Checking the LED

Fault symptom
The LED does not light up.

Diagnostic procedure
1 Connect the Intelligent Saab Tester (ISAT). Select the "ACTIVATE" menu and then "LED". Activate the LED with "ON". If the diode lights up, continue fault diagnosis as described in Before Control Module Replacement.
2 If the diode does not light up, connect the BOB and disconnect the diode. Check the voltage at the control module while repeating point 1.
Measure across pin 19 of the control module connector and a good grounding point.
The voltage should be about 5 V.





3 If the resistance is OK, connect a diode tester across the diode and check that the voltage is:
- 1.6 V in the forward direction.
- OL in the reverse direction.
4 Check the wiring for continuity/shorting by measuring the resistance across:
- pin 19 of the control module connector and pin 2 of the LED connector.
- pin 1 of the LED connector and a good grounding point.
The resistance should be < 1 ohm.