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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 958 (Instrument Panel System Displays, Gauges And Console) >> Diagnostic Information and Procedures >> DTC P0608: Vehicle Speed Output Circuit >> Diagnostic Aids

Diagnostic Aids

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
IMPORTANT: Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing/replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.

Using Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can aid in determining how many miles since the DTC set. The Fail Counter and Pass Counter can also aid determining how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This will isolate when the DTC failed.

For an intermittent, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

DTC P0608

Step Action Value(s) Yes No
Schematic Reference: Instrument Cluster Schematics 
Connector End View Reference: Master Electrical Component List
1 Did you perform the Instrument Cluster Diagnostic System Check? - Go to Step 2  Go to Diagnostic System Check - Instrument Cluster 
2
  1. Turn the ignition OFF.
  2. Raise the vehicle drive wheels. Refer to Lifting and Jacking the Vehicle in General Information.
  3. Start the engine.
  4. Place the transmission into drive for an automatic transmission or third gear for manual transmission.
Does the vehicle speedometer indicate a vehicle speed?		 - Go to Diagnostic Aids Go to Step 3 
3
  1. Turn the ignition OFF.
  2. Disconnect the PCM connector C2.
  3. Turn the ignition ON, with the engine OFF.
  4. Measure the voltage from the vehicle speed signal circuit of the PCM to a good ground.
Does the voltage measure greater than the specified value?		 9.5 V Go to Step 4  Go to Step 6 
4 Test the vehicle speed signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 8  Go to Step 5 
5 Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 8  Go to Step 7 
6 Repair the short to ground in the vehicle speed signal circuit. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 8  -
7
IMPORTANT: Program the replacement PCM.
Replace the PCM. Refer to the following procedures:Did you complete the replacement?		 - Go to Step 8  -
8
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Does the DTC reset?		 - Go to Step 2  System OK
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