Short-Circuit To Ground Or Open-Circuit

SPECIAL TOOLS
Test box tool No. 981 3190, or equivalent
Volvo scan tool No. 998 8686, or equivalent

SHORT-CIRCUIT TO GROUND OR OPEN-CIRCUIT
1. Other diagnostic trouble codes (DTCs)
- Read off OTHER DTCs.
- Is diagnostic trouble code (DTC) AT-123 stored?
YES: Proceed to step 2
NO: Proceed to step 3
2. Fault-tracing information
- Fault-trace according to DTC. AT-123 System Pressure Solenoid STH
- Then continue with step 35





3. Checking solenoid STH
- Preparation:
Ignition ON
Select scrolling values
Read off current in solenoid circuit
Depress accelerator pedal (AP) slowly
- The current should decrease as the accelerator pedal (AP) is depressed.
- If reading is OK:
Proceed to step 37
- If reading is incorrect:
Proceed to step 4





4. Checking power ground
- Preparation:
Ignition OFF
- Connect the test box and check ground terminals, refer to Connecting The Test Box. Connecting the Box
- Check the power ground carefully.
- Is the reading OK?
YES: Proceed to step 6
NO: Proceed to step 5
5. Fault-tracing information
- The cause of the diagnostic trouble code (DTC) has been a poor power ground.
- Then continue with step 35





6. Checking voltage drop over signal ground and power ground
- Preparation:
Ignition OFF
Connect transmission control module (TCM)
Ignition ON
Turn on as many power consuming items as possible.
- Connect a voltmeter between #20 (#A20) and #29 (#A29) on the test box.
- The voltmeter should read less than 0.6 volts
- If reading is OK:
Proceed to step 8
- If reading is incorrect:
Proceed to step 7





7. Checking for open circuit, contact resistance and oxidation
- Preparation:
Ignition OFF
- Check ground terminals 31/32 and 31/33, cables between ground terminal and TCM and TCM connector for:
An open-circuit according to step of checking for permanent faults. Checking For Permanent Faults
Contact resistance and oxidation according to step 5 of checking for permanent faults. Checking For Permanent Faults
- Then continue with step 35





8. Checking resistance in solenoid STH circuit
- Preparation:
Ignition OFF
Disconnect TCM
- Connect an ohmmeter between #22 (#A22) and #23 (#A23) on the test box.
- The ohmmeter should read 2-6 Ohms
- If reading is OK:
Proceed to step 18
- If reading is incorrect:
Proceed to step 9





9. Checking resistance in solenoid STH circuit in the transmission
- Preparation:
Ignition OFF
Remove the air cleaner (ACL) housing to access the transmission connector
Disconnect the transmission connector.
- Connect an ohmmeter between the-transmission connector terminals 24 and 25 (transmission side).
- The ohmmeter should read 2-6 Ohms
- If reading is OK:
Proceed to step 13
- If reading is incorrect:
Proceed to step 10





10. Checking resistance in solenoid STH
- Preparation:
Ignition OFF
Open the control system according to steps 1 through 14 of Open Control System. Service and Repair
- Disconnect solenoid STH.
- Connect ohmmeter between the pins in the solenoid connector.
- The ohmmeter should read 2-6 Ohms
- If reading is OK:
Proceed to step 11
- If reading is incorrect:
Proceed to step 12





11. Checking for an open-circuit
- Check cables between solenoid STH and transmission connector terminal 24 and 25 for an open-circuit according to step 2 of checking for permanent faults. Checking For Permanent Faults
- Then continue with step 35





12. Replacing component
- Preparation:
Ignition OFF
- Replace transmission control system, refer to Replacement. Service and Repair
- Then continue with step 35





13. Checking resistance in the control signal cable
- Preparation:
Ignition OFF
Disconnect transmission connector
- Connect an ohmmeter between the transmission connector terminal 24 TCM side and #22 (#A22) on the test box.
- The ohmmeter should read approx. 0 Ohms
- If reading is OK:
Proceed to step 15
- If reading is incorrect:
Proceed to step 14





