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Home >> Cadillac >> 2006 >> Escalade EXT >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - 4.8L, 5.3L, And 6.0L - DTC P0442 To DTC P2120 >> DTC P0651 >> Test Description

Test Description

The number below refers to the step number on the diagnostic table.

  1. 9:  A short to voltage on the signal circuit of the FTP sensor will backfeed through the sensor into the 5-volt reference circuit and set this DTC.
DTC P0651

Step Action Values Yes No
Schematic Reference:  Engine Controls Schematics 
Connector End View Reference: Engine Controls Component Views or 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
2
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. 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?		 - Go to Step 3  Go to Testing for Intermittent Conditions and Poor Connections
3
  1. Turn OFF the ignition.
  2. Disconnect the air conditioning (A/C) pressure sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the 5-volt reference circuit of the A/C pressure sensor to a good ground with a DMM. Refer to Circuit Testing .
Is the voltage within the specified range?		 4.8-5.2 V Go to Step 4  Go to Step 5 
4
  1. Connect the A/C pressure sensor.
  2. Disconnect the fuel tank pressure (FTP) sensor.
  3. Measure the voltage from the 5-volt reference circuit of the FTP sensor to a good ground with a DMM. Refer to Circuit Testing .
Is the voltage within the specified range?		 4.8-5.2 V Go to Testing for Intermittent Conditions and Poor Connections Go to Step 11 
5 Is the voltage measured in step 3 more than the specified value? 5.2 V Go to Step 8  Go to Step 6 
6 Monitor the DMM while disconnecting the FTP sensor.
Does the voltage return to within the specified range when the FTP is disconnected?		 4.8-5.2 V Go to Step 10  Go to Step 7 
7
  1. Turn OFF the ignition.
  2. Disconnect the powertrain control module (PCM).
  3. Test the 5-volt reference circuit for a short to ground or any sensor low reference circuit. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 13  Go to Step 12 
8 Test all 5-volt reference circuits for a short to voltage. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 13  Go to Step 9 
9  Test the FTP sensor signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 13  Go to Step 12 
10 Replace the FTP sensor. Refer to Fuel Tank Pressure Sensor Replacement (1500 Series) or Fuel Tank Pressure Sensor Replacement (2500 Series) .
Did you complete the replacement?		 - Go to Step 13  -
11 Replace the A/C pressure sensor. Refer to Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement .
Did you complete the replacement?		 - Go to Step 13  -
12 Replace the PCM. Refer to Control Module References for replacement, setup, and programming.
Did you complete the replacement?		 - Go to Step 13  -
13
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. 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 14 
14 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 System OK
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