GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The PCM removes the ground from the cruise control inhibit signal circuit when it determines that conditions exist for which cruise control should not be enabled. The PCM also monitors the voltage on this circuit in order to determine if a fault exists.

Conditions for Running the DTC

    • The engine speed is greater than 450 RPM.
    • The system voltage is between 8 volts and 16 volts.

Conditions for Setting the DTC

    • The PCM detects that an improper voltage exists on the cruise control inhibit circuit.
    • The above condition is present for at least 30 seconds.

Action Taken When the DTC Sets

The PCM stores the conditions which were present when the DTC set as Fail Records data only. This information is not stored as Freeze Frame data.

Conditions for Clearing the MIL/DTC

    • A history DTC clears after 40 malfunction free warm-up cycles.
    • The PCM receives a clear code command from the scan tool.

Step

Action

Value(s)

Yes

No

Schematic Reference: Cruise Control Schematics

1

Did you perform the Cruise Control Diagnostic System Check?

--

Go to Step  2

Go to Diagnostic System Check - Cruise Control

2

  1. Turn the ignition OFF.
  2. Disconnect the PCM.
  3. Turn the ignition ON, with the engine OFF.
  4. Measure the voltage of the cruise control inhibit signal circuit.

Does the voltage measure near the specified value?

B+

Go to Step 4

Go to Step 3

3

Test the cruise control inhibit signal circuit for an open, for a high resistance 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 8

Go to Step 5

4

Inspect for poor connections at the 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  8

Go to Step  6

5

Inspect for poor connections at the harness connector of the cruise control module. 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  8

Go to Step  7

6

Important:: Program the replacement PCM.

Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls-3.8L.

Did you complete the replacement?

--

Go to Step  8

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7

Replace the cruise control module. Refer to Cruise Control Module Replacement .

Did you complete the replacement?

--

Go to Step  8

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8

  1. Use the scan tool in order to clear the DTC.
  2. Operate the vehicle within normal cruise control operating conditions.

Does the DTC reset?

--

Go to Step 2

System OK