DTC 26

DTC 26: Stoplight Switch System









CIRCUIT OPERATION
^ Battery positive voltage is supplied to the stoplight switch (terminal 2).
^ When the brake pedal is depressed, battery positive voltage is applied to the PCM (terminal 123). The PCM judges that the brake pedal is depressed and the stoplight switch is on when battery positive voltage is sensed at the PCM (terminal 123).

DTC SET CONDITIONS
If the stoplight switch is on for five minutes or more while driving 50 km/h (31 mph), it is judged there is a short circuit in the stoplight switch and diagnostic trouble code number "26" set?

TROUBLESHOOTING HINTS (The most likely causes for this code to be set:)
^ Malfunction of the stoplight switch circuit
^ Damaged harness, connector
^ Malfunction of the PCM

DIAGNOSIS

Required Special Tool: MB991502: Scan Tool (MUT-II)

STEP 1. Check the brake pedal height.
Q: Is the height adjusted properly?
YES: Go to Step 2.
NO: Adjust it.





STEP 2. Using scan tool MB991502, check data list item 26: Stoplight Switch.

CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.

1. Connect scan tool MB991502 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Set scan tool MB991502 to data reading mode for item 26, Stoplight Switch.
^ When the brake pedal is depressed, the display should be "ON."
^ When the brake pedal is not depressed, the display should be "OFF."
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the switch operating properly?
YES: This malfunction is intermittent.
NO: Go to Step 3.





STEP 3. Check the stoplight switch as single part.
Q: Is the switch normal?
YES: Go to Step 4.
NO: Replace the stoplight switch.





STEP 4. Check connector C-102 at stoplight switch for damage.
Q: Is the connector in good condition?
YES: Go to Step 5.
NO: Repair or replace it.

STEP 5. Check the switch output voltage at PCM connector C-114 by backprobing.





1. Do not disconnect connector C-114.





2. Measure the voltage between terminal 123 and ground by backprobing.
^ When the brake pedal is depressed, voltage should be battery positive voltage.
^ When the brake pedal is not depressed, voltage should be less than 1.0 volt.
Q: Is the voltage normal?
YES: Go to Step 8.
NO: Go to Step 6.








STEP 6. Check connectors C-114 at PCM, C-105 at joint connector and C-124, C-129 at intermediate connector for damage.
Q: Are the connectors in good condition?
YES: Go to Step 7.
NO: Repair or replace the defective connectors.








STEP 7. Check harness for damage between stoplight switch connector C-102 terminal 1 and PCM connector C114 terminal 123.
Q: Is the harness wire in good condition?
YES: Go to Step 9.
NO: Repair it.





STEP 8. Check connector C-114 at PCM for damage.
Q: Is the connector in good condition?
YES: Go to Step 9.
NO: Repair or replace it.





STEP 9. Using scan tool MB991502, check data list item 26: Stoplight Switch.

CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.

1. Connect scan tool MB991502 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Set scan tool MB991502 to data reading mode for item 26: Stoplight Switch.
^ When the brake pedal is depressed, the display should be "ON."
^ When the brake pedal is not depressed, the display should be "OFF."
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the switch operating properly?
YES: This malfunction is intermittent.
NO: Replace the PCM.