14. Checking for an open-circuit
- Check cable between transmission connector terminal 24 and transmission control module (TCM) #A22 for an open-circuit according to step 2 of checking for permanent faults. Checking For Permanent Faults
- Then continue with step 35





15. Checking signal cable resistance
- Preparation:
Ignition OFF
Disconnect transmission connector
- Connect an ohmmeter between the transmission connector terminal 25 (transmission control module (TCM) side) and #23 (#A23) on the test box.
- The ohmmeter should read approx. 0 Ohms
- If reading is OK:
Proceed to step 16
- If reading is incorrect:
Proceed to step 17





16. Checking for loose connections, contact resistance and oxidation
- Preparation:
Ignition OFF
- The DTC was caused by poor contact in the TCM or transmission connectors.
- Check the connectors for:
Loose connections and remedy in according to step 5 of checking for intermittent faults. Checking For Intermittent Faults
Contact resistance and oxidation according to step 5 of checking for permanent faults. Checking For Permanent Faults
- Then continue with step 35





17. Checking for an open-circuit
- Check cable between transmission connector terminal 25 and transmission control module (TCM) #A23 for an open-circuit according to step 2 of checking for permanent faults. Checking For Permanent Faults
- Then continue with step 35





18. Checking solenoid STH circuit for short-circuit to ground
- Preparation:
Ignition OFF
TCM disconnected.
- Connect an ohmmeter between #22 (#A22) on the test box and the transmission housing.
- The ohmmeter should read infinite resistance
- If reading is OK:
Proceed to step 26
- If reading is incorrect:
Proceed to step 19





19. Checking solenoid STH circuit in the transmission for a short-circuit to ground
- Preparation:
Ignition OFF
Remove the air cleaner housing to access the transmission connector
Disconnect the transmission connector
- Connect an ohmmeter between the transmission connector terminal 24 (transmission side) and the transmission housing.
- The ohmmeter should read infinite resistance
- If reading is OK:
Proceed to step 23
- If reading is incorrect:
Proceed to step 20





20. Checking solenoid STH for resistance to ground
- Preparation:
Ignition OFF.
Open the control system according to 1 through 14 of Open Control System. Service and Repair
- Disconnect solenoid STH.
- Connect an ohmmeter between one of the pins in the solenoid connector and the transmission housing.
- The ohmmeter should read infinite resistance
- If reading is OK:
Proceed to step 21
- If reading is incorrect:
Proceed to step 22





21. Checking for a short-circuit
- Check cables between solenoid STH and transmission connector terminals 24 and 25 for a short-circuit to ground according to step 3 of checking for permanent faults. Checking For Permanent Faults
- Then continue with step 35





22. Replacing component
- Preparation:
Ignition OFF
- Replace transmission control system, refer to Replacement.Service and Repair
- Then continue with step 35

23. 23. Checking signal cable resistance to ground
Preparation:
Ignition OFF.
TCM disconnected.
Disconnect transmission connector.
- Connect an ohmmeter between #23 (#A23) on the test box and the transmission housing.
- The ohmmeter should read infinite resistance
- If reading is OK:
Proceed to step 24
- If reading is incorrect:
Proceed to step 25





24. Checking for a short-circuit




- Check cable between transmission connector terminal 25 and transmission control module (TCM) #A23 for a short-circuit to ground according to step 3 of checking for permanent faults. Checking For Permanent Faults
- Then continue with step 35





25. Checking for a short-circuit
- Check cable between transmission connector terminal 25 and transmission control module (TCM) #A23 for a short-circuit to ground according to step 3 of checking for permanent faults. Checking For Permanent Faults
- Then continue with step 35





26. Checking the control signal cable for a short-circuit to supply voltage
- Preparation:
Ignition OFF.
Test box connected
Connect transmission control module (TCM)
Ignition ON.
- Connect a voltmeter between #22 (#A22) and #29 (#A29) on the test box.
- The voltmeter should read 0-6 volts
- If reading is OK:
Proceed to step 28
- If reading is incorrect:
Proceed to step 27





27. Checking for a short-circuit
- Check cable between solenoid STH and transmission control module (TCM) #A22 for a short-circuit to supply voltage according to step 4 of checking for permanent faults. Checking For Permanent Faults
- Then continue with step 32





28. Checking signal cable for short-circuit to supply voltage
- Preparation:
Ignition ON.
- Connect a voltmeter between #23 (#A23) and #29 (#A29) on the test box.
- The voltmeter should read 0-2 volts
- If reading is OK:
Proceed to step 29
- If reading is incorrect:
Proceed to step 31





29. Checking the transmission control module

NOTE: The TCM can malfunction if there has been a short-circuit to supply voltage in the solenoid STH circuit.

