GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The powertrain control module (PCM) provides a 5-volt supply for use in powering up the sensors. This test monitors the voltage present at terminals BRD13, shared by boost and crankshaft position (CKP) sensors, and BRD14, the optical/fuel temperature sensor (Cam/HI. Res).

Conditions for Running the DTC

The ignition is in the ON position.

Conditions for Setting the DTC

The 5-volt reference is less than 1 volt.

Action Taken When the DTC Sets

    • The control module stores the DTC information into memory when the diagnostic runs and fails.
    • The malfunction indicator lamp (MIL) will not illuminate.
    • The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
    • The driver information center, if equipped, may display a message.

Conditions for Clearing the DTC

    • A current DTC Last Test Failed clears when the diagnostic runs and passes.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
    • Clear the DTC with a scan tool.

Diagnostic Aids

During the time the failure is present, the setting of additional DTCs that share a 5-volt reference may also set.

Test Description

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

  1. This step confirms whether a DTC is still present.

  2. This step determines if there is a 5-volt reference from the PCM.

  3. This step determines if there is a short to ground in the reference circuit or a short-to-ground in the PCM.

  4. This step determines if the short is being caused by one of the sensors or the short is in the wiring harness.

Step

Action

Yes

No

Schematic Reference: Engine Controls Schematics

1

Important: Before clearing the DTCs, use the scan tool Capture Info to save the Freeze Frame/Failure Records for reference. The data in the control module is deleted once the Clear Info function is used.

Did you perform the Diagnostic System Check-Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

  1. Install the scan tool.
  2. Crank the engine for 15 seconds, or start the engine.

Does the DTC set?

Go to Step 3

Go to Step 5

3

  1. Turn ON the ignition, with the engine OFF.
  2. Disconnect the boost sensor.
  3. Use a DMM in order to probe the 5-volt reference circuit at the harness connector.

Does the voltage measure less than the specified value?

Go to Step 4

Go to Step 6

4

  1. Disconnect the PCM connector with the boost sensor 5-volt reference circuit.
  2. With an Unpowered Test Light connected to B+, probe the 5-volt reference circuit at the PCM harness.

Does the test lamp illuminate?

Go to Step 7

Go to Step 8

5

The DTC is intermittent. If no additional DTCs are stored, refer to the Diagnostic Aids. If any additional DTCs are stored, refer to those tables.

Are there any additional DTCs stored?

Go to Diagnostic Trouble Code (DTC) List

Go to Diagnostic Aids

6

Replace the boost sensor. Refer to Boost Sensor Replacement .

Did you complete the replacement?

Go to Step 12

--

7

With the J 35616-200 Unpowered Test Lamp still probing the boost sensor 5-volt reference circuit at the PCM, disconnect each sensor, one at a time, that shares the 5-volt reference with the boost sensor.

Does the J 35616-200 turn OFF when one of the sensors is disconnected?

Go to Step 9

Go to Step 10

8

  1. Disconnect the PCM connector with the fuel temperature sensor 5-volt reference circuit.
  2. With a J 35616-200 connected to B+, probe the fuel temperature 5-volt reference circuit at the PCM harness.

Does the test lamp illuminate?

Go to Step 10

Go to Step 11

9

Replace the sensor that caused the J 35616-200 to turn OFF.

Did you complete the replacement?

Go to Step 12

--

10

Repair a short to ground in a 5-volt reference circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 12

--

11

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

Go to Step 12

--

12

  1. Use the scan tool in order to clear the DTCs.
  2. Start the engine.
  3. Allow the engine to idle until the engine reaches the normal operating temperature.
  4. Select DTC and the Specific DTC function.
  5. Enter the DTC number that was set.
  6. Operate the vehicle within the Conditions for Setting this DTC until the scan tool indicates the diagnostic Ran.

Does the scan tool indicate the diagnostic passed?

Go to Step 13

Go to Step 2

13

Does the scan tool display any additional undiagnosed DTCs?

Go to Diagnostic Trouble Code (DTC) List

System OK