2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2212

2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2212

DTC P0641 or P0651 (ECM)

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System

Check - Vehicle) prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an

overview of the diagnostic approach.

* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure

Instructions)provide an overview of each diagnostic category.

DTC Descriptors

DTC P0641

- 5 V Reference 1 Circuit

DTC P0651

- 5 V Reference 2 Circuit

Circuit/System Description

The engine control module (ECM) has 2 internal 5 V reference busses called 5 V reference 1 and 5 V reference 2. Each reference bus provides 5 V

reference circuits for more than one sensor. Therefore, a fault condition on one 5 V reference circuit will affect the other 5 V reference circuits

connected to that reference bus. The ECM monitors the voltage on the 5 V reference busses.

Conditions for Running the DTC

* The ignition is in Unlock, Accessory, Run, or Crank.

* The ignition voltage is more than 5.23 V.

* DTCs P0641 and P0651 run continuously when the above conditions are met.

Conditions for Setting the DTC

The ECM detects a voltage out of tolerance condition on the 5 V reference 1 or 2 bus for more than 0.5 s.

Action Taken When the DTC Sets

DTCs P0641 and P0651 are Type A DTCs.

Conditions for Clearing the MIL/DTC

DTCs P0641 and P0651 are Type A DTCs.

Diagnostic Aids

The 5 V reference 1 bus provides 5 V to the following sensors:

* B74 manifold absolute pressure (MAP) sensor

* B150 fuel tank pressure (FTP) sensor

* B107 accelerator pedal position (APP) sensor 2

* B1 air conditioning (A/C) refrigerant pressure sensor

* B37B engine oil pressure (EOP) sensor

* B23 camshaft position sensor

The 5 V reference 2 bus provides 5 V to the following sensors:

* B107 APP sensor 1

* Q38 throttle position sensor 1 and 2

* B26 crankshaft position sensor

It may be possible to locate the fault by disconnecting one component at a time from the 5 V reference circuit while viewing the 5 V Reference

Circuit parameter on the scan tool. The scan tool parameter would change fro Fault to OK when the source of the fault is disconnected.

If all 5 V reference components have been disconnected and a Fault is still indicated, the fault may exist in the wiring harness.

Reference Information

Schematic Reference

Engine Controls Schematics (See: Diagrams/Electrical Diagrams/Powertrain Management/System Diagram)