- Check the transmission control module (TCM) as follows:
- Preparation:
Ignition OFF
Reconnect connectors, reinstall components etc
Ignition ON
Select scrolling values
Read off current in solenoid circuit
Depress accelerator pedal (AP) slowly
- The current should decrease as the accelerator pedal (AP) is depressed.
- If reading is OK:
Proceed to step 30
- If reading is incorrect:
Proceed to step 34





30. Checking for contact resistance and oxidation.
- Preparation:
Ignition off
- The DTC was caused by poor contact in the TCM or transmission connectors
- Check connector for contact resistance and oxidation and remedy according to step 5 of checking for permanent faults. Checking For Permanent Faults
- Then continue with step 35






31. Checking for a short-circuit
- Check cable between solenoid STH and TCM #A23 for a short-circuit to supply voltage according to step 4 of checking for permanent faults. Checking For Permanent Faults
- Then continue with step 32







32. Checking the TCM

NOTE: The TCM can malfunction if there has been a short-circuit to supply voltage in the solenoid STH circuit

- Check the TCM as follows:
- Preparation:
Ignition OFF.
Reconnect connectors, reinstall components etc.
Ignition ON.
Select scrolling values.
Read off current in solenoid circuit.
Depress accelerator pedal (AP) slowly.
- The current should decrease as the accelerator pedal is depressed.
- If reading is OK:
Proceed to step 33
- If reading is incorrect:
Proceed to step 34
33. Fault-tracing information
- TCM is OK.
- Fault corrected






34. Replacing component
- Preparation:
Ignition OFF
- Try a new TCM refer to replacement. Service and Repair

NOTE:
- It is important that the solenoid STH circuit is not short-circuited to battery voltage.
A short-circuit can damage the new transmission control module (TCM).

- Then continue with step 35





35. Verification

NOTE: After repairs have been completed they must be verified as follows to ensure that the fault has been eliminated:

- Preparation:
Ignition OFF.
Reconnect connectors, reinstall components etc.
Ignition ON.
Select scrolling values.
Read off current in solenoid circuit.
Depress accelerator pedal slowly.
- The current should decrease as the accelerator pedal is depressed.
- If reading is OK:
Fault corrected
- If reading is incorrect:
Proceed to step 36
36. Fault-tracing information
- The verification result shows that the fault persists.
- Do you want to exit fault-tracing?
- Yes:
Fault not corrected
- No:
Proceed to step 1





37. Intermittent fault
- Preparation:
Ignition OFF
- Check transmission and TCM connectors for:
Loose connections according to step 5 of checking for intermittent faults. Checking For Intermittent Faults
Contact resistance and oxidation according to step 3 of checking for intermittent faults. Checking For Intermittent Faults
- Check cable between solenoid STH and transmission control module (TCM) #A22 and #A23 for
An intermittent open-circuit according to step 2 of checking for intermittent faults. Checking For Intermittent Faults
An intermittent short-circuit to ground according to step 3 of checking for intermittent faults. Checking For Intermittent Faults
- Check cable between ground terminal 31/32 and transmission control module (TCM) #A29 for an intermittent open-circuit according to step 2 of checking for intermittent faults. Checking For Intermittent Faults
- Check ground terminal 31/32 for contact resistance and oxidation according to step () of checking for intermittent faults. Checking For Intermittent Faults
- Then continue with step 38
38. Fault-tracing information
- For intermittent faults fault-tracing is not followed by a verification because the fault is not present at this moment.
- Do you want to repeat fault-tracing?
- Yes:
Proceed to step 1
- No: Operation done