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Home >> Porsche >> 2003 >> 911 Carrera 4S, Standard >> Repair and Diagnosis >> Brakes >> Anti-Lock Brakes >> Anti-Lock Brake System (Abs) - 5.3 & Abs/TC 5.3, Diagnosis - 911 CARRERA (996) >> Fault code 4340 - as of MY 2002 >> Stop light switch >> Diagnosis/troubleshooting

Stop light switch: Diagnosis/troubleshooting

DIAGNOSIS TROUBLESHOOTING - FAULT CODE 4340, AS OF MY 2002

Work instruction Display OK If not OK
1 Visual inspection
  • Check adjustment of the stop light switch
  • Check brake lights
Step 2
  • Readjust stop light switch, replace if necessary
  • Repair brake lights

-> End
2 Check stop light inputs in the control unit
  • In the Porsche System Tester II 9588, select the menu item Input signals and then the items Brake light and Brake pedal
  • Brake pedal released
Tester display:
  • Stop light off
  • Brake not actuated
Step 3
  • Observe tester display and slowly actuate the brake pedal at the same time
Tester display:
  • Stop light off
  • Brake actuated
Step 3
  • Continue observing tester display and slowly actuating the brake pedal at the same time
  • Stop light on
  • Brake actuated

Step 9
Step 3
3 Check stop light switch
  • Remove stop light switch
  • Measure resistance between pin 1 and pin 4
  Step 8
  • Stop light switch actuated
  • Measure resistance between pin 1 and pin 4
< 5
  • Stop light switch actuated
  • Measure resistance between pin 1 and pin 2
 
  • Disconnect stop light switch
  • Measure resistance between pin 1 and pin 2
< 5
Step 4
4 Check break circuit for short circuit to B+
  • Ignition off
  • Install stop light switch and connect plug
  • Pull plug off the PSM control unit
  • Ignition on
  • Brake pedal actuated
  • Measure voltage between PSM control unit plug pin 37 and ground
< 0.3 V
Step 5
Short circuit to B+ between the PSM control unit plug pin 37 and stop light switch pin 4
Repair wiring harness
-> End
5 Check break circuit for open circuit
  • Ignition on
  • Brake pedal not actuated
  • Measure voltage between PSM control unit plug pin 37 and ground
> 11 V
Step 6
Open circuit between the PSM control unit plug pin 37 and stop light switch pin 4
Repair wiring harness
-> End
6 Check make circuit for short circuit to B+
  • Ignition on
  • Brake pedal not actuated
  • Measure voltage between PSM control unit plug pin 32 and ground
< 0.3 V
Step 7
Short circuit to B+ between the PSM control unit plug pin 32 and stop light switch pin 2
Repair wiring harness
-> End
7 Check make circuit for open circuit
  • Ignition on
  • Brake pedal actuated
  • Measure voltage between PSM control unit plug pin 32 and ground
> 11 V
Step 9
Open circuit between the PSM control unit plug pin 32 and stop light switch pin 2
Repair wiring harness
-> End
8
  • Replace stop light switch
-> End
9
  • Replace PSM control unit
-> End