Checking Low Beam
Checking low beam
Checking the signal from the lighting switch
- Ignition on.
Turn the lighting switch to position 2. Read off the signal from the lighting switch. The value must be Position 2.
Is the value Position 2?
Yes - Checking the wiring and component
No - Checking the wiring and component
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Checking the wiring and component
- Ignition off.
Check the cable between control module connector P terminal #17 (#B37) and connector terminal #9 for the lighting switch. Check the cable between control module connector P terminal #18 (#B38) and connector terminal #13 for the lighting switch. Check for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault. Check for contact resistance and oxidation according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Try a new switch if no fault is found in the cables.
Remedy as necessary.
Other information
- 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 Signal Description. Central Electronic Module (CEM)
- To access or replace the switch, see Replacing rocker switch Replacing Rocker Switch.
Continue - Verification
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Checking the wiring and component
- Ignition off.
Check that fuses 21 and 22 in the integrated relay / fusebox in the engine compartment are intact.
Check that the bulbs for low beam are intact (does not apply to cars with Xenon lamps).
Check the cable between fuse 21 and control module connector F terminal #3 (#B3). Check the cable between fuse 22 and control module connector F terminal #13 (#B13). Check the cable between control module connector F terminal #4 (#B4) and the left low beam terminal #2 (for Xenon lamps the cable between terminal F#4 (B#4) and the driver connector for Xenon lamps). Check the cable between control module connector F terminal #12 (#B12) and the right low beam terminal #2 (for Xenon lamps the cable between terminal F#12 (B#12) and the driver connector for Xenon lamps). Check these cables for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault. Check for contact resistance and oxidation according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault. Check for a short-circuit to ground Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Check the ground leads from each low beam lamp. Check for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault. Check for contact resistance and oxidation according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Remedy as necessary.
Other information
- 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 Signal Description. Central Electronic Module (CEM)
- To access or replace the relay or fuse, see the inside of the cover on the engine compartment relay/fusebox or the wiring diagram.
Continue - Verification
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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.
Activate low beam. Low bean must both light and go out.
Does low beam light and go out?
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 - Exit fault-tracing
No - Attempt New Test
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Attempt New Test - Checking the signal from the lighting switch
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