Trouble Code 54 Stop Light Switch Signal Circuit Malfunction - Stop Light Switch Signal Circuit Malfunction

DIAGNOSIS: 

• Faulty stop light switch

TROUBLE SYMPTOM: 

• ABS does not operate.

WIRING DIAGRAM: 

Fig 1: Wiring Diagram

1. 10AF1: CHECK OUTPUT OF STOP LIGHT SWITCH USING SELECT MONITOR. 
   1. Select "Current data display & Save" on the select monitor.
   2. Release the brake pedal.
   3. Read the stop light switch output in the select monitor data display.

   CHECK: Is the reading indicated on monitor display less than 1.5 V? 

   1. YES:  Go to step 10AF2. 
   2. NO:  Go to step  10AF3: CHECK IF STOP LIGHTS COME ON .
2. 10AF2: CHECK OUTPUT OF STOP LIGHT SWITCH USING SELECT MONITOR. 
   1. Depress the brake pedal.
   2. Read the stop light switch output in the select monitor data display.

   CHECK: Is the reading indicated on monitor display between 10 and 15 V? 

   1. YES:  Go to step  10AF5: CHECK POOR CONTACT IN CONNECTORS .
   2. NO:  Go to step 10AF3. 
3. 10AF3: CHECK IF STOP LIGHTS COME ON. 

   Depress the brake pedal.

   CHECK: Do stop lights turn on? 

   1. YES:  Go to step 10AF4. 
   2. NO:  Repair stop lights circuit.
4. 10AF4: CHECK OPEN CIRCUIT IN HARNESS. 
   1. Turn ignition switch to OFF.
   2. Disconnect connector from ABSCM & H/U.
   3. Depress brake pedal.
   4. Measure voltage between ABSCM & H/U connector and chassis ground.

   Connector & terminal 

   1. (F49) No. 2 - Chassis ground: 
   Fig 2: Measuring Voltage Between ABSCM & H/U Connector & Chassis Ground

   

   CHECK: Is the voltage between 10 and 15 V? 

   1. YES:  Go to step 10AF5. 
   2. NO:  Repair harness between stop light switch and ABSCM & H/U connector.
5. 10AF5: CHECK POOR CONTACT IN CONNECTORS. 

   CHECK: Is there poor contact in connector between stop light switch and ABSCM & H/U? 

   1. YES:  Repair connector.
   2. NO:  Go to step 10AF6. 
6. 10AF6: CHECK ABSCM & H/U. 
   1. Connect all connectors.
   2. Erase the memory.
   3. Perform inspection mode.
   4. Read out the trouble code.

   CHECK: Is the same trouble code as in the current diagnosis still being output? 

   1. YES:  Replace ABSCM & H/U, see ABS CONTROL MODULE AND HYDRAULIC CONTROL UNIT (ABSCM & H/U)  .
   2. NO:  Go to step 10AF7. 
7. 10AF7: CHECK ANY OTHER TROUBLE CODES APPEARANCE. 

   CHECK: Are other trouble codes being output? 

   1. YES:  Proceed with the diagnosis corresponding to the trouble code.
   2. NO:  A temporary poor contact.