GM Service Manual Online
For 1990-2009 cars only

Object Number: 72708  Size: LF
Automatic Transmission Components
Automatic Transmission Controls Schematics
OBD II Symbol Description Notice

Circuit Description

This DTC will set if an intermittent loss of power to the TCM occurs.

Conditions for Running the DTC

Power on

Conditions for Setting the DTC

An intermittent loss of power to the TCM.

Action Taken When the DTC Sets

    • The MIL/STL will not illuminate.
    • The TCM memory stores the DTC at the time of the first failure.

Conditions for Clearing the MIL/DTC

    • A History DTC clears after forty consecutive warm-up cycles if no failures are present by this or any other non-emission related diagnostic.
    • The scan tool clears the MIL/DTC.

Diagnostic Aids

There may be no problem. If the power was interrupted for any reason, this DTC will set. Has the vehicles battery gone dead or required service recently? Has any other work been done that may have interrupted the power to the TCM? If no trouble is found, the TCM may be the cause of the problem; however, this would be an extremely unlikely failure.

For any test that requires probing the TCM harness connector or a component harness connector, use the Connector Test Adapter Kit J 35616 . Using this kit will prevent damage to the harness connector terminals.

Check for the following conditions:

    • Poor connections at the TCM or at the component. Inspect the harness connectors for any backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. Refer to Engine Electrical, Troubleshooting Procedures, Checking Terminal Contact for proper procedure.
    • Damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, observe the scan tool while moving the related connectors and the wiring harnesses. A change in the display may help to locate the fault.

DTC P1560 - TCM Supply Voltage Interrupted

Step

Action

Value(s)

Yes

No

1

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

Check the power circuits for the following:

    • Inspect the harness connectors for any backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. Refer to Engine Electrical, Troubleshooting Procedures, Checking Terminal Contact for proper procedure.
    • Check the terminals for corrosion.
    • Loose or corroded grounds at the chassis/engine block
    • Fuses in the power supply circuits for loose or dirty connections
    • Open circuit 828.

Was a problem found?

--

Go to Step 3

Go to Diagnostic Aids

3

  1. Clear the scan tool.
  2. Turn off the ignition for 15 seconds.
  3. Start the engine.
  4. Operate the vehicle within the conditions required for this diagnostic to run. Refer to Conditions for Running the DTC.
  5. Check for any DTCs.

Is DTC P1560 set?

--

Go to Step 2

Go to Step 4

4

Were there any additional DTCs noted during the Powertrain or Transmission OBD System Check that have not been diagnosed?

--

Go to the applicable DTC table

Go to Step 5

5

Does the Transmission now function properly?

--

System OK

Go to Functional Test