Code No. P1788: A/T Control Relay System
 |
OPERATION
DIAGNOSIS CODE SET CONDITIONS
PROBABLE CAUSES
- Malfunction of A/T control relay
- Damaged harness wires and connectors
- Malfunction of the A/T-ECU
DIAGNOSIS PROCEDURE |
STEP 1. M.U.T.-III data list |
Item 8: Relay voltage (Refer to data list reference table  ). |
Q.
Is the check result normal?
|
 Intermittent malfunction (Refer to GROUP 00 -
How to Cope with Intermittent Malfunction ). |
|
 Go to Step 2. |
|
STEP 2. Check the A/T control relay |
| Refer to . |
Q.
Is the check result normal?
|
| Go to Step 3. |
|
| Replace the A/T control relay. |
|
STEP 3. Connector check: A-16X A/T control relay connector |
| Check for the contact with terminals. |
Q.
Is the check result normal?
|
| Go to Step 4. |
|
| Repair the defective connector. |
|
STEP 4. Measure the voltage at A/T control relay connector A-16X. |
| Remove the A/T control relay, and measure the voltage between terminal No.4 and earth at the relay box side. |
| OK: System voltage |
Q.
Is the check result normal?
|
| Go to Step 7. |
|
| Go to Step 5. |
|
STEP 5. Check the harness between A/T control relay connector A-16X terminal No.4 and battery. |
| Check the power supply line for short or open circuit. |
Q.
Is the check result normal?
|
| Go to Step 6. |
|
| Repair the wiring harness. |
|
STEP 6. M.U.T.-III data list |
| Item 8: Relay voltage (Refer to data list reference table ). |
Q.
Is the check result normal?
|
| The trouble can be an intermittent malfunction (Refer to GROUP 00 -
How to Cope with Intermittent Malfunction ). |
|
| Replace the A/T-ECU. |
|
STEP 7. Measure the voltage at the A/T control relay connector A-16X. |
| (1)Turn the ignition switch to the ON position. |
| (2)Disconnect the A/T control relay, and measure the voltage between terminal No.2 and earth at the relay box side. OK: System voltage |
Q.
Is the check result normal?
|
| Go to Step 10. |
|
| Go to Step 8. |
|
STEP 8. Connectors check: C-128 intermediate connector, C-317 ETACS-ECU connector |
| Check for the contact with terminals. |
Q.
Is the check result normal?
|
| Go to Step 9. |
|
| Repair the defective connector. |
|
STEP 9. Check the wiring harness between A/T control relay connector A-16X terminal No.2 and ETACS-ECU connector C-317 terminal No.5. |
| Check the power supply line for short or open circuit. |
Q.
Is the check result normal?
|
| Go to Step 6. |
|
| Repair the wiring harness. |
|
STEP 10. Measure the voltage at A/T-ECU connector C-34. |
| (1)Install the A/T control relay. |
| (2)Turn the ignition switch to the ON position. |
| (3)Measure the voltage between A/T-ECU connector C-34 terminal No.43, No.49 and earth. OK: System voltage |
Q.
Is the check result normal?
|
| Go to Step 13. |
|
| Go to Step 11. |
|
STEP 11. Connector check: C-34 A/T-ECU connector |
| Check for the contact with terminals. |
Q.
Is the check result normal?
|
| Go to Step 12. |
|
| Repair the defective connector. |
|
STEP 12. Check the harness between A/T control relay connector A-16X terminal No.3 and A/T-ECU connector C-34 terminal No.43, 49. |
| Check the power supply line for short or open circuit. |
Q.
Is the check result normal?
|
| Go to Step 6. |
|
| Repair the wiring harness. |
|
STEP 13. Connector check: C-34 A/T-ECU connector |
| Check for the contact with terminals. |
Q.
Is the check result normal?
|
| Go to Step 14. |
|
| Repair the defective connector. |
|
STEP 14. Check the harness between A/T control relay connector A-16X terminal No.1 and A/T-ECU connector C-34 terminal No.44. |
| Check the output line for short or open circuit. |
Q.
Is the check result normal?
|
| Go to Step 6. |
|
| Repair the wiring harness. |
|