GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2000 🢒 Yukon XL - 2WD 🢒 Engine 🢒 Engine Controls - 4.8L, 5.3L, and 6.0L 🢒 Vehicle Speed Output Circuit Diagnosis

Object Number: 342030 Size: MF
Engine Controls Component Views
Cell 21: Body Control Module, Vehicle Speed Sensor
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

Various components apply a voltage to the vehicle speed output circuit. The powertrain control module (PCM) creates the vehicle speed output signal by rapidly grounding this circuit via an internal switch called a driver. The driver operates at the same rate as the vehical speed sensor (VSS) signal input. The various components recognize the voltage being pulled to ground as an indication of vehicle speed.

Diagnostic Aids

Important: Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing or replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.

For an intermittent, refer to Symptoms .

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Further circuit diagnosis may require I/P removal. Test the circuit from the PCM to the tachometer for being open, shorted to ground or, voltage.

    2.

  2. This step is testing for the proper signal voltage.

    3.

  3. This step is testing for an open circuit between the IPC and connector C100.

    4.

  4. This step is testing for a grounded circuit between the IPC and connector C100.

    5.

  5. This step is testing for an open circuit between the PCM and connector C100.

    6.

  6. This step is testing for a grounded circuit between the PCM and connector C100.

Step

Action

Value(s)

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

    Important: If the I/P is completely inoperative, refer to Instrument Cluster Inoperative in Instrument Panel, Gauges and Console.

  1. Raise the vehicles drive wheels. Refer to Lifting and Jacking the Vehicle in General Information.
  2. Start the engine.
  3. Place the transmission into drive for automatic transmission and third gear for manual transmission.
  4. Monitor the vehicle speed at the Instrument Panel Cluster (IPC).

Does the vehicle's speedometer indicate a vehicle speed?

--

Go to Diagnostic Aids

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Remove the underhood electrical center cover.
  3. Remove the underhood electrical center side shield.
  4. Lift the underhood electrical center up to gain access to C100 (16 way black) connector.
  5. Disconnect the C100 connector.
  6. Turn ON the ignition.
  7. Measure the vehicle speed output (4K) circuit voltage from the C100 connector (female side of connector) to ground using the DMM J 39200 .

Does the DMM display a voltage greater than the specified value?

9.5V

Go to Step 6

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Remove the IPC. Refer to Instrument Cluster Replacement in Instrument Panel, Gauges and Console.
  3. Test continuity from the vehicle speed output (4K) circuit at the IPC electrical connector to connector C100. Refer to Testing for Continuity in Wiring Systems.

Does the DMM display continuity?

--

Go to Step 5

Go to Step 8

5

Test continuity from the vehicle speed output (4K) circuit to battery ground.

Does the DMM display continuity?

--

Go to Step 9

Go to Diagnostic System Check - Instrument Cluster in Instrument Panel, Gauges and Console

6

  1. Turn OFF the ignition.
  2. Disconnect the PCM connector C2. Refer to Powertrain Control Module Replacement .
  3. Test the continuity of the vehicle speed output (4K) circuit from the PCM harness connector to connector C100 using the DMM J 39200 . Refer to Testing for Continuity in Wiring Systems.

Does the DMM display continuity.

--

Go to Step 7

Go to Step 10

7

Test the continuity of the vehicle speed output (4K) circuit from the PCM harness connector to ground using the DMM J 39200 .

Does the DMM display continuity?

--

Go to Step 11

Go to Step 12

8

Repair the open vehicle speed output (4K) circuit from the IPC to connector C100. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

System OK

--

9

Important: If you cannot locate a grounded circuit, disconnect each component (one at a time) and see if the grounded condition is caused by a component on the vehicle speed output (4K) circuit.

Repair the grounded vehicle speed output (4K) circuit from the IPC to connector C100. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

System OK

--

10

Repair the open vehicle speed output (4K) circuit from the PCM to C100. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

System OK

--

11

Repair the grounded vehicle speed output (4K) circuit from the PCM to C100. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

System OK

--

12
  1. Inspect the PCM harness connector for poor connections. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. If you find a poor connection repair the connection as necessary. Refer to Connector Repairs in Wiring Systems.

Did you find and repair the condition?

--

System OK

Go to Step 13

13

Important:: Program the replacement PCM. Refer to Powertrain Control Module Replacement .

Replace the PCM.

Is the replacement complete?

--

System OK

--