In the Saab EZK distributor ignition system there is an automatic fault-tracing function. When checking the functioning or when fault- tracing, it is possible to read stored diagnostic trouble codes using a test instrument. The test instrument's LEDs (one green and one red) state any reason for a fault with flashing codes. The flashes on the green LED correspond to the "CHECK ENGINE" light's flashes and the diagnostic trouble code is found in the fault- diagnosis routines. Flashes on the red LED indicate knocking.
Connection and reading of diagnostic trouble codes
1 Connect the system tester.
NOTE: Ignition must be switched off.
2 Switch on the ignition and start the engine. Check that the LED for fault indication (green) is lit up for about 2 seconds while the starting motor is operating.
3 Let the engine run until it has reached its normal working temperature. At some point during the warming-up period the revolutions should momentarily be raised to over 2300 rpm.
4 Let the engine idle and record the number of flashes from the LEDs. Read reason for fault.