Signal Too High / Signal Missing
Signal too high / Signal missing
Checking the function
- Ignition off.
Check whether the fault is due to the ignition switch lighting or the high level stop lamp.
Note! High level stop lamp applies only to S60/S80. For other models this is powered by the rear electronic module (REM).
The ignition switch lighting comes on when the car is unlocked and goes out when the car is locked or the engine is running.
The high level stop lamp must light when the brake pedal is depressed and go out when the pedal is released.
Select the function to be fault-traced.
- 1. Ignition switch lighting
- 2. High level stop lamp.
Select an alternative.
1 - Checking the ignition switch lighting
2 - Checking the high level stop lamps
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Checking the ignition switch lighting
- Ignition off.
Check that the bulb is intact.
Check the connectors for the central electronic module (CEM) and ignition switch lighting. Check for contact resistance and oxidation. Check for loose connections. Check for damage carefully.
Check the power supply cable between central electronic module (CEM) terminal #19D (#B19) and ignition switch lighting terminal #5. Check for an open-circuit. Check for a short-circuit to supply voltage.
Check the ground lead between ignition switch terminal #6 and the ground terminal. Check for an open-circuit. Check for a short-circuit to supply voltage.
Remedy as necessary.
Other information
- To access the bulb and connector for the ignition switch, see Bulb, ignition switch, replacing Service and Repair
- To access the central electronic module (CEM), see Central electronic module (CEM), replacing Central Electronic Module (CEM), Replacing
- To connect the breakout box, see Connecting the breakout box Connecting the Breakout Box, Central Electronic Module (CEM)
- For information about signals, see Signal specification Pinout Values and Diagnostic Parameters
- Checking wiring and terminals Checking Wiring And Terminals
- For further information about the cables and ground terminals, see the Wiring Diagram.
Continue - Information
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Checking the high level stop lamps
- Ignition off.
Check the central electronic module (CEM) and the high-mounted stop lamp connectors. Check for contact resistance and oxidation. Check for loose connections. Check for damage carefully.
Check the power supply cable between central electronic module (CEM) terminal #5B (#A25) and brake light connector terminal #1. Check for an open-circuit. Check for a short-circuit to supply voltage.
Check the ground lead between brake light connector terminal #5 and the ground terminal. Check for an open-circuit. Check for a short-circuit to supply voltage.
Try a new brake light if no faults were found.
Remedy as necessary.
Other information:
- To access / replace the high mounted stop lamp, see Stop lamp, rear windshield, replacing Stop Lamp, Rear Windshield, Replacing
- To access the central electronic module (CEM), see Central electronic module (CEM), replacing Central Electronic Module (CEM), Replacing
- To connect the breakout box, see Connecting the breakout box Connecting the Breakout Box, Central Electronic Module (CEM)
- For information about signals, see Signal specification Pinout Values and Diagnostic Parameters
- Checking wiring and terminals Checking Wiring And Terminals
- For further information about the cables and ground terminals, see the Wiring Diagram.
Continue - Information
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Information
Verification
Verification
Hint: After the repair it is necessary to check that the fault has been rectified.
- Ignition off.
- Connect the connectors, install the components, etc.
- Ignition on.
Read the diagnostic trouble codes.
If diagnostic trouble code has changed to intermittent status this indicates that the fault is no longer activated.
Is the diagnostic trouble code intermittent?
Yes - VERIFIED
No - VERIFICATION FAILED
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VERIFICATION FAILED - Fault-tracing information
VERIFIED - Fault Found
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Fault-tracing information
Information
Fault-tracing information
The fault should have been detected and remedied. As this is not the case fault-tracing has failed.
Exit fault-tracing for this diagnostic trouble code (DTC) or make another attempt.
Do you want to exit fault-tracing?
Yes - FAULT-TRACING FAILED
No - Attempt New Test
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FAULT-TRACING FAILED - No Fault Found
Attempt New Test - Checking the function
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