Related Diagnostic Procedures >> Symptom Diagnosis Charts >> Inspection Procedure 15

Inspection Procedure 15

INSPECTION PROCEDURE 15: Vehicle Shifts Differently with A/C Engaged









CIRCUIT OPERATION
^ When the A/C is turned ON and the dual pressure switch is closed, PCM (terminal number 83) receives battery voltage and then determines the A/C compressor has been signaled to engage.
^ When the A/C compressor is engaged, the PCM increases line pressure and briefly delays shift points to compensate for the additional engine load.

COMMENT
^ The cause is probably a faulty dual pressure switch circuit or a defective PCM.

TROUBLESHOOTING HINTS (The most likely causes for this code to be set:)
^ Malfunction of the dual pressure switch
^ Damaged harness, connector
^ Malfunction of A/C system
^ Malfunction of the PCM

DIAGNOSIS

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





STEP 1. Using scan tool MB991502, check data list item 65: Dual Pressure Switch.

CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.

1. Connect scan tool MB991502 to the data link connector.
2. Start the engine and run at idle.
3. Set scan tool MB991502 to data reading mode for item 65: Dual Pressure Switch.
^ When the A/C is in operation, the scan tool display should be "ON."
^ When the A/C is not in operation, the scan tool display should be "OFF."
4. Turn the ignition switch to "LOCK" (OFF) position.
Q: Is the switch operating properly?
YES: This malfunction is intermittent.
NO: Go to Step 2.





STEP 2. Check connector A-23 at dual pressure switch for damage.
Q: Is the connector in good condition?
YES: Go to Step 3.
NO: Repair or replace it.

STEP 3. Check the power supply voltage at dual pressure switch connector A-23.





1. Disconnect the connector A-23 and measure at the harness side.
2. Start the engine and run at idle.





3. Measure the voltage between terminal 1 and ground.
^ Voltage should be battery positive voltage.
4. Turn the ignition switch to "LOCK" (OFF) position.
Q: Is the voltage normal?
YES: Go to Step 9.
NO: Go to Step 4.

STEP 4. Check the power supply voltage at automatic compressor controller connector C-09 by backprobing.





1. Do not disconnect connector C-09.
2. Start the engine and run at idle.
3. Operate the A/C.





4. Measure the voltage between terminal 2 and ground by backprobing.
^ Voltage should be battery positive voltage.
5. Turn the ignition switch to "LOCK" (OFF) position.
Q: Is the voltage normal?
YES: Go to Step 8.
NO: Go to Step 5.








STEP 5. Check connectors C-09 at automatic compressor controller and C-41 at intermediate connector for damage.
Q: Are the connectors in good condition?
YES: Go to Step 6.
NO: Repair or replace the defective connector(s).








STEP 6. Check harness for short circuit to ground between dual pressure switch connector A-23 terminal 1 and automatic compressor controller connector C-09 terminal 2.
Q: Is the harness wire in good condition?
YES: Go to Step 7.
NO: Repair it.





STEP 7. Using scan tool MB991502, check data list item 65: Dual Pressure Switch.

CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.

1. Connect scan tool MB991502 to the data link connector.
2. Start the engine and run at idle.
3. Set scan tool MB991502 to data reading mode for item 65: Dual Pressure Switch.
^ When the A/C is in operation, the scan tool display should be "ON."
^ When the A/C is not in operation, the scan tool display should be "OFF."
4. Turn the ignition switch to "LOCK" (OFF) position.
Q: Is the switch operating properly?
YES: This malfunction is intermittent.
NO: Check the air conditioning system.








STEP 8. Check connectors C-09 at automatic compressor controller and C-41 at intermediate connector for damage.
Q: Are the connectors in good condition?
YES: Repair harness open circuit between automatic compressor controller connector C-09 terminal 2 and dual pressure switch connector A-23 terminal 1.
NO: Repair or replace the defective connector(s).

STEP 9. Check the switch output voltage at PCM connector C-91 by backprobing.





1. Do not disconnect connector C-91.
2. Start the engine and run at idle.
3. Operate the A/C.





4. Measure the voltage between terminal 83 and ground by backprobing.
^ When the A/C is in operation, the voltage should be battery positive voltage.
^ When the A/C is not in operation, the voltage should be 0.5 volt or less.
5. Turn the ignition switch to "LOCK" (OFF) position.
Q: Is the voltage normal?
YES: Go to Step 15.
NO: Go to Step 10.








STEP 10. Check connectors C-91 at PCM, A-25 at A/C refrigerant temperature switch and A-89 at intermediate connector for damage.
Q: Are the connectors in good condition?
YES: Go to Step 11.
NO: Repair or replace the defective connector(s).








STEP 11. Check harness for short circuit to ground or open circuit between dual pressure switch connector A-23 terminal 2 and PCM connector C-91 terminal 83.
Q: Is the harness wire in good condition?
YES: Go to Step 12.
NO: Repair it.

STEP 12. Check the dual pressure switch.
Q: Is the switch operating properly?
YES: Go to Step 13.
NO: Replace the dual pressure switch.





STEP 13. Check the A/C refrigerant temperature switch.
Check that there is continuity between the refrigerant temperature switch terminals.
Q: Is the continuity normal?
YES: Go to Step 14.
NO: Replace the compressor assembly.





STEP 14. Using scan tool MB991502, check data list item 65: Dual Pressure Switch.

CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.

1. Connect scan tool MB991502 to the data link connector.
2. Start the engine and run at idle.
3. Set scan tool MB991502 to data reading mode for item 65: Dual Pressure Switch.
^ When the A/C is in operation, the scan tool display should be "ON."
^ When the A/C is not in operation, the scan tool display should be "OFF."
4. Turn the ignition switch to "LOCK" (OFF) position.
Q: Is the switch operating properly?
YES: This malfunction is intermittent.
NO: Replace the PCM.





STEP 15. Check connector C-91 at PCM for damage.
Q: Is the connector in good condition?
YES: Go to Step 14.
NO: Repair or replace it.



pro multis · About Operation CHARM