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Home >> Cadillac >> 2006 >> STS Base, 3.6 7, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - 3.6L - DTC P0342 To P0690 >> DTC P0459 >> Test Description
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Test Description

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

  1. 2:  This step determines if a condition exists. The EVAP canister purge valve is PWM. An audible click should be heard when the purge valve is commanded to 50 percent and should stop when the EVAP canister purge valve is commanded to 0 percent. The rate at which the valve cycles should increase as the commanded state is increased and decreased as the commanded state is decreased. Repeat the commands as necessary.
DTC P0459 Evaporative Emission (EVAP) Purge Solenoid Control Circuit High Voltage

Step Action 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
2 
  1. Start the engine.
  2. Observe the DTC Info with a scan tool.
Does the DTC fail this ignition?		 Go to Step 4  Go to Step 3 
3
  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.
Did the DTC fail this ignition?		 Go to Step 4  Go to Diagnostic Aids
4
  1. Turn OFF the ignition.
  2. Disconnect the evaporative emission (EVAP) canister purge valve harness connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp between the control circuit of the EVAP canister purge valve to the engine control module (ECM) housing.
Does the test lamp illuminate?		 Go to Step 5  Go to Step 6 
5
IMPORTANT: The control circuit for the solenoid is pulled-up to voltage within the ECM, 2.6-4.6 volts on the control circuit is normal.
Test the control circuit of the EVAP canister purge valve for a short to voltage. Refer to Circuit Testing and Wiring Repairs .Did you find and correct the condition?		 Go to Step 10  Go to Step 7 
6 Test for shorted terminals and for poor connections at the EVAP canister purge valve. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 Go to Step 10  Go to Step 8 
7 Test for shorted terminals and for poor connections at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 Go to Step 10  Go to Step 9 
8 Replace the EVAP canister purge valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement .
Did you complete the replacement?		 Go to Step 10  -
9 Replace the ECM. Refer to Control Module References for replacement, setup, and programming.
Did you complete the replacement?		 Go to Step 10  -
10
  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 11 
11 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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