Diagnostic Aids

WARNING: This page is about a different car, the 2005 Buick LaCrosse and 2005 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.

If any sensor using a 5-volt bias voltage, such as the intake air temperature (IAT) sensor or fuel sensor, is shorted to voltage, DTC P0651 may set in addition to DTC P0641.
For an intermittent condition, refer to Intermittent Conditions .

DTC P0651

Step	Action	Values	Yes	No
Schematic Reference: Instrument Cluster Schematics in Instrument Panel, Gages, and Console or Engine Controls Schematics Connector End View Reference: Instrument Panel, Gages, and Console Component Views , Instrument Panel, Gages, and Console Connector End Views in Instrument Panel, Gages, and Console or Engine Controls Connector End Views , Powertrain Control Module (PCM) Connector End Views
1	Did you perform the Diagnostic System Check - Vehicle?	-	Go to Step 2	Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2	Observe the Freeze Frame/Failure Records for this DTC. Turn OFF the ignition for 30 seconds. Start the engine. 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. Does the DTC fail this ignition cycle?	-	Go to Step 3	Go to Diagnostic Aids
3	Turn OFF the ignition. Disconnect a sensor associated with the 5 volt reference. Turn ON the ignition, with the engine OFF. Measure the voltage from the 5-volt reference circuit to ground with a DMM. Refer to Circuit Testing in Wiring Systems. Is the voltage within the specified range?	4.8-5.2 V	Go to Intermittent Conditions	Go to Step 4
4	Is the voltage measured in the previous step more than the specified value?	5.2 V	Go to Step 7	Go to Step 5
5	Monitor the DMM while disconnecting all other devices connected to the 5-volt reference circuit, one at a time. Refer to Engine Controls Component Views . If the voltage changes when one of the devices are disconnected, replace the component. Was a component replaced?	4.8-5.2 V	Go to Step 11	Go to Step 6
6	Turn OFF the ignition. Test this 5-volt reference circuit for a short to ground or any sensor low reference circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 11	Go to Step 10
7	Monitor the DMM while disconnecting the BARO sensor (L32) or the Fuel Level Sensor (L26). Does the voltage return to within the specified range when the sensor is disconnected?	4.8-5.2 V	Go to Step 8	Go to Step 9
8	Test the signal circuit of the sensor disconnected in the previous step for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 11	Go to Step 9
9	Test all 5-volt reference circuits for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 11	Go to Step 10
10	Replace the powertrain control module (PCM). Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement?	-	Go to Step 11	-
11	Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. 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. 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?	-	Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information	System OK