Vehicle Speed Sensor Operation

Control Module receives an AC voltage input from vehicle speed sensor that increases as speed increases. Control module uses this input to control current output to EVO actuator and to lower vehicle height at 65 MPH. As EVO output current increases, power steering assist decreases, which increases steering effort.

1. Confirm Control Module Speed Signal Acceptance
   
   Connect New Generation Star (NGS) tester or equivalent to diagnostic connector located on right shock tower. Route scan tool cable so vehicle can be driven with tester hooked up. Turn air suspension off, and enter Function Test No. 226. See FUNCTION TEST . Drive vehicle at speed greater than 10 MPH. Compare speeds displayed on scan tool and speedometer. If speeds displayed agree, go to DTC 35 . If speeds displayed do not agree, go to next step.
2. Check VSS Resistance
   
   Turn air suspension off. Disconnect vehicle speed sensor connector, located on transmission housing, at forward end of extension housing. See Figure. Measure resistance between terminals of vehicle speed sensor. If resistance is 180-240 ohms, connect vehicle speed sensor and go to next step. If resistance is not 180-240 ohms, replace vehicle speed sensor and repeat Auto Test.
3. Check Dark Green/White Wire For Short To Ground
   
   Disconnect air suspension/EVO steering control module harness connector C204 (Black). See Figure. Measure resistance between C204 pin No. 3 (Dark Green/White wire) and ground. If resistance is greater than 10 k/ohms go to next step. If resistance is less than 10 k/ohms, repair short to ground in Dark Green/White wire.
4. Check Continuity Of VSS Plus Circuit
   
   Measure resistance between C204 pin No. 3 (Dark Green/White wire) and Gray/Black wire (Dark Green/White wire on 1996 models) at speed sensor connector. If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open Dark Green/White or Gray/Black wires. Check system operation.
5. Check Continuity Of VSS Minus Circuit
   
   Measure resistance between C204 pin No. 23 and Pink/Orange wire (Gray/Red wire on 1996 models) at speed sensor connector. See Figure. If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open VSS minus circuit. See WIRING DIAGRAMS . Check system operation.
6. Check For Short Between VSS Plus & VSS Minus Circuits
   
   Ensure VSS is disconnected. Measure resistance between C204 pins No. 3 and 23. If resistance is less than 10 k/ohms, repair short circuit between VSS plus and VSS minus circuits. See WIRING DIAGRAMS . If resistance is greater than 10 k/ohms, replace air suspension/EVO steering control module. Check system operation.