Signal Too Low

Signal too low

Checking for a short-circuit
Check whether the switch for the third row reading lamps has jammed in the depressed position.
Check the signal cable for buttons between the upper electronic module (UEM) terminal #A2 and the switch which is connected to the third row reading lamps. Check for a short-circuit to ground.
Disconnect connectors for the reading lamp module and the upper electronic module (UEM). Measure the resistance over the signal cable between the connectors. If the cable is short-circuited to ground, 0 ohms will be measured.
Remedy as necessary.

Other information:
- To connect the breakout box, see Connecting the breakout box Connecting the Breakout Box
- To access or replace the reading lamp module, see Bulb, reading lamp, rear, replacing Bulb, Reading Lamp, Rear, Replacing
- For information about signals, see Signal specification Signal Specification, Upper Electronic Module (UEM)
- To access the connector for the upper electronic module (UEM), see Upper electronic module (UEM)/rearview mirror, replacing Upper Electronic Module (UEM)/Rearview Mirror, Replacing
- To fault-trace wiring and terminals, see Checking wiring and terminals Checking Wiring and Terminals.





Was a fault detected?

Yes - Verification

No - No Fault Found

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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 - Troubleshooting procedure complete

No - Fault-tracing information

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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 - Exit Fault-tracing

No - Attempt New Test

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Attempt New Test - Checking for a short-circuit

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