DTC 22

DTC 22: Stoplight Switch System

CIRCUIT OPERATION

- Battery positive voltage is supplied to the stoplight switch (terminal 2 and 3).
- When the brake pedal is depressed, battery positive voltage is applied to the ECM [M/T] or PCM [A/T] (terminal 9 and 33).

DTC SET CONDITIONS

Check Condition

- The "CRUISE" indicator light illuminates.
Judgement Criteria

- Short in stop light switch circuit.
- Open circuit in the brake switch circuit (between ECM [M/T] or PCM [A/T] terminal 33 and ground).

TROUBLESHOOTING HINTS (THE MOST LIKELY CAUSES FOR THIS CASE:)

- Malfunction of the stoplight switch.
- Damaged harness or connector.
- Malfunction of the ECM [M/T] or PCM [A/T].

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

STEP 1. Using scan tool MB991958, check data list item 74: Brake light switch.

(1)
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.

Connect scan tool MB991958 to the data link connector. (Refer to Reading and Clearing Diagnostic Trouble Codes).
(2)Turn the ignition switch to the "ON" position.
(3)Set scan tool MB991958 to data reading mode for auto-cruise control system. (Refer to Scan Tool Testing and Procedures).

- Item 74, Brake light switch.
- When the brake pedal is depressed, the display on scan tool MB991958 should be "ON".
- When the brake pedal is released, 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 14.

NO Go to Step 2.

STEP 2. Check the stoplight operation.

(1)Check the stoplight operation.

- When the brake pedal is depressed, the stoplight will illuminate.
- When the brake pedal is released, the stoplight does not illuminate.

Q. Does the stoplight illuminate when the brake pedal is depressed and go out when the brake pedal is released?

YES Go to Step 3.
NO Go to Step 6.
STEP 3. Measure the terminal voltage at ECM [M/T] or PCM [A/T] connector B-18.

(1)Disconnect all the connectors from the ECM [M/T] or PCM [A/T].

(2)Connect special tool MB991923 between the ECM [M/T] or PCM [A/T] and the body-side harness connector.
(3)Turn the ignition switch to the "ON" position.

(4)Measure the terminal voltage between special tool 18-pin connector terminal 9 (ECM [M/T] or PCM [A/T] connector B-18 terminal 9) and ground.

- When the brake pedal is depressed, the voltage should measure battery positive voltage (approximately 12 volts).
- When the brake pedal is released, the voltage should measure 1 volt or less.
(5)Turn the ignition switch to the "LOCK" (OFF) position.
(6)Disconnect special tool MB991923 between the ECM [M/T] or PCM [A/T] and the body-side harness connector.
(7)Reconnect all the connectors to the ECM [M/T] or PCM [A/T].

Q. Is the measured voltage battery positive voltage (approximately 12 volts) when the brake pedal is depressed and 1 volt or less when the brake pedal is released?

YES Go to Step 13.

NO Go to Step 4.

STEP 4. Check ECM [M/T] or PCM [A/T] connector B-18 and joint connector (1) C-28 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 5.

NO Repair or replace the damaged components. Harness Connector Inspection). Then go to Step 22.

STEP 5. Check the harness wire between ECM [M/T] or PCM [A/T] connector B-18 terminal 9 and joint connector (1) C-28 terminal 14 for damage.

Q. Is the harness wire in good condition?

YES Go to Step 13.

NO Repair the damaged harness wire. Then go to Step 22.

STEP 6. Measure the power supply voltage at stoplight switch connector C-103 by backprobing.

(1)Disconnect stoplight switch connector C-103.

(2)Measure the power supply voltage between stoplight switch connector C-103 terminal 2 and ground.
(3)Reconnect stoplight switch connector C-103.

Q. Is the measured voltage battery positive voltage (approximately 12 volts)?

YES Go to Step 10.

NO Go to Step 7.

STEP 7. Check stoplight switch connector C-103 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 8.

NO Repair or replace the damaged components. Harness Connector Inspection). Then go to Step 22.

STEP 8. Check the harness wire between stoplight switch connector C-103 terminal 2 and fuse number 11 at the relay box at engine compartment for damage.

Q. Is the harness wire in good condition?

YES Go to Step 9.

NO Repair the damaged harness wire. Then go to Step 22.

STEP 9. Check the fuse number 11 at the relay box at engine compartment.

Q. Is the fuse in good condition?

YES Go to Step 10.

NO Check the stoplight system harness and replace the fuse. Then go to Step 22.

STEP 10. Check the stoplight switch.

(1)Remove the stoplight switch. Service and Repair).

(2)Connect an ohmmeter to the stoplight switch between terminals 1 and 2.
(3)Check for continuity between the terminals when the plunger of the stoplight switch is pushed in and when it is released.
(4)The stoplight switch is operating properly if the circuit is open between terminals 1 and 2 when the plunger is pushed in to a depth of within 4.0 mm (0.16 inch) from the outer case edge surface, and if the resistance value is less than 2 ohms between terminals 1 and 2 when it is released.

