DTC 14

DTC 14: Stoplight Switch System








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. Measure the signal voltage at stoplight switch connector C-03 by backprobing.

1. Do not disconnect stoplight switch connector C-03.
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 stoplight switch connector C-03 terminal 3 and ground by backprobing.
- The voltage should measure battery positive voltage. (When brake pedal is depressed).
- The voltage should measure 0 V. (When brake pedal is not depressed).
4. Turn the auto-cruise control MAIN switch to the OFF position and the ignition switch to the LOCK (OFF) position.

Q:.Are all of the measured voltages satisfied?

YES: Goto Step 3.
NO: Go to Step 2.




STEP 2. Check stoplight switch connector C-03 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 13.
NO: Repair or replace the faulty connector. (Refer to Harness Connector Inspection). Go to Step 17.










STEP 3. Measure the signal voltage at stoplight switch connector C-03 by backprobing.

1. Do not disconnect stoplight switch connector C-03.
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 stoplight switch connector C03 terminal 4 and ground by backprobing.
- The voltage should measure battery positive voltage. (When brake pedal is depressed).
- The voltage should measure 0 V. (When brake pedal is not depressed).
4. Turn the auto-cruise control MAIN switch to the OFF position and the ignition switch to the LOCK (OFF) position.

Q: Are all of the measured voltages satisfied?

YES: Go to Step 6.
NO: Go to Step 4.




STEP 4. Check stoplight switch connector C-03 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 5.
NO: Repair or replace the faulty connector. (Refer to Harness Connector Inspection). Go to Step 17.










STEP 5. Check the stoplight switch.

1. Disconnect stoplight switch connector C-03.
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 stoplight switch in good condition?

YES: It can be assumed that this malfunction is intermittent. (Refer to How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction). Go to Step 17.
NO: Replace the stoplight switch. (Refer to Brake Pedal). Go to Step 17.







STEP 6. Measure the signal voltage at auto-cruise control vacuum pump connector A-O1 by backprobing.

1. Do not disconnect auto-cruise control vacuum pump connector A-01.
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.
- The voltage should measure battery positive voltage. (When brake pedal is depressed).
- The voltage should measure 0 V. (When brake pedal is not depressed).
4. Turn the auto-cruise control MAIN switch to the OFF position and the ignition switch to the LOCK (OFF) position.

Q: Are all of the measured voltages satisfied?

YES: Go to Step 9.
NO: Go to Step 7.







STEP 7. Check auto-cruise control vacuum pump connector A-01 and intermediate connector C-05 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Are the connectors and terminals in good condition?

YES: Go to Step 8.
NO: Repair or replace the faulty connector. (Refer to Harness Connector Inspection ). Go to Step 17.







STEP 8. Check the harness wire between stoplight switch connector C-03 terminal 4 and auto-cruise control vacuum pump connector A-01 terminal 1 for damage.

Q: Is the harness wire in good condition?

YES: It can be assumed that this malfunction is intermittent. (Refer to How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction). Go to Step 17.
NO: Repair the damaged harness wire Go to Step 17.







STEP 9. Measure the signal voltage at auto-cruise control- ECU connector C-21 by backprobing.

1. Do not disconnect auto-cruise control-ECU connector C-21.
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 auto-cruise control-ECU connector C-21 terminal 7 and ground by backprobing.
- The voltage should measure greater than 10 V. (When canceling constant speed driving with the auto-cruise control CANCEL switch).
4. Measure the voltage between auto-cruise control-ECU connector C-21 terminal 8 and ground by backprobing.
- The voltage should measure greater than 10 V. (When decelerating with the auto-cruise control SET switch while driving at constant speed).
5. Measure the voltage between auto-cruise control-ECU connector C-21 terminal 16 and ground by backprobing.
- The voltage should measure battery positive voltage. (When the motor is stopped during a constant road speed).
6. Turn the auto-cruise control MAIN switch to the OFF position and the ignition switch to the LOCK (OFF) position.

