A6 Sedan V6-3.2L (BKH) (2007)
Vehicle Speed Sensor: Testing and Inspection
Speed Signal, Checking
The following procedure requires a test drive. Observe all Safety Precautions.
Special tools, testers and auxiliary items required
‹› Multimeter.
‹› Wiring diagram.
Test requirement
‹› The function and display of the Speedometer OK.
‹› The Engine Control Module (ECM) (J623) fuses OK.
‹› Battery voltage at least 12.5 V.
‹› All electrical consumers such as, lights and rear window defroster, switched off.
‹› A/C switched off.
‹› Ground (GND) connections between engine/transmission/chassis OK.
‹› Ignition switched off.
Test procedure
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Perform a preliminary check to verify the customer's complaint. Refer to => [ Preliminary Check ] See: Computers and Control Systems/Testing
and Inspection/Scan Tool Testing and Procedures/Preliminary Check.
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Connect the scan tool.
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Perform a road test with a vehicle speed greater than 5 Km/h.
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Using the scan tool, have an assistant observe the reading on the display:
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Compare the vehicle speed on the scan tool to the Speedometer (G21).
Specified value: a difference of no greater than 10%.
If the specified value was not obtained or no speed was displayed:
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End the diagnosis and switch ignition off.
If no speed is displayed:
The speed signal is transferred from the Engine Control Module (ECM) (J623) to the instrument cluster through the wire connection or through the
CAN-Bus, depending on version.
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Check the wiring connections.
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Check the terminal resistance for CAN-Bus Refer to => [ Can-Bus Terminal Resistance, Checking ] See: Computers and Control Systems/Testing
and Inspection/Component Tests and General Diagnostics/Component Tests (SAE Code Tests)/CAN-Bus Terminal Resistance, Checking
After repair work, the following work steps must be performed in the following sequence:
1. Check the DTC memory. Refer to => [ Diagnostic Mode 03 - Read DTC Memory ] See: Computers and Control Systems/Testing and
Inspection/Scan Tool Testing and Procedures/Diagnostic Modes 01 - 09/Diagnostic Mode 03 - Read DTC Memory.