Q. Is the stoplight switch operating properly?

YES Install the stoplight switch. Service and Repair).
Then go to Step 11.

NO Replace the stoplight switch. Service and Repair).
Then go to Step 22.

STEP 11. Check stoplight switch connector C-103 and joint connector (1) C-28 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 12.

NO Repair or replace the damaged components. Harness Connector Inspection). Then go to Step 22.

STEP 12. Check the harness wire between stoplight switch connector C-103 terminal 1 and joint connector (1) C-28 terminal 12 for damage.

Q. Is the harness wire in good condition?

YES Go to Step 13.

NO Repair the damaged harness wire. Then go to Step 22.

STEP 13. Using scan tool MB991958, check data list item 74: Brake light switch.

(1)Disconnect all the connectors from the ECM [M/T] or PCM [A/T].

(2)Connect special tool MB991923 between the ECM [M/T] or PCM [A/T] and the body-side harness connector.
(3)Turn the ignition switch to the "ON" position.

(4)Measure the terminal voltage between special tool 23-pin connector (without red tape) terminal 33 (ECM [M/T] or PCM [A/T] connector B-19 terminal 33) and ground.

- When the brake pedal is depressed, the voltage should measure battery positive voltage (approximately 12 volts).
- When the brake pedal is released, the voltage should measure 1 volt or less.
(5)Turn the ignition switch to the "LOCK" (OFF) position.
(6)Disconnect special tool MB991923 between the ECM [M/T] or PCM and the body-side harness connector.
(7)Reconnect all the connectors to the ECM [M/T] or PCM.

Q. Is the measured voltage battery positive voltage (approximately 12 volts) when the brake pedal is depressed and 1 volt or less when the brake pedal is released?

YES Go to Step 20.

NO Go to Step 16.

STEP 16. Check the stoplight switch.

(1)Remove the stoplight switch. Service and Repair).

(2)Connect an ohmmeter to the stoplight switch between terminals 3 and 4.
(3)Check for continuity between the terminals when the plunger of the stoplight switch is pushed in and when it is released.
(4)The stoplight switch is operating properly if the circuit is open between terminals 3 and 4 when the plunger is released, and if resistance value is less than 2 ohms between terminals 3 and 4 when the plunger is pushed in to a depth of within 4.5 mm (0.18 inch) from the outer case edge surface.

Q. Is the stoplight switch operating properly?

YES Install the stoplight switch. Service and Repair).
Then go to Step 17.

NO Replace the stoplight switch. Service and Repair).
Then go to Step 22.

STEP 17. Check ECM [M/T] or PCM [A/T] connector B-19 and stoplight switch connector C-103 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 18.

NO Repair or replace the damaged components. Harness Connector Inspection). Then go to Step 22.

STEP 18. Check the harness wire between ECM [M/T] or PCM [A/T] connector B-19 terminal 33 and stoplight switch connector C-103 terminal 3 for damage.

Q. Is the harness wire in good condition?

YES Go to Step 19.

NO Repair the damaged harness wire. Then go to Step 22.

STEP 19. Check the harness wire between stoplight switch connector C-103 terminal 4 and ground for damage.

Q. Is the harness wire in good condition?

YES Go to Step 20.

NO Repair the damaged harness wire. Then go to Step 22.

STEP 20. Using scan tool MB991958, check data list item 89: Normally closed brake switch.

(1)
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.

Connect scan tool MB991958 to the data link connector. (Refer to Reading and Clearing Diagnostic Trouble Codes).
(2)Turn the ignition switch to the "ON" position.
(3)Set scan tool MB991958 to data reading mode for auto-cruise control system. (Refer to Scan Tool Testing and Procedures).

- Item 89, Normally closed brake switch.
- When the brake pedal is depressed, the display on scan tool MB991958 should be "ON".
- When the brake pedal is released, 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 21.

NO Replace the ECM [M/T] or PCM [A/T]. Immobilizer System). Then go to Step 22.

STEP 21. Read the diagnostic trouble codes.

Read the diagnostic trouble codes. (Refer to Reading and Clearing Diagnostic Trouble Codes).

Q. Is DTC 22 set?

YES Replace the ECM [M/T] or PCM [A/T]. Immobilizer System). Then go to Step 22.
NO It can be assumed that this malfunction is intermittent. How to Cope With Intermittent Malfunctions).
STEP 22. Read the diagnostic trouble codes.

Read the diagnostic trouble codes. (Refer to Reading and Clearing Diagnostic Trouble Codes).

Q. Is DTC 22 set?

YES Return to Step 1.
NO The procedure is complete.