GM Service Manual Online
For 1990-2009 cars only

Object Number: 388523  Size: MF
Cell 20: Power, Ground, MIL, and DLC
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The 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.

Conditions for Setting the DTC

    •  System voltage monitored at the PCM ignition feed circuit is below 10.0 volts or above 16.0 volts.
    •  Above conditions for longer than 5 seconds.

Action Taken When the DTC Sets

    • The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
    • The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure.
    • The PCM writes the conditions to the Freeze Frame and updates the Failure Records.

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

Check for the following conditions:

Important: :  Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.

    •  Poor terminal connection.
         Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Use a corresponding mating terminal to test for proper tension. Refer to Intermittents and Poor Connections Diagnosis , and Connector Repairs Wiring Systems.
    •  Damaged harness.
         Inspect the wiring harness for damage. If the harness appears to be OK, observe the sensor display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the sensor display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems.
    •  Inspect the PCM and the engine grounds for clean and secure connections.

If the DTC is determined to be intermittent, reviewing the Fail Records can be useful in determining when the DTC was last set.

  1. 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

1

Was the Powertrain on Board Diagnostic System Check performed?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

Is DTC P1635 5 Volt Reference Circuit also set?

--

Go to DTC P1635 5 Volt Reference Circuit

Go to Step 3

3

  1. Start and run engine above 1000 RPM.
  2. Observe Ignition 1 on the scan tool data list.

Is Ignition 1 voltage between the specified values?

10.0-16.0V

Go to Step 4

Go to Step 5

4

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

Does scan tool indicate DTC failed this ignition?

--

Go to Step 5

Go to Diagnostic Aids

5

  1. Install a J 39200 DMM between the battery terminals.
  2. Monitor the J 39200 DMM while running the engine above 1000 RPM.

Does J 39200 DMM show battery voltage between the specified values?

10.0-16.0V

Go to Step 6

Go to Step 7

6

  1. Load electrical system by turning on the headlamps and the HVAC high blower.
  2. Monitor the J 39200 DMM while running the engine above 2000 RPM.

Does J 39200 DMM show battery voltage between the specified values?

10.0-16.0V

Go to Step 8

Go to Step 7

7

  1. Turn the ignition off and disconnect the generator electrical connector.
  2. Turn the ignition on.
  3. Connect a J 39200 DMM to measure voltage between the Generator Control circuit at the generator harness connector and ground.
  4. Command the GEN L Term on using the scan tool.

Does the J 39200 DMM display voltage near the specified value with the GEN L Term. commanded on?

5.0V

Go to Step 12

Go to Step 10

8

Compare the Ignition 1 voltage displayed on the scan tool with the actual battery voltage read with the J 39200 DMM.

Does the scan tool Ignition 1 value closely match the actual value read with the J 39200 DMM?

--

Go to Diagnostic Aids

Go to Step 9

9

  1. Check the PCM ignition feed circuit for a poor connection between the ignition switch and the PCM.
  2. If a problem is found, replace faulty terminal(s). Refer to Testing for Continuity , Intermittents and Poor Connections Diagnosis , Repairing Connector Terminals and Connector Repairs .

Was a problem found?

--

Go to Step 14

Go to Step 13

10

  1. Check 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 .

Was a problem found?

--

Go to Step 14

Go to Step 11

11

  1. Check the Generator Control circuit for a poor terminal connection at the PCM.
  2. If a problem is found, repair as necessary. Refer to Testing for Continuity , Intermittents and Poor Connections Diagnosis , Repairing Connector Terminals , and Connector Repairs .

Was a problem found?

--

Go to Step 14

Go to Step 13

12

  1. Check the Generator Control circuit for a poor terminal connection at the generator.
  2. If a problem is found, repair as necessary . Refer to Testing for Continuity , Intermittents and Poor Connections Diagnosis , Repairing Connector Terminals , and Connector Repairs .

Was a problem found?

--

Go to Step 14

Go to Charging System Check

13

Important: :  Replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming .

Replace the PCM.

Is the action complete?

--

Go to Step 14

--

14

  1. Clear DTCs.
  2. Start and run engine above 1000 RPM.
  3. Observe Ignition 1 on the scan tool.

Is Ignition 1 voltage between the specified values?

10.0-16.0V

System OK

Go to Step 2