Reading and Clearing Diagnostic Trouble Codes

In the event of a PGM-FI system electrical malfunction, a dash mounted indicator lamp will light and stay lit. If the dash warning lamp is on, or if a system malfunction is suspected even though the lamp is off, it is necessary to check the electronic control unit LED display. The LED display is on the ECU, and the indicator lamps operate whenever the ignition is on and a trouble code is stored in the ECU memory.
On Civic, CRX and 1985 Accord, the ECU contains four LED's, numbered 1, 2, 4 an 8 when counted from right to left. When the warning lamp on the dash is lit and a failure code is stored in the ECU memory, the LED indicators will be illuminated to indicate the failure code.
On 1986-88 Accord and Prelude a single LED is used. When an abnormality is detected the LED display on the ECU blinks. The LED blinks a certain number of times, with the number of blinks indicating the number of the failure code. After the LED blinks a number of times there will be a 2 second pause and the LED will blink out the number of the next failure code.