Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptors
DTC P0642: 5-Volt Reference 1 Circuit Low VoltageDTC P0643: 5-Volt Reference 1 Circuit High Voltage
Diagnostic Fault Information
Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance |
|---|---|---|---|---|---|
APP Sensor 1 - 5-Volt Reference | P0237, P0340, P0462, P0522, P0642, P2067, P2122, P2454, P2564 | P2138 | P2122 | P0238, P0340, P0401, P0463, P0523, P0643, P2068, P2455, P2565 | -- |
Boost Sensor - 5-Volt Reference | P0237, P0340, P0462, P0522, P0642, P2067, P2122, P2454, P2564 | P0101 | P0237 | P0238, P0340, P0401, P0463, P0523, P0643, P2068, P2455, P2565 | -- |
TC Vane Position Sensor - 5-Volt Reference | P0237, P0340, P0462, P0522, P0642, P2067, P2122, P2454, P2564 | P2563 | P2564 | P0238, P0340, P0401, P0463, P0523, P0643, P2068, P2455, P2565 | -- |
EGR Valve - 5-Volt Reference | P0237, P0340, P0462, P0522, P0642, P2067, P2122, P2454, P2564 | P046C | P0405 | P0238, P0340, P0401, P0463, P0523, P0643, P2068, P2455, P2565 | -- |
Camshaft 4 X - 5-Volt Reference | P0237, P0340, P0462, P0522, P0642, P2067, P2122, P2454, P2564 | P0340 | P0340 | P0238, P0340, P0401, P0463, P0523, P0643, P2068, P2455, P2565 | -- |
Intake Air Flow Valve | P0237, P0340, P0462, P0522, P0642, P2067, P2122, P2454, P2564 | P02E7 | P02E8 | P0238, P0340, P0401, P0463, P0523, P0643, P2068, P2455, P2565 | -- |
Fuel Tank Level Sensor 1 and 2 | P0237, P0340, P0462, P0522, P0642, P2067, P2122, P2454, P2564 | P2068 | P2068 | P0238, P0340, P0401, P0463, P0523, P0643, P2068, P2455, P2565 | -- |
Oil Pressure Sensor - 5-Volt Reference | P0237, P0340, P0462, P0522, P0642, P2067, P2122, P2454, P2564 | P0522 | P0522 | P0238, P0340, P0401, P0463, P0523, P0643, P2068, P2455, P2565 | -- |
Fuel Rail Pressure Sensor 5-Volt Reference | P0237, P0340, P0462, P0522, P0642, P2067, P2122, P2454, P2564 | P0087, P0192 | P0193 | P0238, P0340, P0401, P0463, P0523, P0643, P2068, P2455, P2565 | -- |
DPF Differential Pressure Sensor | P0237, P0340, P0462, P0522, P0642, P2067, P2122, P2454, P2564 | P2453, P244B | P2454 | P0238, P0340, P0401, P0463, P0523, P0643, P2068, P2455, P2565 | -- |
PTO Accelerator Position Sensor 5-Volt Reference | -- | -- | -- | -- | -- |
Circuit/System Description
The engine control module (ECM) supplies 5 volts to components through 5-volt reference circuits. These 5-volt reference circuits are independent of each other outside the ECM, but are bussed together in three reference groups inside the ECM. Therefore, a circuit condition on one sensor 5-volt reference circuit may affect multiple components. The ECM monitors voltage on the 5-volt reference circuits.
Conditions for Running the DTC
P0642
| • | DTC P0643 is not set. |
| • | The ignition is ON for more than 2 seconds. |
| • | The battery voltage is between 10-16 volts. |
P0643
| • | DTC P0642 is not set. |
| • | The ignition is ON for more than 2 seconds. |
| • | The battery voltage is between 10-16 volts. |
Conditions for Setting the DTC
P0642
The ECM detects the 5-volt reference 1 circuit voltage is less than 4.5 volts.
P0643
The ECM detects the 5-volt reference 1 circuit voltage is more than 5.5 volts.
Action Taken When the DTC Sets
DTC P0642 and P0643 are Type A DTCs.
Conditions for Clearing the MIL/DTC
DTC P0642 and P0643 are Type A DTCs.
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
Scan Tool Reference
Circuit/System Verification
- The engine starts and runs.
- Observe the 5-Volt Reference 1 Circuit Status parameter with a scan tool. The parameter should display OK.
- Engine running, observe the DTC information with a scan tool. DTCs P0642 or P0643 should not set.
- 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 data.
Circuit/System Testing
- Turn OFF the ignition for 30 seconds or until the ECM powers down.
- Disconnect the camshaft position (CMP) sensor.
- Turn ON the ignition, with engine OFF and measure the voltage from the 5-volt reference circuit of the CMP sensor to a good ground with a DMM.
- With the DMM still connected to the 5-volt reference circuit, disconnect all other components connected to the 5-volt reference 1, one at a time. Refer to Diagnostic Fault Information.
- Test the 5-volt reference 1 circuits for a short to ground or a short to voltage.
| ⇒ | If the voltage measures 4.7-5.2 volts, replace the camshaft position sensor. |
| ⇒ | If voltage changes when one of the above components is disconnected, replace the component. Refer to the appropriate replacement procedure. |
| ⇒ | If no problem was found in the 5-volt reference circuit, replace the ECM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |
