24-168
Vehicle speed signal, checking
Notes:
The vehicle speed signal is generated by the
Vehicle Speed Sensor (VSS) -G68- (at
transmission) and processed in the instrument
cluster.
The processed signal enters at terminal 54 of
the ECM and is used for idle stabilization and
tip-in shock reduction during shifting.
Test requirement:
Function and display of speedometer OK.
Troubleshooting:
Electrical Wiring Diagrams, Troubleshooting &
Component Locations binder
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24-175
A/C system signal, checking
The A/C system signal notifies the Engine
Control Module (ECM), that the A/C system
requires a higher idle speed to achieve the
desired interior temperature (regardless of
whether heating or cooling is required).
The increase in idle speed based on presence of
the A/C system signal is control module
dependent and occurs only in vehicles with All
Wheel Drive (AWD) and manual transmission.
Test sequence
- Connect VAS5051 tester or VAG1551 scan tool
and select the control module for engine
electronics using "address word" 01 Page 01
-
9 .
Engine must run at idle for this.Rapid data transfer
HELP
Select function XX
When indicated on display:
- Press buttons -0- and -8- to select "Read Measuring Value Block" and
press -Q- button to confirm input.
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