Saab Problems? Ask a Mechanic for Answers ASAP
The problem you are experiencing is usually caused by the ignition cassettes or engine speed sensor, in order to isolate the problem
down the following test will need to be done,
Test for power to the ignition cassettes on pin 10 (Green/Black). Should have battery voltage with the ignition on or starting.Pin 6 (Black) should have constant ground.Pins 1, 2 and 3 on each cassette are the input coil trigger signals from the Trionic Engine Control Module (ECM). A lab scope will show a 12V reference with a square-wave pulse to ground as the signal. A logic probe or other low-voltage Light Emitting Diode (LED) test light will show alternating Red (power) and Green (ground) lights during cranking.If power, ground and signal inputs are good, replace the ignition cassette.If signal inputs (ground pulses) are missing, test the engine speed sensor output between the Yellow and the Black wires. It should produce an AC voltage signal during cranking. A meter should show 1V AC or higher and a lab scope should show a sine-wave pattern, 2V peak-to-peak or higher.
They use the rear wheel sensors, I am 99% sure they are using the left rear wheel sensor as the engine speed sensor, can confirm that Monday when I get back to work.