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Home >> Cadillac >> 2006 >> STS Base, 3.6 7, RWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 13 (Engine Control System - 4.6L (LH2) - DTC P0420 To P0689) >> DTC P0451 >> Conditions for Clearing the MIL/DTC

Conditions for Clearing the MIL/DTC

WARNING: This page is about a different variant/trim than selected.
DTC P0451

Step Action Value(s) Yes No
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Control Module Connector End Views or Engine Controls 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
  1. Idle the engine for 1 minute.
  2. Monitor the DTC information using the scan tool.
Did DTC P0651 fail this ignition?
- Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information Go to Step 3 
3
  1. Turn ON the ignition, with the engine OFF.
  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 in Wiring Systems.
Is the voltage within the specified value?
4.9-5.1 V Go to Step 4  Go to Step 6 
4
  1. Turn OFF the ignition.
  2. Connect a 3-amp fused jumper wire between the 5-volt reference circuit of the FTP sensor and the signal circuit of the FTP sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. Observe the FTP sensor voltage with a scan tool.
Is the Fuel Tank Pressure sensor parameter within the specified value?
4.9-5.1 V Go to Step 5  Go to Step 8 
5 Measure the voltage from the 5-volt reference circuit to the low reference circuit with a DMM.
Is the voltage within the specified value?
4.9-5.1 V Go to Step 9  Go to Step 7 
6 Test the 5-volt reference circuit for an open circuit or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
- Go to Step 13  Go to Step 10 
7 Test the low reference circuit of the FTP sensor for an open or for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
- Go to Step 13  Go to Step 10 
8 Test the signal circuit for the following conditions:
  • High resistance
  • Damage
  • Corrosion

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
- Go to Step 13  Go to Step 10 
9 Test for an intermittent and for a poor connection at the FTP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
- Go to Step 13  Go to Step 11 
10 Test for an intermittent and for a poor connection at the control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
- Go to Step 13  Go to Step 12 
11 Replace the FTP sensor. Refer to Fuel Tank Pressure Sensor Replacement .
Did you complete the replacement?
- Go to Step 13  -
12 Replace the engine control module (ECM). Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.
Did you complete the replacement?
- Go to Step 13  -
13
IMPORTANT: DO NOT exceed the specified value in this step. Exceeding this specified value may produce incorrect test results.
  1. Connect the J 41413-200  Evaporative Emission System Tester (EEST) to the fuel fill pipe.
  2. Turn the nitrogen/smoke valve to NITROGEN.
  3. Seal the EVAP Purge/Seal function with a scan tool.
  4. Pressurize the evaporative emission (EVAP) system to the specified value.
  5. Observe the fuel tank pressure sensor parameter with a scan tool.
Does the fuel tank pressure sensor parameter remain constant?
5 in H2O Go to Step 14  Go to Step 2 
14 Observe the fuel tank pressure sensor parameter with a scan tool.
Is the difference between the scan tool fuel tank pressure sensor parameter and the J 41413-200  gage within the specified value?
1 in H2O Go to Step 15  Go to Step 2 
15
  1. Observe the fuel tank pressure parameter with the engine OFF.
  2. Increase the EVAP purge solenoid valve to 100 percent.
Does the pressure decrease?
- Go to Step 16  Go to Step 2 
16
  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 17 
17 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