DTC 14

Auto-cruise Vacuum Pump Power Supply:

Connectors:

CIRCUIT OPERATION
This circuit supplies the power to the vacuum pump. The battery positive voltage is supplied to the auto-cruise control vacuum pump by turning on the transistor at terminal number 16 of the auto-cruise control-ECU. The conditions for turning on the transistor at terminal number 16 of the auto-cruise control-ECU are as follows.
- Ignition switch "ON"
- Auto-cruise control main switch "ON"
- Stoplight switch ON

DTC SET CONDITIONS
None of the drive signals from release valve, control valve and motor of the auto-cruise vacuum pump are input to the auto-cruise control-ECU.

TROUBLESHOOTING HINTS
The most likely causes for this code to be set are:
- Malfunction of the stoplight switch
- Malfunction of the auto-cruise vacuum pump
- Damaged harness or connector.
- Malfunction of the auto-cruise control-ECU

DIAGNOSIS

Required Special Tool:
- MB991223: Harness Set

STEP 1. Check the output circuit voltage at stoplight switch connector C-102 by backprobing.
1. Do not disconnect stoplight switch connector C-102.
2. Turn the ignition switch to the "ON" position.




3. Measure the voltage between terminal 3 and ground by backprobing.
4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the voltage approximately battery positive voltage?

YES: Go to Step 3.

NO: Go to Step 2.




STEP 2. Check stoplight switch connector C-102.

Q: Is the connector damaged?

YES: Repair or replace connector. Refer to Harness Connector Inspection. Then check that diagnostic trouble code 14 is not output.

NO: Go to Step 13.

STEP 3. Check the output circuit voltage at stoplight switch connector C-102 by backprobing.
1. Do not disconnect stoplight switch connector C-102.
2. Turn the ignition switch to the "ON" position and the auto- cruise control main switch to the "ON" position.




3. Measure the voltage between terminal 4 and ground by backprobing.
4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the voltage approximately battery positive voltage?

YES: Go to Step 6.

NO: Go to Step 4.




STEP 4. Check stoplight switch connector C-102.

Q: Is the connector damaged?

YES: Repair or replace connector. Refer to Harness Connector Inspection. Then check that diagnostic trouble code 14 is not output.

NO: Go to Step 5.







STEP 5. Check the stoplight switch.
1. Disconnect stoplight switch connector C-102.
2. Connect an ohmmeter to the stoplight switch between terminals 3 and 4, and check whether there is continuity when the plunger of the stoplight switch is pushed in and an open circuit when it is released.
3. The stoplight switch is in good condition if the circuit is open when the plunger is pushed in to a depth of within 4 mm (0.2 inch) from the outer case edge surface, and if there is continuity when it is released.

Q: Is the circuit is open?

YES: Replace the stoplight switch. Refer to Brake Pedal. Then check that a diagnostic trouble code 14 is not output.

NO: Check that diagnostic trouble code 14 is not output. If diagnostic trouble code 14 is output, replace the auto-cruise control-ECU. Then check that diagnostic trouble code 14 is not output.

STEP 6. Check the output circuit voltage at auto-cruise control vacuum pump connector A-26 by backprobing.
1. Do not disconnect auto-cruise control vacuum pump connector A-26.
2. Turn the ignition switch to the "ON" position and the auto-cruise control main switch to the "ON" position.




3. Measure the voltage between terminal 1 and ground by backprobing.
4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the voltage approximately battery positive voltage?

YES: Go to Step 8.

NO: Go to Step 7.










STEP 7. Check auto-cruise control vacuum pump connector A-26 and intermediate connector C-102, C-111.

Q: Is any connector damaged?

YES: Repair or replace connector. Refer to Harness Connector Inspection. Then check that diagnostic trouble code 14 is not output.

NO: Check the harness wire between stoplight switch connector C-102 and auto-cruise control vacuum pump connector A-26 for open circuit or damage. Then repair if necessary. Then check that diagnostic trouble code 14 is not output.

STEP 8. Check the output circuit voltage at auto-cruise control-ECU connector C-107 by backprobing.
1. Do not disconnect auto-cruise control-ECU connector C-107.
2. Turn the ignition switch to the "ON" position and the auto-cruise control main switch to the "ON" position.




3. Measure the voltage between terminal 7 and ground by backprobing.
- Voltage should be battery positive voltage. [When decelerating with the "SET" switch while driving at constant speed (Release valve open).]