Q: Are all of the measured voltages satisfied?

YES: Check that DTC 14 is not set. If DTC 14 is not set, It can be assumed that this malfunction is intermittent. (Refer to How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction). If DTC 14 is set, replace the auto-cruise control-ECU, and then go to Step 17.
NO: Go to Step 10.










STEP 10. Check auto-cruise control vacuum pump connector A-01, auto-cruise control-ECU connector C-21 and intermediate connector C-212 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Are the connectors and terminals in good condition?

YES: Go to Step 11.
NO: Repair or replace the faulty connector. (Refer to Harness Connector Inspection). Go to Step 17.







STEP 11. Check the auto-cruise control vacuum pump.

1. Disconnect the vacuum hose from the auto-cruise control vacuum pump and connect a vacuum gauge to the vacuum pump.
2. Disconnect auto-cruise control vacuum pump connector A-01.
3. Check the auto-cruise control vacuum pump and valves according to the following procedure:
- Connect the positive battery terminal to auto-cruise control vacuum pump connector A-01 terminal 1, and the negative battery terminal to terminals 2, 3 and 4. The vacuum gauge should read greater than 27 kPa (8.0 in.Hg).
- The vacuum should be maintained when terminal 4 is disconnected from the negative battery terminal while terminals 1, 2 and 3 remain connected. 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. 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.
4. Connect the auto-cruise control vacuum pump connector A-01.

Q: Are all of the above values satisfied?

YES: Go to Step 12.
NO: Replace the auto-cruise vacuum pump. Go to Step 17.







STEP 12. Check the harness wire between auto-cruise control vacuum pump connector A-O1 terminals 2, 3, 4 and auto-cruise control-ECU connector C-21 terminals 7, 8,16 for damage.

Q: Is the harness wire in good condition?

YES: Check that DTC 14 is not set. If DTC 14 is not set, It can be assumed that this malfunction is intermittent. (Refer to How to Use Troubleshooting/Inspection Service Points - How to Cope with intermittent Malfunction). If DTC 14 is set, replace the auto-cruise control-ECU, and then go to Step 17.
NO: Repair the damaged harness wire. Go to Step 17.







STEP 13. Measure the signal voltage at auto-cruise control-ECU connector C-21 by backprobing.

1. Do not disconnect auto-cruise control-ECU connector C-21.
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 auto-cruise control-ECU connector C-21 terminal 5 and ground by backprobing.
- The voltage should measure battery positive voltage. (When brake pedal is depressed).
- The voltage should measure 0 V. (When brake pedal is not depressed).
4. Turn the auto-cruise control MAIN switch to the OFF position and the ignition switch to the LOCK (OFF) position.

Q: Are all of the measured voltages satisfied?

YES: Go to Step 14.
NO: Go to Step 16.







STEP 14. Check stoplight switch connector C-03 and intermediate connector C-209 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Are the connectors and terminals in good condition?

YES: Go to Step 15.
NO: Repair or replace the faulty connector. (Refer to Harness Connector Inspection). Go to Step 17.







STEP 15. Check the harness wire between stoplight switch connector C-03 terminal 3 and auto-cruise control-ECU connector C-21 terminal 5 for damage.

Q: Are the harness wire in good condition?

YES: It can be assumed that this malfunction is intermittent. (Refer to How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction). Go to Step 17.
NO: Repair the damaged harness wire. Go to Step 17.




STEP 16. Check auto-cruise control-ECU connector C-21 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Are the connector and terminals in good condition?

YES: Check that DTC 14 is not set. If DTC 14 is not set, It can be assumed that this malfunction is intermittent. (Refer to How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction). If DTC 14 is set, replace the auto-cruise control-ECU, and then go to Step 17.
NO: Repair or replace the faulty connector. (Refer to Harness Connector Inspection). Go to Step 17.

STEP 17. Check the diagnostic trouble codes.

Q: Is DTC 14 set?

YES: Go to Step 1.
NO: This procedure is complete.