Models Produced Before March 1990
STATIC TESTEngine Sensor Connector Bracket And Connector Terminal ID:
1. Unplug harness connector from crank position sensor lead (black connector on bracket).
2. Check resistance between terminals #1 and #2 of male connector.
^ Resistance should be approx. 1K ohms. If not, replace sensor.
3. Check resistance between terminals #1 and #3, and between terminals #2 and #3 of sensor connector.
^ Resistance should be infinite (no continuity). If there is any continuity (even if resistance is very high) replace sensor.
4. With ignition OFF, disconnect ECU harness connector B and check for continuity in circuit between ECU terminal 12B and sensor harness connector terminal #1 (should be continuous and not grounded). Check also for open sensor ground circuit between ECU terminal 24B and sensor harness connector terminals #2 and #3 (should have continuity to both sensor terminals #2 & #3 from ECU terminal 24B). Repair if necessary.
^ If there is no continuity in any of the wires to the ECU from sensor, check to make sure the connectors for the engine speed sensor (black connector) and crankshaft position (reference) sensor (gray connector) are not mixed up (plugged into the wrong sensor).
5. Check clearance between sensor tip and reference pin in flywheel.
^ Clearance should be 1.10mm (0.043").
If no problems have been found, but a code 2112 was displayed, check distributor basic adjustment and hall sensor. If these also check out OK, then the ECU is faulty.
DYNAMIC TEST
Crankshaft Position (Reference) Sensor Signal:
The crankshaft position sensor can be tested dynamically with the use of an oscilloscope. When the engine is running, the sensor will produce an alternating current wave pulse each time the reference pin passes the sensor tip. The wave pattern should look like that shown in the diagram, and can be observed on a scope by probing terminals #1 and #2 of the sensor connector (use appropriate break-out box or parallel connector test leads).
Many automotive oscilloscopes are designed only to display primary and secondary ignition patterns and are not able to perform this type of test. To find out if your scope has this capability, or for correct procedures on hooking up a scope see the manufacturers instructions for your particular scope.