The powertrain control module (PCM) uses the 5-volt reference circuit as a sensor feed to the following sensors:
• | The A/C pressure sensor |
• | The throttle position (TP) sensor 1 |
• | The accelerator pedal position (APP) sensor 2 |
• | The fuel tank pressure (FTP) sensor |
• | The supercharge inlet pressure (SCIP) sensor |
• | The barometric pressure (BARO) sensor |
• | The camshaft position (CMP) sensor |
The PCM monitors the voltage on the 5-volt reference circuit. If the voltage is out of tolerance, the PCM will set DTC P0641.
This diagnostic procedure supports the following DTC:
DTC P0641 5-Volt Reference 1 Circuit
• | DTCs P0601, P0602, P0604, P0606, P1621, and P2610 are not set. |
• | The ignition is in unlock, accessory, run, or crank mode. |
• | The ignition voltage is greater than 5.2 volts. |
• | DTC P0641 runs continuously when the above conditions are met. |
• | The PCM detects a voltage out of tolerance condition on the 5-volt reference circuit. |
• | The above condition is present for 1 second. |
• | The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. |
• | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records. |
• | 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 | ||||||||||
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Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls 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 Intermittent Conditions | ||||||||||
3 | Visually and physically inspect the powertrain control module (PCM) and engine grounds. Ensure that the grounds are clean and secure. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 4 | ||||||||||
4 |
Is the voltage within the specified range? | 4.8-5.2 V | Go to Step 6 | Go to Step 5 | ||||||||||
5 | Is the voltage more than the specified value? | 5.2 V | Go to Step 9 | Go to Step 7 | ||||||||||
6 |
Is the voltage within the specified range? | 4.8-5.2 V | Go to Intermittent Conditions | Go to Step 11 | ||||||||||
7 |
Was a component replaced? | -- | Go to Step 12 | Go to Step 8 | ||||||||||
8 | Test the 5-volt reference 1 circuits for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 10 | ||||||||||
9 |
Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 10 | ||||||||||
10 | Replace the PCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 12 | -- | ||||||||||
11 | Replace the A/C refrigerant pressure sensor. Refer to Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- | ||||||||||
12 |
Did the DTC fail this ignition? | -- | Go to Step 3 | Go to Step 13 | ||||||||||
13 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK |