GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 HUMMER 🢒 2004 🢒 H2 🢒 DTC 🢒 DTC P0608

Circuit Description

The powertrain control module (PCM) creates the vehicle speed output signal by pulsing the circuit to ground. The PCM monitors the voltage on the vehicle speed output circuit. If the PCM determines that the voltage is out of the normal operating range, a DTC sets.

Conditions for Running the DTC
    • The engine speed is more than 400 RPM.
    • The ignition voltage is between 6.0-18.0 volts.

Conditions for Setting the DTC
    • The PCM detects that the commanded state of the driver and the actual state of the signal circuit do not match.
    • The above condition must be present for a minimum of 5 seconds.

Action Taken When the DTC Sets

The PCM records the operating conditions at the time the diagnostic fails. The PCM displays the failure information in the Failure Records on the scan tool.

Conditions for Clearing the MIL/DTC
    • The history DTC clears after 40 malfunction free warm-up cycles.
    • The DTC becomes history when the conditions for setting the DTC are no longer present.
    • The PCM receives the clear code command from the scan tool.

Step

Action

Value(s)

Yes

No

Schematic Reference: Instrument Cluster Schematics

1

Did you perform the instrument panel cluster (IPC) Diagnostic System Check?

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Go to Step 2

Go to Diagnostic System Check - Instrument Cluster

2
  1. Install a scan tool.
  2. Raise the vehicles 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 a manual transmission.
  5. With the scan tool, observe the Vehicle Speed Sensor parameter in the powertrain control module (PCM) Engine Data 1 data list.

Does the Vehicle Speed Sensor parameter match the speedometer display?

--

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3
  1. Turn OFF the ignition.
  2. Disconnect the PCM connector C2.
  3. Turn ON the ignition, 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 5

4

Test the vehicle speed signal circuit for a short to battery voltage. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 6

5

Test the vehicle speed signal circuit for an open, for a short to voltage, or for a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 7

6

Inspect for poor connections at harness connector of the PCM. 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 10

Go to Step 8

7

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 10

Go to Step 9

8

Important: Program the replacement PCM.

Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls-6.0L (LQ4).

Did you complete the replacement?

--

Go to Step 10

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9

Replace the IPC. Refer to Instrument Cluster Replacement .

Did you complete the replacement?

--

Go to Step 10

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10
  1. Use the scan tool in order to clear the DTCs.
  2. Operate vehicle within the Conditions for Running this DTC.

Does the DTC reset?

--

Go to Step 2

System OK