Scan Tool Testing and Procedures

The CIS-EIII engine control system has a self diagnostic mode where it actually operates specific output devices in sequence. This allows technicians to check (audibly or with DVM) whether or not certain devices and circuits are working. This "output check" mode is initiated in similar manner as the fault memory display, except that you start with the ignition turned "off". There are four separate output checks generated in a specific order, each with its own identifying code and separated by an activation step which the technician must manually perform. Once the first output check is initiated, each time the fuse is inserted into the fuel pump relay (or jumper wire connected between test connectors), the next output check will be initiated. In this way, if you only wanted to test the idle stabilizer (3rd output check), you can simply step through the other tests.

Output checks will occur in the following order:

1. Code 4341
Differential pressure regulator current check (tests the ability of the fuel control unit to vary the output current to the pressure actuator by deliberately creating two different output signals so the technician can check for the correct response).

2. Code 4343
Carbon canister shut-off solenoid check (tests solenoid and wiring by deliberately creating an output signal to the solenoid so the technician can monitor it for a response).

3. Code 4431
Idle stabilizer valve check (checks for correct operation of idle stabilizer valve when a signal is applied).

4. Code 4443
Cold start valve check (checks for correct operation of cold start valve when a known signal is applied).

5. Code 0000
End of output checks


ACTIVATING OUTPUT CHECKS
After having displayed and recorded all fault codes, use the following procedure to perform output checks.

Harness Adapter For Checking Differential Pressure Regulator Current:

1. Disconnect electrical connector from differential pressure regulator and install appropriate Audi electrical harness adapter (part #VW 1315 A/1 or 1315 A/Z, depending on application).

Checking Differential Pressure Regulator Current:

2. Connect DVM to adapter, set mode to DC milliamps 200mA scale.

Fuse/Relay Panel Showing Fuel Pump Relay w/Fuse Receptacle:

Diagnostic Connectors - Activating Self Diagnostics:

3. With ignition "off" insert fuse into top of fuel pump relay (or jumper test connectors under dash), then turn ignition "on" but do not start engine. Wait at least 4 seconds then remove fuse from relay (or disconnect jumper wire from brown connector). The first output check is now activated. A code 4341 should be displayed. In this mode, the codes are output codes and indicate which device or circuit is being tested.

^ DVM should display approximately 100 mA current to differential pressure regulator. If there is no reading, check wiring between fuel control unit and pressure regulator connector.

Full Throttle Switch:

4. Manually close the full throttle switch, and watch the voltmeter.

^ Current to regulator should drop to approximately 10mA with full throttle switch closed. If there is no change, check throttle switches, wiring and connections, repair if necessary and try again. If wiring and throttle switches are OK and actuator current still does not change in as described in this step, then the fuel control unit is faulty.

5. Switch to the next step by re-inserting fuse into relay (or reconnecting jumper wire) for 4 seconds, then remove. The next output check is now activated.

^ Code 4343 should be displayed (carbon canister shut-off solenoid check).

6. Close the full throttle switch again.

^ An audible "clicking" should be heard from the canister shut-off solenoid while the full throttle switch is closed, indicating that the solenoid and circuit are OK.

7. Switch to next step (repeat step 5).

^ Code 4431 should be displayed (idle stabilizer valve check).

8. Close the full throttle switch again.

^ An audible "clicking" should be heard from the idle stabilizer valve (it may be difficult to hear the clicking, in which case an LED test light may be connected to the harness in place of the idle stabilizer valve and the output check done again. Look for the LED to flash when output code 4431 is obtained and full throttle switch closed).

9. Switch to next step (repeat step 5 again!?!).

^ Code 4443 should be displayed.

10. Close the full throttle switch again.

^ The cold start valve should click on and off, for a maximum of 10 seconds.

NOTE: If the correct outputs are not obtained, check wiring and connections, repair as necessary.

If either control unit will not enter output check mode, check continuity of wires between diagnostic connectors and control unit. Also check for power at top terminal of black diagnostic connector (should have battery power), and check control units and wire at bottom terminal of black diagnostic connector for good ground connections. Repair as necessary. If no wiring or power supply problems are found, and control units still won't enter output check mode, then one or both control units are faulty.