90 Quattro Sport V6-2.8L (AFC) (1995)
Vehicle Speed Sensor: Testing and Inspection
Checking Vehicle Speed Signal
CHECKING VEHICLE SPEED SIGNAL
REQUIREMENTS
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Speed display in instrument cluster OK
PROCEDURE
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Connect VAG 1551 Scan Tool and initiate Read Measuring Block Value
NOTE:
See On-Board Diagnostics, "Read Measuring Value Block" function 08, display group 003, display field 4. See: Testing and Inspection
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Switch ignition on.
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Lift left front of vehicle until wheel is raised off of floor.
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Rotate left front wheel by hand.
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Speed must be displayed on VAG 1551 scan tool
If NO speed is displayed:
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Switch ignition off and connect VAG 1598 test box with VAG 1598/11 adapter harness to ECM.
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Adapter harness for ECM connector B is not connected.)
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Connect US 1115 LED tester or equivalent across test box sockets 29 (signal) and 40 (positive).
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Switch ignition on.
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LED lights up at approx. half light intensity
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Turn left front wheel by hand.
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LED lights up brighter and begins blinking
If LED does not light up and blink:
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Check wiring for continuity between test box socket 29 and instrument cluster, using wiring diagram.
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If necessary, eliminate break in wiring between ECM connector B terminal 9 and instrument cluster.
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If wiring is OK, procede to troubleshooting charts for Vehicle Speed Signal. See: Troubleshooting Charts
If LED lights up and blinks:
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Switch ignition off and connect connector -B- of VAG 1598/11 adapter harness to ECM.
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If necessary, re-connect LED voltage tester to test box sockets 29 (signal) and 40 (positive).
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Switch ignition ON.
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LED must light up at approx. half light intensity
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Turn left front wheel slowly by hand.
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LED must light up brighter and begin blinking
If NOT:
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Even though no malfunction was found with connector -B- not connected to ECM, Replace ECM.