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Models With Fault Indicator Lamp

Typical Fault Indicator Light:






Audi vehicles with the CIS-EIII engine control system, which are also equipped with a fault indicator lamp, have a permanent fault memory. Any emission related trouble codes that set will remain in the computer memory until manually erased. Other non-emission related codes are stored in a volatile memory and cleared each time the engine is started, or in some cases, when the ignition is turned "off". The ignition and fuel control units each have their own fault memory. The fault lamp will illuminate when a problem is detected by either ECU. If the problem is intermittent, the light may go out when the fault is no longer present, or may stay on until the memories are cleared (depending on the particular software in the computer).


Fault Memory Display Test Connector:






NOTE: Not all systems with the fault lamp will display codes through the lamp. Some require connecting an LED test light between a special test lead (located near the fuel distributor) and the battery positive terminal (or other battery power source) to display codes. On these systems, the LED will flash codes in the same manner as other systems that use the fault lamp for display. To find out which system you are attempting to test, activate fault memory display (see procedure below) and observe fault lamp. If fault lamp does not flash a code, then it will be necessary to connect an LED test light to display codes. In this case the fault lamp is used only to inform the operator that a fault has been detected and a trouble code has been stored.


ACTIVATING FAULT MEMORY DISPLAY


Under Dash Diagnostic Connectors:






Beginning in 1989, some Audi models will have new test connectors for activating and reading fault codes. These new connectors are color coded for identification and are located below the dash panel, on the driver's side. Vehicles equipped with these connectors do not display through the fault indicator lamp. Instead, an LED test light must be connected between the test connectors to display codes. Models with these new connectors may still use a fuel pump relay with a fuse receptacle on top. Inserting a fuse into the relay will cause the fault indicator lamp to illuminate and stay on until the fuse is removed, however, this is a fuse check only. The fault memory display cannot be activated through the fuel pump relay.
On models not equipped with the new style diagnostic test connectors, the fault memory display is activated in the same manner as earlier models, by inserting a fuse into the top of the fuel pump relay for four seconds and then removing. When activated, codes will display by the flashing of either the fault lamp or a properly connected LED test light.

VEHICLES WITHOUT UNDER DASH TEST CONNECTORS use the following procedure to display fault codes.

1. Make sure all fuses are OK, and operate vehicle for at least 5 minutes, being sure that engine speed excedes 3,000 rpm at least once and throttle is opened to wide open throttle position at least once ("punch it" once during test drive), then let engine idle for an additional 2 minutes. Do not turn engine off as some models will erase the temporary fault memory when the ignition is turned off.

a. If the engine won't start, make sure all fuses are OK, and use the ignition key in the start position to crank it over for at least 6 seconds. This will allow the control units to read signals from input sensor, check for incorrect readings, and restore or set fault codes (if any). Don't turn ignition off, fault memory may be erased.


Fault Memory Display Test Connector:




Schematic Representation Of Fault Lamp And Fuel Pump Relay Connectionsrctions:




Schematic Representation Of Test Light And Fuel Pump Relay Connections:






2. With engine running (or key "on"), connect LED test light negative lead to test connector near fuel distributor, and positive lead to battery positive terminal (if vehicle is not one that displays via fault lamp). If you are not sure which lead on your test light is the positive lead, connect test light between the battery terminals. If the LED lights up, you have the positive lead on the positive terminal. If not, reverse the connections. If it still doesn't light, get a new test light.


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






3. Insert a good fuse into the receptacle on top of the fuel pump relay for at least 4 seconds, then remove. Fault memory display is now activated.

4. Observe fault indicator lamp (or LED). A start up code will display (light on once for 2.5 seconds then off for 2.5 seconds) followed by the first code stored in memory.

5. After the first code is displayed and recorded, insert fuse into the relay again for 4 seconds, then remove, to retrieve the next code. This step must be repeated for each code until ending code 0000 is displayed, indicating all stored codes have been displayed. Code 0000 is represented by the light coming on for 2.5 seconds at regular 2.5 second intervals. Record all codes as they are displayed.

6. Turn ignition "off", and remove test light.

VEHICLES WITH UNDER DASH TEST CONNECTORS

1. Same as step #1 above.


Diagnostic Connectors - Activating Self Diagnostics:






2. With engine running (or key "on"), connect LED test light positive lead to top terminal of black connector, and negative lead to bottom terminal of brown connector, using appropriate flat male connectors. Also, connect one end of a jumper wire to the bottom terminal of the black connector, and leave the other end free.

3. Touch the free end of the jumper wire to the bottom terminal of the brown connector for at least 4 seconds, then remove. Fault memory is now activated.

4. Observe LED. A start up code will display (light on once for 2.5 seconds then off for 2.5 seconds) followed by the first code stored in memory.

5. After the first code is displayed and recorded, touch the free end of the jumper wire to the bottom terminal of the brown connector again for 4 seconds then remove, to retrieve the next code. This step must be repeated for each code until ending code 0000 is displayed, indicating all stored codes have been displayed. Code 0000 is represented by the light coming on for 2.5 seconds at regular 2.5 second intervals. Record all codes as they are displayed.

6. Turn ignition "off". Remove jumper wire and test light.

READING FAULT CODES

When the fault memory display is activated, the fault lamp (or LED) will display a start signal, and then the first code, by flashing the fault lamp (or the properly connected LED test light). Codes are four digits long and are read by counting the number of flashes in each sequence.


Reading Fault Codes:






After one sequence of flashes is displayed, designating one code, that sequence will repeat until the next sequence is manually activated. For example, 2 flashes-short pause, then 1 flash-short pause, then 2 flashes-short pause, then 3 flash-long pause, repeat, indicates a code 2123 (full throttle switch - shorted switch or grounded wire). The next code will not display until activated in the same way as the first. The ignition ECU will display it's memory first. When all ignition related codes have been displayed, the fuel control unit will begin displaying it's codes. All codes are read in the same manner except for code 0000 (end of display) which is displayed by the light staying on for 2.5 seconds, then going out for 2.5 seconds alternately.
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