DTC 15

DTC15 : Auto-cruise Control Switch System

Auto-cruise Control Switch System Circuit (Part 1):

Auto-cruise Control Switch System Circuit (Part 2):

CIRCUIT OPERATION
This circuit judges the signals of each switch ("COAST/SET", "ACC/RES" and "CANCEL") of the auto-cruise control switch. The PCM detects the state of the auto-cruise control switch by sensing the voltages shown below.

- When all switches are OFF: 4.7 - 5.0 volts
- When the "CRUISE" (MAIN) switch is "ON": 0 - 0.3 volt
- When the "COAST/SET" switch is ON: 2.0 - 2.8 volts
- When the "ACC/RES" switch is ON: 3.3 - 4.1 volts
- When the "CANCEL" switch is ON: 0.8 - 1.5 volts

DTC SET CONDITIONS

Check Condition

- The "CRUISE" indicator light illuminates.

Judgement Criteria
- If the auto-cruise control switch is operated, this DTC will be set when the PCM terminal voltage is different from the standard value.

TROUBLESHOOTING HINTS (THE MOST LIKELY CAUSES FOR THIS CASE:)
- Malfunction of the auto-cruise control switch.
- Malfunction of the clock spring.
- Damaged harness or connector.
- Malfunction of the PCM.

DIAGNOSIS

Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A

- MB991223: Harness Set
- MB991923: Power Plant ECU Check Harness
- MB992006: Extra Fine Probe

STEP 1. Using scan tool MB991958, check data list item 86: Main Switch, list item 92: Set Switch, item 91: Resume Switch and list item 75: Cancel Switch.

CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.

1. Connect scan tool MB991958 to the data link connector. How to Connect the Scan Tool (M.U.T. -III)
2. Turn the ignition switch to the "ON" position.
3. Set scan tool MB991958 to data reading mode for auto-cruise control system. Reading Diagnostic Trouble Codes
- Item 86: Main Switch.
- When "CRUISE" (MAIN) switch is at the "ON" position, the display on scan tool MB991958 should be "ON".
- When ""CRUISE" (MAIN) switch is at the "OFF" position, the display on scan tool MB991958 should be "OFF".

- Item 92: Set Switch.
- When "COAST/SET" switch is at the "ON" position, the display on scan tool MB991958 should be "ON".
- When "COAST/SET" switch is at the "OFF" position, the display on scan tool MB991958 should be "OFF".

- Item 91: Resume Switch.
- When "ACC/RES" switch is at the "ON" position, the display on scan tool MB991958 should be "ON".
- When "ACC/RES" switch is at the "OFF" position, the display on scan tool MB991958 should be "OFF".

- Item 75: Cancel Switch.
- When "CANCEL" switch is at the "ON" position, the display on scan tool MB991958 should be "ON".
- When "CANCEL" switch is at the "OFF" position, the display on scan tool MB991958 should be "OFF".

4. Turn the ignition switch to the "LOCK" (OFF) position.
5. Disconnect scan tool MB991958.

Q: Is the switch operating properly?

YES : Go to Step 17.

NO : Go to Step 2.

STEP 2. Measure the power supply voltage at auto-cruise control switch connector C-302 by backprobing.

1. Remove the air bag module (driver's side).

2. Connect the negative (-) battery cable.
3. Do not disconnect auto-cruise control switch connector C-302.
4. Turn the ignition switch to the "ON" position.
5. The "CRUISE" (MAIN) switch to the "OFF" position.

6. Measure the power supply voltage between auto-cruise control switch connector C-302 terminal 2 and ground by backprobing.
7. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the measured voltage between 4.7 and 5.0 volts?

YES : Go to Step 9.

NO : Go to Step 3.

STEP 3. Measure the power supply voltage at PCM connector B-19.

1. Disconnect all the connectors from the PCM.

2. Connect special tool MB991923 between the PCM and the body-side harness connector.
3. Turn the ignition switch to the "ON" position.
4. The "CRUISE" (MAIN) switch to the "OFF" position.

5. Measure the power supply voltage between special tool 18-pin connector terminal 12 (PCM connector B-19 terminal 12) and ground.
6. Turn the ignition switch to the "LOCK" (OFF) position.
7. Disconnect special tool MB991923 between the PCM and the body-side harness connector.
8. Reconnect all the connectors to the PCM.

Q: Is the measured voltage between 4.7 and 5.0 volts?

YES : Go to Step 6.

NO : Go to Step 4.

STEP 4. Check PCM connector B-19 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. Install the air bag module (driver's side). Then go to Step 18.

