Test Description

The numbers below refer to the step numbers on the diagnostic table. See Fig 1 and Fig 2 .

1. 5
   
   The resistance measurement will not change if either the VSS high signal circuit or the VSS low signal circuit, but not both, is shorted to ground. The vehicle speed detector in the PCM and the VSS are matched in such a way that an open or a short to ground in the VSS low signal circuit will not usually cause a loss of speed signal or a DTC P0500 to set. The lower resistance value given represents the nominal resistance specification of the VSS at -40°C (-40°F), minus the manufacturing tolerance specification of 10 percent. The higher resistance value given represents the nominal resistance specification of the VSS at 150°C (302°F), plus the manufacturing tolerance specification of 10 percent.
2. 8
   
   This step isolates the short between the VSS and the wiring.
3. 10
   
   Do not skip Step 7. The DMM will detect AC voltage if the VSS high signal circuit is shorted to ground.
4. 13
   
   The replacement PCM must be programmed and the crankshaft position system variation procedure must be performed. Refer to the latest Techline procedures for PCM reprogramming and to POWERTRAIN CONTROL MODULE in SELF-DIAGNOSTICS - 4.3L article.

Fig 1: DTC P0500 Diagnostic Table (Steps 1-8)

Courtesy of GENERAL MOTORS CORP.

Fig 2: DTC P0500 Diagnostic Table (Steps 9-14)

Courtesy of GENERAL MOTORS CORP.