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2. Pull off plug I (18-pole) on the amplifier.
3. Check lead from plug II pin 14 to plug I pin 17 for short to B+.
Signal disturbance
Check lead from plug II pin 14 to plug I pin 17 for short with other leads.
Test point 5
Speedometer A, navigation unit
Open circuit/short to ground/short to B+
Fault code 24
Open circuit/short to ground/short to B+
1. Pull off plug on the navigation unit.
2. Pull off plug I on the instrument cluster.
3. Check lead from navigation unit plug pin 3 to plug I pin 13 for continuity and short to ground or short to B+.
NOTE:
The lead is routed via jumper plug 1 on relay carrier 1.
Test point 6
Signal, reverse gear-navigation unit
Signal implausible
Fault code 25
Signal implausible
1. Check reversing light switch or, on Tiptronic vehicles, position switch.
2. Check lead from navigation unit plug pin 4 to the reversing light switch or position switch for short circuit to B+.
NOTE:
The lead is routed via plug connection X 2/4 and via the jumper plug 20/1 on relay carrier 2.
Test point 7
Antenna, navigation unit
Open circuit
Fault code 26
Open circuit
1. Check whether plug connection of the antenna lead is securely locked.
2. Check whether plug connection of the antenna lead on the navigation unit is securely locked.
3. Check continuity of the antenna lead.
Test point 8
Data lead, PCM-instrument cluster
Short to ground
Short to B+
Fault code 27
Short to ground
1. Pull off plug I on the display and operator control unit.
2. Pull off plug III on the instrument cluster.
3. Check lead from plug I pin 20 to plug III pin 6 for short to ground.
Short to B+
1. Pull off plug I on the display and operator control unit.
2. Pull off plug III on the instrument cluster.
3. Check lead from plug I pin 20 to plug III pin 6 for short B+.
Test point 9
Data lead, instrument cluster-PCM
Open circuit/short to B+
This is a source reference. Confirm exact model applicability in the original material.