STEP 5. Check the harness for short circuit to ground between the PCM connector B-19 terminal 12 and the auto-cruise control switch connector C-302 terminal 2.

1. Disconnect PCM connector B-19 and measure at the harness connector side.
2. Turn the ignition switch to the "LOCK" (OFF) position.

3. Measure the continuity between PCM connector B-19 terminal 12 and ground.
4. Reconnect PCM connector B-19.

Q: Is the measured continuity open circuit?

YES : Install the air bag module (driver's side). Then go to Step 17.

NO : Go to Step 6.

STEP 6. Check intermediate connector C-29, auto-cruise control switch connector C-302 and clock spring connectors C-303 and C-306 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. Install the air bag module (driver's side). Then go to Step 18.

STEP 7. Check the harness wire between PCM connector B-19 terminal 12 and auto-cruise control switch connector C-302 terminal 2 for damage.

Q: Are the harness wires in good condition?

YES : Go to Step 8.

NO : Repair the damaged harness wire and install the air bag module (driver's side). Then go to Step 18.

STEP 8. Check the clock spring.

Refer to Air Bag Modules and Clock Spring.

Q: Is the clock spring in good condition?

YES : It can be assumed that this malfunction is intermittent. Install the air bag module (driver's side). Then go to Step 18.

NO : Replace the clock spring and install the air bag module (driver's side). Then go to Step 18.

STEP 9. Measure the ground voltage at auto-cruise control switch connector C-302 by backprobing.

1. Do not disconnect auto-cruise control switch connector C-302.
2. Turn the ignition switch to the "ON" position.
3. Turn the "CRUISE" (MAIN) switch to the "ON" position.

4. Measure the ground voltage between auto-cruise control switch connector C-302 terminal 3 and ground by backprobing.
5. Turn the "CRUISE" (MAIN) switch to the "OFF" position.
6. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the measured voltage 0.5 volt or less?

YES : Go to Step 15.

NO : Go to Step 10.

STEP 10. Measure the ground voltage at PCM connector B-20.

1. Disconnect all the connectors from the PCM.

2. Connect special tool MB991923 between the PCM and the body-side harness connector.
3. Turn the ignition switch to the "ON" position.
4. Turn the "CRUISE" (MAIN) switch to the "ON" position.

5. Measure the ground voltage between special tool 23-pin connector (without red tape) terminal 28 (PCM connector B-20 terminal 28) and ground.
6. Turn the "CRUISE" (MAIN) switch to the "OFF" position.
7. Turn the ignition switch to the "LOCK" (OFF) position.
8. Disconnect special tool MB991923 between the PCM and the body-side harness connector.
9. Reconnect all the connectors to the PCM.

Q: Is the measured voltage 0.5 volt or less?

YES : Go to Step 12.

NO : Go to Step 11.

STEP 11. Check PCM connector B-20 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Are the connector and terminals in good condition?

YES : Install the air bag module (driver's side). Then go to Step 17.

NO : Repair or replace the faulty connector. Install the air bag module (driver's side). Then go to Step 18.

STEP 12. Check PCM connector B-20, intermediate connector C-29, auto-cruise control switch connector C-302 and clock spring connectors C-303 and C-306 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 13.

NO : Repair or replace the faulty connector. Install the air bag module (driver's side). Then go to Step 18.

STEP 13. Check the harness wire between PCM connector B-20 terminal 28 and auto-cruise control switch connector C-302 terminal 3 for damage.

Q: Are the harness wires in good condition?

YES : Go to Step 14.

NO : Repair the damaged harness wire and install the air bag module (driver's side). Then go to Step 18.

STEP 14. Check the clock spring.

Refer to Air Bag Modules and Clock Spring.

Q: Is the clock spring in good condition?

YES : It can be assumed that this malfunction is intermittent. Then go to Step 18.

NO : Replace the clock spring and install the air bag module (driver's side). Then go to Step 18.

STEP 15. Check auto-cruise control switch connector C-302 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 16.

NO : Repair or replace the faulty connector. Install the air bag module (driver's side). Then go to Step 18.

STEP 16. Check the auto-cruise control switch.

1. Remove auto-cruise control switch.
2. Measure the resistance between terminal 2 and terminal 3 when each of the "CRUISE" (MAIN), "COAST/SET", "ACC/RES" and "CANCEL" switch is pressed.

Q: Is the resistance within specifications?

YES : Install the air bag module (driver's side). Then go to Step 17.

NO : Replace the auto-cruise control switch.. Install the air bag module (driver's side). Then go to Step 18.

STEP 17. Using scan tool MB991958, read the diagnostic trouble code.