GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The powertrain control module (PCM) monitors system voltage on the PCM ignition feed circuit. If the system voltage is out of tolerance, DTC P0560 will be set. When the conditions that set DTC P0560 are present, operation of some vehicle systems and components may be affected.

Conditions for Running the DTC

The engine is running at more than 650 RPM.

Conditions for Setting the DTC

    • The system voltage monitored at the PCM ignition feed circuit is less than 9.0 volts or more than 16.0 volts.
    •  The above conditions are present for more than 25 seconds.

Action Taken When the DTC Sets

    • The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.
    • The PCM will store conditions which were present when the DTC set as Freeze Frame/Failure Records data.

Conditions for Clearing the MIL/DTC

    • The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has run and passed.
    • The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
    • The DTC can be cleared by using a scan tool.

Diagnostic Aids

Inspect for the following conditions:

A poor connection or a damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, observe the Ignition 1 voltage display on the scan tool while moving the connectors and the wiring related to the PCM, the dash harness, and the engine harness. A change in the display indicates the location of the fault.

If DTC P0560 cannot be duplicated, 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.

Refer to the following procedures in Wiring Systems:

    •  Testing for Continuity
    •  Testing for Intermittent Conditions and Poor Connections
    •  Connector Repairs
    •  Repairing Connector Terminals

For complete information and additional diagnostics for the vehicle charging system, refer to Charging System Description in Engine Electrical.

Step

Action

Values

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

Is DTC P1635 also set?

--

Go to DTC P1635 5 Volt Reference Circuit

Go to Step 3

3

  1. Start and run the engine at more than 1000 RPM.
  2. Observe Ignition 1 on the scan tool.

Is the Ignition 1 voltage within the specified range?

10.0-16.0 V

Go to Step 4

Go to Step 5

4

  1. Review and record the scan tool Failure Records data.
  2. Clear the DTC P0560 and operate the vehicle within the Failure Records conditions.
  3. Using a scan tool, monitor the Specific DTC info for DTC P0560 until the DTC P0560 test runs.
  4. Note the test result.

Does the scan tool indicate the DTC failed this ignition?

--

Go to Step 5

Go to Diagnostic Aids

5

  1. Install a digital multimeter (DMM) between the battery terminals.
  2. Monitor the DMM while running the engine at more than 1000 RPM.

Does the DMM indicate the battery voltage is within the specified range?

10.0-16.0 V

Go to Step 6

Go to Step 7

6

  1. Load the electrical system by turning on the headlamps and the HVAC high blower.
  2. Monitor the DMM while running the engine at more than 2000 RPM.

Does the DMM indicate the battery voltage is within the specified range?

10.0-16.0 V

Go to Step 8

Go to Step 7

7

  1. Turn OFF the ignition and disconnect the generator electrical connector.
  2. Turn ON the ignition.
  3. Use a DMM in order to measure the voltage between the generator control circuit at the generator harness connector and ground.
  4. Command the GEN L Term on using the scan tool.

Is the voltage near the specified value with the GEN L Term commanded on?

5.0 V

Go to Step 12

Go to Step 10

8

Compare the Ignition 1 voltage displayed on the scan tool with the actual battery voltage indicated by the DMM.

Does the scan tool Ignition 1 value closely match the actual value indicated by the DMM?

--

Go to Diagnostic Aids

Go to Step 9

9

  1. Test the PCM ignition feed circuit for a poor connection between the ignition switch and the PCM. Refer to Wiring Repairs in Wiring Systems.
  2. If a problem is found, replace the faulty terminals.

Was a problem found?

--

Go to Step 14

Go to Step 13

10

  1. Test the generator control circuit for an open or a short to ground between the PCM and the generator.
  2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a problem found?

--

Go to Step 14

Go to Step 11

11

  1. Test the generator control circuit for a poor terminal connection at the PCM.
  2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a problem found?

--

Go to Step 14

Go to Step 13

12

  1. Test the generator control circuit for a poor terminal connection at the generator.
  2. If a problem is found repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a problem found?

--

Go to Step 14

Go to Diagnostic System Check - Engine Electrical in Engine Electrical

13

Important: : The replacement PCM must be programmed.

Replace the PCM. Refer to Powertrain Control Module Replacement/Programming .

Is the action complete?

--

Go to Step 14

--

14

  1. Clear the DTCs.
  2. Start and run the engine at more than 1000 RPM.
  3. Observe the Ignition 1 display on the scan tool.

Is Ignition 1 voltage between the specified values?

10.0-16.0 V

System OK

Go to Step 2