DTC 15

DTC 15: Auto-cruise Control Switch System

Auto Cruise Control Switch System Circuit:

CIRCUIT OPERATION
This circuit judges the signals of each switch (SET, RESUME, CANCEL and MAIN) of the auto-cruise control switch. The auto-cruise control-ECU detects the state of the auto-cruise control switch by sensing the voltages shown below.
- When all switches are OFF, the ECU detects 3.5 - 5.0 volts.
- When the SET switch is ON, the ECU detects 0.4 - 2.3 volts.
- When the RESUME switch is ON, the ECU detects 2.3 - 3.5 volts.
- When the CANCEL switch is ON, the ECU detects 0.4 volts or less.
- When the MAIN switch is ON, the ECU detects 7.0 volts.

DTC SET CONDITIONS
This code is set when the auto-cruise control RESUME switch, SET switch or CANCEL switch stays ON.

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

DIAGNOSIS

Required Special Tool:
- MB991223: Harness Set




STEP 1. Measure the 12-Volt supply circuit voltage at auto- cruise control switch connector C-207.
1. Disconnect auto-cruise control switch connector C-207.
2. Turn the ignition switch to the ON position.
3. Measure the voltage between auto-cruise control switch connector C-207 terminal and ground.
- The voltage should measure battery positive voltage.
4. Turn the ignition switch to the LOCK (OFF) position, connect auto-cruise control switch connector C-64.

Q: Is the measured voltage battery positive voltage?

YES: Go to Step 5.
NO: Go to Step 2.




STEP 2. Check auto-cruise control switch connector C-207 and clock spring connectors C-205 and C-214 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 3.
NO: Repair or replace the faulty connector. (Refer to Harness Connector Inspection). Go to Step 10

STEP 3. Check the clock spring.
Refer to Air Bag Modules and Clock Spring.

Q: Is the clock spring in good condition?

YES: Go to Step 4.
NO: Replace the clock spring. (Refer to Air Bag Modules and Clock Spring). Go to Step 10.




STEP 4. Check the harness wire between junction block fuse number 21 and auto-cruise control switch connector C-207 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 10.
NO: Repair the damaged harness wire. Go to Step 10.







STEP 5. 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.
3. Measure the voltage between auto-cruise control-ECU connector C-21 terminal 12 and ground by backprobing.
- The voltage should measure 6.8 and 7.2 volts. (The MAIN switch is at the ON position.)
4. Measure the voltage between auto-cruise control-ECU connector C-21 terminal 9 and ground by backprobing, when the MAIN switch is at the ON position.
- The voltage should measure 0 volt. (SET, RESUME and CANCEL switches are at the OFF position.)
- The voltage should measure between 0.4 and 2.3 volts. (SET switch is at the ON position.)
- The voltage should measure between 2.3 and 3.5 volts. (RESUME switch is at the ON position.)
- The voltage should measure between 1 volt or less. (CANCEL switch is at the ON position.)
5. Turn the ignition switch to the LOCK (OFF) position.

Q: Are all of the measured voltages satisfied?

YES: Check that DTC is is not set. If DTC 15 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 15 is set, replace the auto-cruise control-ECU, and then go to Step 10
NO: Go to Step 6.







STEP 6. Check auto-cruise control-ECU connector C-21, auto-cruise control switch connector C-207 and clock spring connectors C-205 and C-214 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 7.
NO: Repair or replace the faulty connector. (Refer to Harness Connector Inspection). Go to Step 10




STEP 7. Check the auto-cruise control switch.

1. Remove the auto-cruise control switch.
2. Measure the resistance between the terminals when each of the SET, RESUME, CANCEL and MAIN switch is pressed.




Q: Does the measured values meet the table above?

YES: Go to Step 8.
NO: Replace the auto-cruise control switch. Go to Step 10.

STEP 8. Check the clock spring.
Refer to Air Bag Modules and Clock Spring.

Q: Is the clock spring in good condition?

YES: Go to Step 9.
NO: Replace the clock spring. (Refer to Air Bag Modules and Clockspring). Go to Step 10.







STEP 9. Check the harness wire between auto-cruise control-ECU connector C-21 terminals 9,12 and auto-cruise control switch connector C-207 terminals 2, 3 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 Trouble shooting/Inspection Service Points - How to Cope with Intermittent Malfunction). Go to Step 10.
NO: Repair the damaged harness wire. Go to Step 10.

STEP 10. Check the diagnostic trouble codes.

Q: Is DTC 15 set?
YES: Go to Step 1.
NO: This procedure is complete.