Signal Too Low

Signal too low

Checking the connectors
Check the connectors on the upper electronic module and rear reading lamp unit for contact resistance and oxidation as described in Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault , and for a loose contact as described in Checking wiring and terminals. Intermittent faults Checking Wiring and Terminals. Intermittent Faults.

Additional information:
- For information on signals and additional values, see Signal specification Signal Specification, Upper Electronic Module (UEM).
- To connect the test box, see Connecting the breakout box Connecting the Breakout Box.









Is there a fault?

Yes - Verification

No - Checking for open circuits and short circuits

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Checking for open circuits and short circuits
Check the wire between the upper electronic module and the control unit of the rear reading lamp unit for a short circuit to ground, as described in Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Remove the connector from the roof lamp unit and measure between the connector and the UEM as described below.

UEM-0030 Rear left reading lamp
Control unit #20 and reading lamp unit #1.

UEM-0032 Rear right reading lamp
Control unit #20 and reading lamp unit #7.
Check the wire between the upper electronic module and the control unit of the rear reading lamp unit for an open circuit, as described in Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.

UEM-0030 Rear left reading lamp
Control unit #7 and reading lamp unit #1.

UEM-0032 Rear right reading lamp
Control unit #17 and reading lamp unit #7.
If a fault is found, replace the wire.
If the wire is OK, test with a new bulb.

Additional information:
- For information on signals and additional values, see Signal specification Signal Specification, Upper Electronic Module (UEM).
- To connect the test box, see Connecting the breakout box Connecting the Breakout Box.
- To replace the bulb, see Bulb, reading lamp, rear, replacing Bulb, Reading Lamp, Rear, Replacing.










Continue - Verification

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Verification




Verification

Verification

Hint: After carrying out the repair, check that the fault has been remedied.








- Ignition off.
- Reinstall the connectors, components etc.
- Ignition on.
Check that the relevant lamp button and lamp are functioning.

Does the lamp function?

Yes - VERIFIED

No - VERIFICATION FAILED

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VERIFIED - Fault Found

VERIFICATION FAILED - Trouble-shooting information

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Trouble-shooting 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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Attempt New Test - Checking the connectors

FAULT-TRACING FAILED - No Fault Found

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