4. Measure the voltage between terminal 8 and ground by backprobing.
- Voltage should be battery positive voltage. [When decelerating with the "SET" switch while driving at constant speed. (Control valve open).]

5. Measure the voltage between terminal 16 and ground by backprobing.
- Voltage should be battery positive voltage. (When the motor is stopped during a constant road speed.)

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

Q: Are all of the above values satisfied?

YES: Check that diagnostic trouble code 14 is not output. If diagnostic trouble code 14 is output, replace the auto-cruise control-ECU. Then check that diagnostic trouble code 14 is not.

NO: Go to Step 9.







STEP 9. Check auto-cruise control-ECU connector C-107 and intermediate connector C-107, C-111.

Q: Is the connector damaged?

YES: Repair or replace connector.
Refer to Harness Connector Inspection.
Then check that diagnostic trouble code 14 is not output.

NO: Go to Step 10.




STEP 10. Check auto-cruise control vacuum pump connector A-26.

Q: Is the connector damaged?

YES: Repair or replace connector. Refer to Harness Connector Inspection. Then check that diagnostic trouble code 14 is not output.

NO: Go to Step 11.

STEP 11. Check the auto-cruise vacuum pump.
1. Disconnect the vacuum hose from the auto-cruise vacuum pump and connect a vacuum gauge to the vacuum pump.
2. Disconnect the vacuum pump connector.




3. Check the auto-cruise vacuum pump and valves according to the following procedure:
- Connect the positive battery terminal to auto-cruise vacuum pump connector terminal 1, and the negative battery terminal to terminals 2, 3, and 4. The vacuum gauge should read 27 kPa (8.0 in Hg) or more.
- The vacuum should be maintained when terminal 4 is disconnected from the negative battery terminal while terminals 1, 2, and 3 remain connected. Then the vacuum gauge should read 0 kPa (0 in Hg) when terminal 2 is disconnected from the negative battery terminal while terminals 1, and 3 remain connected.
- The vacuum should be maintained when terminal 4 is disconnected from the negative battery terminal while terminals 1, 2, and 3 remain connected. Then the vacuum gauge should read 0 kPa (0 in Hg) when terminal 3 is disconnected from the negative battery terminal while terminals 1, and 2 remain connected.

Q: Are all of the above values satisfied?

YES: Go to Step 12.

NO: Replace the auto-cruise vacuum pump. Then check that diagnostic trouble code 14 is not output.







STEP 12. Check the harness wire between auto-cruise control vacuum pump connector A-26 terminal 2, 3, 4 and auto-cruise control-ECU connector C-107 terminal 7, 8, 16.

Q: Is any harness wire between auto-cruise control vacuum pump connector A-26 and auto-cruise control-ECU connector C-107 damaged?

YES: Repair harness wire and then check that diagnostic trouble code 14 is not output.

NO: Check that diagnostic trouble code 14 is not output. If diagnostic trouble code 14 is output, replace the auto-cruise control-ECU. Then check that diagnostic trouble code 14 is not output.

STEP 13. Check the output circuit voltage at auto-cruise control-ECU connector C-107 by backprobing.
1. Do not disconnect auto-cruise control-ECU connector C-107.
2. Turn the ignition switch to the "ON" position and the auto-cruise control main switch to the "ON" position.




3. Measure the voltage between terminal 5 and ground by backprobing.
4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the voltage approximately battery positive voltage?

YES: Go to Step 14.

NO: Go to Step 15.




STEP 14. Check intermediate connector C-108.

Q: Is any connector damaged?

YES: Repair or replace connector Refer to Harness Connector Inspection. Then check that diagnostic trouble code 14 is not output.

NO: Check the harness wire between auto-cruise control-ECU connector C-107 and stoplight switch connector C-102 for open circuit or damage. Then repair if necessary. Then check that diagnostic trouble code 14 is not output.




STEP 15. Check auto-cruise control-ECU connector C-107.

Q: Is the connector damaged?

YES: Repair or replace connector. Refer to Harness Connector Inspection. Then check that diagnostic trouble code 14 is not output.

NO: Check that diagnostic trouble code 14 is not output. If diagnostic trouble code 14 is output, replace the auto-cruise control-ECU. Then check that diagnostic trouble code 14 is not output.