GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The PCM grounds the cruise control inhibit signal circuit when it determines that conditions exist for which cruise could 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 ignition is ON.
    • The system voltage is between 9-16 volts.

Conditions for Setting the DTC

    • The PCM detects that an improper voltage exists on the cruise control inhibit signal circuit.
    • The above condition is present 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 which were present when the DTC set as Failure 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.

Diagnostic Aids

Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

DTC P1585 -- Cruise Control Inhibit Control Circuit

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 OFF the ignition.
  2. Disconnect the C103.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage on the cruise control inhibit signal circuit on the male terminal side of C103.

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 between C103 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 C103 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 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

Important:: Program the replacement PCM.

Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls-3.4 L.

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 DTC.
  2. Operate the vehicle within the Conditions for Running the DTC.

Does the DTC reset?

--

Go to Step  2

System OK