98 EVAP Canister Purge Valve - Short to B+/Short to Ground

P0445

98 EVAP Canister Purge Valve - Short to B+/Short to Ground

Function
The fuel vapors from the fuel tank must not escape into the open air. For this reason, the ventilation line of the fuel tank is routed to an evaporative emission filter (or EVAP canister) that retains the fuel vapors. When driving, air is drawn in through the EVAP canister and picks up the accumulated fuel vapors and feeds them to the combustion process.

The EVAP canister purge valve is installed in the line between the EVAP canister and the intake system. The direction of flow through the valve is indicated by an arrow on the plastic housing.
The output stage that controls the EVAP canister purge valve is monitored.

Diagnosis conditions
- Engine running
- Battery voltage greater than 7 V

P0444 - P0445:

Wiring Diagram







Diagnosis Procedure










1 Check voltage supply for EVAP canister purge valve.
1. Remove connector of EVAP canister purge valve.
2. Connect voltmeter (positive) to EVAP canister purge valve connector, pin 1, and ground.
3. Switch on the ignition.

Display: battery voltage

2 Check EVAP canister purge valve.
1. Remove connector of EVAP canister purge valve.
2. Connect ohmmeter to EVAP canister purge valve, pins 1 and 2.

Display: 26 ± 4 ohms at 20 °C.

3 Check triggering wire for EVAP canister purge valve.
1. Remove connector of EVAP canister purge valve.
2. Connect special tool 9637 to wiring harness (DME control module connector).
3. Connect ohmmeter to EVAP canister purge valve, pin 2, and special tool 9637, pin III/3.

Display: 0 - 5 ohms

4 Perform adaptation.
1. Switch on the ignition.
2. Wait one minute. Do not press the accelerator.
3. Switch off the ignition for at least 10 seconds.
4. Read out the fault memory.

5 Check triggering wire for EVAP canister purge valve for short circuit to B+.
1. Remove connector of EVAP canister purge valve.
2. Connect special tool 9637 to wiring harness (DME control module connector).
3. Connect voltmeter (positive) to EVAP canister purge valve connector, pin 2, and ground.
4. Switch on the ignition.

Display: 0 V

If battery voltage is displayed, check wiring harness for chafing and pinching damage.

6 Check triggering wire for EVAP canister purge valve for short circuit to ground.
1. Remove connector of EVAP canister purge valve.
2. Connect special tool 9637 to wiring harness (DME control module connector).
3. Connect ohmmeter to EVAP canister purge valve connector, pin 2, and ground.

Display: infinity ohms

If 0 to 5 ohms is displayed, check wiring harness for chafing and pinching damage.