The Assembly Line Diagnostic Link Connector

 Click to view an ALDL Connector Diagram

To access ECM error codes: Have the engine ignition key off. For '90 - '93 cars, connect pin A to B. For '94 - '95 cars, connect pin 4 to 6. A paper clip works well as a jumper wire. Turn the ignition key on but don't start the engine. The Service Engine Soon lamp will flash with the code number. Count the blinks. The first code is always a 12. This confirms that the diagnostic system is working. Count one blink with a short delay and then two blinks for a 12. The 12 code will flash three times. The next code is the first error code. It will also flash three times. Record all of the codes until the 12 is flashed again. That means that all of the codes have been flashed and that the system has looped to the beginning of the list. The codes will be displayed in numerical order, not in order of occurrence. To clear the stored codes disconnect the negative battery cable for 10 seconds.

To access CCM error codes: Have the engine ignition key off. For '90 - '93 cars, connect pin A to G. For '94 - '95 cars connect pin 4 to 12. A paper clip works well as a jumper wire. Turn the ignition key on but don't start the engine. The codes will be displayed on the speedometer display. Refer to the service manual section 8D for extensive decoding and diagnostic information. The CCM is mode 1. The ECM is mode 4. Mode 4 normally displays ERR on '93 - '95 ZR-1's.

To access FX3 Selective Ride shock absorber error codes: Have the engine ignition key off. For '90 - '93 cars, connect pin A to C. For '94 - '95 cars connect pin 3 to 4. A paper clip works well as a jumper wire. Turn the ignition key on but don't start the engine. The Service Ride Control lamp will flash the code number. Count the blinks. The first code is always a 12. This confirms that the diagnostic system is working. Count one blink with a short delay and then two blinks for a 12. The 12 code will flash three times. The next code is the first error code. It will also flash three times. Record all of the codes until the 12 is flashed again. That means that all of the codes have been flashed and that the system has looped to the beginning of the list. The codes will be displayed in numerical order, not in order of occurrence.

To clear the stored codes plug the jumper in for two seconds and remove it for two seconds, do the cycle two more times, for a total of three cycles, leaving the jumper in at the end. If successful the lamp will stop blinking and remain on. The timing is critical for success. It may help to connect a switch to two wires and use the switch in conjunction with a clock to aid in timing the cycles.

There is a bug in the error logging software. If an error code is present for many many ignition on cycles. The system will list all possible error codes. If this happens, clear the codes. Then turn the ignition on. The code or codes set after one ignition cycle will be valid.

Note that the Service Ride Control light will stay on if the ignition is turned on three times and the car is not driven. A code 23 speedometer error will set. The light will go out and the code will clear automatically once the car is driven 3 mph.