GM Service Manual Online
For 1990-2009 cars only

Circuit Description

Output driver modules (ODMs) are used by the powertrain control module (PCM) in order to turn on many of the current -- driven devices that are needed to control various engine and transaxle functions. DTC P1558 set indicates that an improper voltage level has been detected on the output circuit which controls the cruise control inhibit circuit.

Conditions for Running the DTC

    • The engine speed is 450 RPM or more.
    • System voltage is between 8 and 16 volts.

Conditions for Setting the DTC

    • The ignition is on.
    • The PCM detects an improper voltage level on the cruise inhibit signal circuit.
    • The condition exists for at least 30 seconds.

Action Taken When the DTC Sets

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

Conditions for Clearing the DTC

    • The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
    • The DTC can be cleared by using the scan tool's Clear DTC Information function.

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.

Test Description

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

  1. Normally, ignition positive voltage should be present on the control circuit with the PCM disconnected and the ignition turned ON.

  2. Tests for short to voltage on the control circuit.

  3. This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.

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 PCM harness connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Using a DMM connected to a good ground, measure the voltage of the cruise control inhibit signal circuit.

Does the voltage measure near the specified value?

B+

Go to Step 3

Go to Step 4

3

  1. Turn OFF the ignition.
  2. Disconnect the cruise control module.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the cruise control inhibit signal circuit with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

--

Go to Step 7

Go to Step 5

4

Test the cruise control inhibit signal circuit for a open, high resistance or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 6

5

Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 8

6

Inspect for poor connections at the harness connector of the cruise control module. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 9

7

Repair the short to voltage in the cruise control inhibit signal circuit.

Did you complete the repair?

--

Go to Step 10

--

8

Important: The replacement PCM must be programmed. Refer to Service Programming System (SPS) in Vehicle Control Systems.

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

Did you complete the replacement?

--

Go to Step 10

--

9

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

Did you complete the replacement?

--

Go to Step 10

--

10

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

Does the DTC reset?

--

Go to Step 2

System OK