| • | 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. | 
Circuit  | Short to Ground  | High Resistance  | Open  | Short to Voltage  | Signal Performance  | 
|---|---|---|---|---|---|
CKP Sensor 5-Volt Reference  | P0652, P0335, P2127  | P0335  | P0335  | P0335, P0653, P2128  | --  | 
APP Sensor 2 - 5-Volt Reference  | P0335, P0652, P2127  | P2138  | P2127  | P0653, P2128  | --  | 
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.
| • | DTC P0653 is not set. | 
| • | The ignition is ON for more than 2 seconds . | 
| • | The battery voltage is between 10-16 volts. | 
| • | DTC P0652 is not set. | 
| • | The ignition is ON for more than 2 seconds . | 
| • | The battery voltage is between 10-16 volts. | 
The ECM detects the 5-volt reference 2 circuit voltage is less than 4.5 volts.
The ECM detects the 5-volt reference 2 circuit voltage is more than 5.5 volts.
DTC P0652 and P0653 are Type A DTCs.
DTC P0652 and P0653 are Type A DTCs.
Control Module References for scan tool information
| • | The engine starts and runs. | 
| • | Observe the 5-Volt Reference 2 Circuit Status parameter with a scan tool. The parameter should display OK. | 
| ⇒ | If the voltage measures 4.7-5.2 volts, replace the APP 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 2 circuit , replace the ECM. | 
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |