For 1990-2009 cars
Engine Controls Components
Cell 20: Engine Data Sensors - TP, ECT, IAT and Fuel Tank
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

The EVAP Purge valve is supplied power via the Engine Controls Power Relay (Switched B+). The Engine Control Module (ECM) controls the valve by grounding the control circuit via an internal solid state device called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line which is monitored by the ECM. When the ECM is commanding a component on, the voltage of the control circuit should be low (near 0 volts). When the ECM is commanding the control circuit to a component off, the voltage potential of the circuit should be high (near battery voltage). If the fault detection circuit senses a voltage other than what is expected, this DTC will set.

The ECM will monitor the EVAP Purge valve circuit for the following:

• | A short to ground

• | A short to voltage

• | An open circuit

• | An open component

• | An internally shorted or excessively low resistance EVAP Purge valve circuit

When the ECM detects any of the above malfunctions, this DTC will set and the affected driver will be disabled. The ECM will continue to test the circuit and if the fault goes away, the driver will be reactivated.

### Conditions for Running the DTC

• | The ignition voltage is between 9.0 and 17.0 volts.

• | The engine speed is greater than 80 RPM.

### Conditions for Setting the DTC

A short to ground, an open circuit, or a short to battery voltage is detected on the control circuit.

### Action Taken When the DTC Sets

• | The ECM illuminates the Malfunction Indicator Lamp (MIL) and records the operating conditions in the Freeze Frame on the second consecutive drive trip that the diagnostic runs and fails.

• | The ECM records the operating conditions in the Freeze Frame on the first drive trip that the diagnostic runs and fails (Fail Pending).

### Conditions for Clearing the MIL/DTC

• | The ECM turns OFF the MIL after three consecutive drive trips that the diagnostic runs and passes.

• | A History DTC clears after forty consecutive warm-up cycles in which no failures are reported by this diagnostic or any other emission related diagnostic.

• | The ECM battery voltage is interrupted.

• | The scan tool clears the MIL/DTC.

### Diagnostic Aids

Use the Connector Test Adapter Kit J35616-A for any test that requires probing the ECM harness connector or a component harness connector. Using this kit will prevent damage to the harness connector terminals.

Check for the following conditions:

• | Poor connections at the ECM or at the component. Inspect the harness connectors for any backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. Refer to Electrical Diagnosis in Engine Electrical, Troubleshooting Procedures, Checking Terminal Contact for proper procedure.

• | Misrouted harness. Inspect the harness in order to ensure that the harness is not routed too close to any high voltage wires such as spark plug leads, or too close to any high current devices such as the alternator, the motors, the solenoids, etc.

• | Damaged harness. Inspect the wiring harness for any damage. If the harness appears to be OK, observe the scan tool while moving the related connectors and the wiring harnesses. A change in the display may help in order to locate the fault.

Refer to Symptoms for the Intermittents.

### Test Description

The number(s) below refer to the step numbers on the diagnostic table.

1. Listen for an audible click when the valve operates. Repeat the commands as necessary.

2. This check can detect a partially shorted coil which would cause excessive current flow. Leaving the circuit energized for 2 minutes allows the coil to warm up. When warm, the coil may open (amps drop to 0), or short (goes above 0.75 amp).

3. If no trouble is found in the control circuit or the connection at the ECM, the ECM may be damaged, however, this is an extremely unlikely failure.

#### DTC P0443 - Evaporative Emission (EVAP) Purge Valve Control

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 |

1. Turn on the ignition with the engine off.
2. Command the valve on and off with the scan tool.

Does the valve turn on and off with each command?

--

Go to Step 3

Go to Step 5

3 |

1. Turn off the ignition.
2. Disconnect the ECM.
3. Jumper the engine controls power relay control circuit to ground.
4. Use the DVM J 39200 on 10 Amp scale in order to measure the current from the valve control circuit in the ECM harness connector to ground for 2 minutes.

Does the current draw a measure within the range shown?

0.1-0.75 A

Refer to Diagnostic Aids

Go to Step 4

4 |

1. Turn off the ignition.
2. Disconnect the purge valve.
3. Measure the resistance from the valve control circuit in the ECM harness connector to ground with the DVM J 39200 .

The DVM should display an infinite resistance.

Does the DVM display an infinite resistance?

--

Go to Step 11

Go to Step 9

5 |

1. Turn off the ignition.
2. Disconnect the purge valve.
3. Connect test light J 34142-B between the terminals in the harness connector.
4. Turn on the ignition.
5. Command the valve on and off with the scan tool.

Does the test light turn on and off with each command?

--

Go to Step 8

Go to Step 6

6 | Probe the Switched B+ circuit in the valve harness connector with the test light connected to ground. The test light should illuminate. Does the test light illuminate? | -- | Go to Step 7 | Go to Step 10
7 |

1. Turn off the ignition.
2. Reconnect the valve.
3. Disconnect the ECM.
4. Jumper the engine controls power relay control circuit to ground.
5. Probe the valve control circuit in the ECM harness connector with a fused jumper wire connected to ground.
6. Turn on the ignition with the engine off.

Does the valve operate?

--

Go to Step 12

Go to Step 9

8 | Check the connections at the valve and the related wiring at the solenoid and the ECM. Was a problem found and corrected? | -- | Go to Step 14 | Go to Step 11
9 | Repair the valve control circuit. Is the action complete? | -- | Go to Step 14 | --
10 | Repair the Switched B+ circuit to the valve. Is the action complete? | -- | Go to Step 14 | --
11 | Replace the valve. Is the action complete? | -- | Go to Step 14 | --
12 | Check for a poor connection or poor terminal tension at the ECM harness connector. Refer to Engine Control Module Diagnosis for the proper procedure. Was a problem found and corrected? | -- | Go to Step 14 | Go to Step 13
13 | Important: This vehicle is equipped with a Theft Deterrent System which interfaces with the Engine Control Module (ECM). Program the new ECM with the frequency code of the theft deterrent module that is currently on the vehicle. Replace the ECM. Refer to Engine Control Module Replacement/Programming .

Is the action complete?

--

Go to Step 14

--

14 |

1. Clear the DTCs with the scan tool.
2. Turn off the ignition for 15 seconds.
3. Operate the vehicle within the conditions that are required for this diagnostic to run. Refer to Conditions for Running the DTC.
4. Check for any DTCs.

Is this DTC set?

--

Go to Step 2

Go to Step 15

15 | Were there any additional DTCs noted during the Powertrain OBD System Check that have not been diagnosed? | -- | Go to the applicable DTC table | The System is OK