Speedometer and/or Odometer Inaccurate or Inoperative. Chevrolet Chevy C Cab/Chassis HD (GMT 400) 2001

GM Service Manual Online

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 2001 🢒 Chevy C Cab/Chassis HD (GMT 400) 🢒 Body and Accessories 🢒 Instrument Panel, Gauges, and Console 🢒 Speedometer and/or Odometer Inaccurate or Inoperative

Speedometer and/or Odometer Inaccurate or Inoperative 8.1L Gasoline Engine

Step	Action	Yes	No
Schematic Reference: Instrument Cluster Schematics
1	Did you perform the Instrument Cluster Diagnostic System Check?	Go to Step 2	Go to Diagnostic System Check - Instrument Cluster
2	Install a scan tool. Raise the vehicle drive wheels. Refer to Lifting and Jacking the Vehicle in General Information. Start the engine. Place the transmission into drive for an automatic transmission or third gear for a manual transmission. With the scan tool, observe the Vehicle Speed Sensor parameter in the PCM Engine Data 1 data list. Does the Vehicle Speed Sensor parameter match the speedometer display?	Go to Step 3	Go to Step 4
3	Does the odometer operate properly?	Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems	Go to Step 6
4	Test the vehicle speed signal circuit for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 7	Go to Step 5
5	Inspect for poor connections at the harness connector of the IPC. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 7	Go to Step 6
6	Replace the IPC. Refer to Instrument Cluster Replacement . Did you complete the replacement?	Go to Step 7	--
7	Operate the system in order to verify the repair. Did you correct the condition?	System OK	Go to Step 2

Speedometer and/or Odometer Inaccurate or Inoperative L65 Diesel Engine

Step	Action	Yes	No
Schematic Reference: Instrument Cluster Schematics
1	Did you perform the Instrument Cluster Diagnostic System Check?	Go to Step 2	Go to Diagnostic System Check - Instrument Cluster
2	Install a scan tool. Raise the vehicle's drive wheels. Refer to Lifting and Jacking the Vehicle in General Information. Start the engine. Place the transmission in drive for automatic transmission and third gear for manual transmission. With the scan tool, observe the Vehicle Speed Sensor parameter in the PCM Engine Data 1 data list. Does the Vehicle Speed Sensor parameter match the speedometer display?	Go to Step 4	Go to Step 3
3	Test the vehicle speed signal circuit between S221 and the IPC for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 9	Go to Step 5
4	Test the vehicle speed signal circuit for a short to ground, for an open, or for a short to voltage between the PCM and the VSS buffer, between the overspeed alarm and S211, and between the IPC and S211. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 9	Go to Step 6
5	Inspect for poor connections at the harness connector of the IPC. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 9	Go to Step 7
6	Inspect for poor connections at the harness connector of the VSS buffer. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 9	Go to Step 8
7	Replace the IPC. Refer to Instrument Cluster Replacement . Did you complete the replacement?	Go to Step 9	--
8	Replace the VSS buffer. Refer to Vehicle Speed Sensor Module Replacement . Did you complete the replacement?	Go to Step 9	--
9	Operate the system in order to verify the repair. Did you correct the condition?	System OK	Go to Step 2