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For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2006 🢒 Savana - AWD 🢒 Engine 🢒 Engine Controls - 4.8L, 5.3L, and 6.0L 🢒 DTC P0641

Circuit Description

The powertrain control module (PCM) provides 5 volts to the following sensors:

    • The manifold absolute pressure (MAP) sensor
    • The engine oil pressure (EOP) sensor
    • The throttle position (TP) sensor(without TAC)

These 5-volt reference circuits are independent of each other outside the PCM, but are bussed together inside the PCM. Therefore a circuit condition on one sensor 5-volt reference circuit may affect the other sensor 5-volt reference circuits. The PCM monitors the voltage on the 5-volt reference circuit. If the PCM detects the voltage is out of tolerance, DTC P0641 sets.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0641 5-Volt Reference 1 Circuit

Conditions for Running the DTC
    • The engine is running.
    • DTC P0641 runs continuously when the above condition is met.

Conditions for Setting the DTC

The PCM detects a voltage out of tolerance condition on the 5-volt reference circuit for more than 2 seconds.

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

Conditions for Clearing the MIL/DTC
    • The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
    • 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 emission related diagnostic.
    • Clear the MIL and the DTC with a scan tool.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 3

Go to Testing for Intermittent Conditions and Poor Connections

3
  1. Turn OFF the ignition.
  2. Disconnect the engine oil pressure sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the 5-volt reference circuit of the EOP sensor to a good ground with a DMM. Refer to Circuit Testing .

Is the voltage within the specified range?

4.8-5.2 V

Go to Step 5

Go to Step 4

4

Is the voltage more than the specified value?

5.2 V

Go to Step 8

Go to Step 6

5
  1. Connect the EOP sensor.
  2. Disconnect the manifold absolute pressure (MAP) sensor.
  3. Measure the voltage from the 5-volt reference circuit of the MAP sensor to a good ground with a DMM. Refer to Circuit Testing .

Is the voltage within the specified range?

4.8-5.2 V

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 10

6
  1. Monitor the DMM while disconnecting all other devices connected to the 5-volt reference circuit, one at a time. Refer to Engine Controls Component Views .
  2. If the voltage changes when one of the devices are disconnected, replace the component. Refer to appropriate replacement procedure below:
    3. • The MAP sensor--Refer to Manifold Absolute Pressure Sensor Replacement .
    • The engine oil pressure (EOP) sensor--Refer to Engine Oil Pressure Sensor and/or Switch Replacement .
    • The throttle position (TP) sensor--Refer to Throttle Position Sensor Replacement .

Was a component replaced?

--

Go to Step 12

Go to Step 7

7

Test all of the 5-volt reference circuits for a short to ground or any sensor low reference circuit. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 12

Go to Step 11

8

Test all of the 5-volt reference circuits. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 12

Go to Step 9

9

Test the MAP sensor signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 12

Go to Step 11

10

Replace the engine oil pressure (EOP) sensor--Refer to Engine Oil Pressure Sensor and/or Switch Replacement .

Did you complete the replacement?

--

Go to Step 12

--

11

Replace the powertrain control module (PCM). Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 12

--

12
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 2

Go to Step 13

13

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List - Vehicle

System OK