A3 Quattro V6-3.2L (BUB) (2008)
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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
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Multimeter.
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Wiring diagram.
Test requirements
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The Speedometer G21 OK.
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The Motronic Engine Control Module (ECM) J220 fuses OK.
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Battery voltage at least 12.5 volts.
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All electrical consumers such as, lights and rear window defroster, switched off.
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A/C switched off.
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Ground (GND) connections between engine/transmission/chassis OK.
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Ignition switched off.
Function test
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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, Check the vehicle speed:
Diagnostic text
Specified value
Vehicle Speed
Approx. Vehicle Speed
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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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Check the wiring from the Motronic Engine Control Module (ECM) J220 to the Instrument Cluster Control Module J285 for an open circuit, Short
to Battery (+), or to Ground (GND).
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Check the wiring connection for damage, corrosion, lose or broken terminals.
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If necessary, repair the faulty wiring connection.
Final procedures
After repair work, the following work steps must be performed in the following sequence:
1. Check the DTC memory. See: Powertrain Management/Computers and Control Systems/Testing and Inspection/Scan Tool Testing and
Procedures/Diagnostic Mode 03 - Read DTC Memory
2. If necessary, erase the DTC memory. See: Powertrain Management/Computers and Control Systems/Testing and Inspection/Scan Tool Testing
and Procedures/Diagnostic Mode 04 - Erase DTC Memory
3. If the DTC memory was erased, generate readiness code. See: Powertrain Management/Computers and Control Systems/Testing and
Inspection/Monitors, Trips, Drive Cycles and Readiness Codes
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End of diagnosis
