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 ignition is ON.
    • 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 signal circuit.
    • The condition exists for at least 30 seconds.

Action Taken When the DTC Sets

    • The PCM does not illuminate the malfunction indicator lamp (MIL).
    • The PCM stores the conditions present when the DTC set as Failure Records data only.

Conditions for Clearing the DTC

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

Diagnostic Aids

In order to determine whether an improper voltage level exists on the output circuit, the PCM compares the voltage level to the commanded state.

If the condition is intermittent, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

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 C101.
  3. Turn the ignition ON, with the engine OFF.
  4. Measure the voltage on the cruise control inhibit signal circuit.

Does the voltage measure near the specified value?

B+

Go to Step 3

Go to Step 4

3

Test the cruise control inhibit signal circuit for an open, for a high resistance or for a short to ground between C101 and the cruise control module. 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

4

Test the cruise control inhibit signal circuit for an open, for a high resistance, or for a short to ground between C101 and the PCM. 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

5

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 9

Go to Step 7

6

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

7

Important: Program replacement PCM.

Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls - 3.1L or Powertrain Control Module Replacement in Engine Controls - 3.8L.

Did you complete the replacement?

--

Go to Step 9

--

8

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

Did you complete the replacement?

--

Go to Step 9

--

9

  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within.

Does the DTC reset?

--

Go to Step 2

System OK