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 |
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 | |||||
2 |
Did the DTC fail this ignition? | -- | Go to Step 3 | Go to Testing for Intermittent Conditions and Poor Connections | ||||
3 |
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 |
Is the voltage within the specified range? | 4.8-5.2 V | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 9 | ||||
6 |
Was the component replaced? | -- | Go to Step 11 | Go to Step 7 | ||||
7 | Test the 5-volt reference circuit 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 11 | Go to Step 10 | ||||
8 | Test all the 5-volt reference circuits and 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 11 | Go to Step 10 | ||||
9 | Replace the TP sensor. Refer to Throttle Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 11 | -- | ||||
10 | Replace the powertrain control module (PCM). Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 11 | -- | ||||
11 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 12 | ||||
12 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |||||
