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Engine Speed Sensor: Testing and Inspection

STATIC TEST

Engine Sensor Connector Bracket And Connector Terminal ID:






1. Unplug engine speed sensor harness connector (identified by gray grommet on connector halves).

2. Check resistance between terminals # 1 and # 2 of sensor 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 turned OFF, disconnect ECM connector and check continuity of circuits between ECM terminals # 48, & # 47 and sensor harness connector terminals # 1, # 2, respectively (should be continuous). Also check continuity between sensor harness connector terminal # 3 and both engine ground and ECM terminal # 19 (circuit from sensor terminal # 3 should have continuity to both ECM terminal # 19 and engine ground).

5. Check clearance between sensor tip and teeth of flywheel.
^ Clearance should be 1.10mm (0.043").

6. Check for excess accumulation of metal shavings or other ferrous material on the sensor tip.

If no problems have been found, but a code 2111 was displayed, then there is a poor connection at the ECM or the ECM is faulty.

DYNAMIC TEST

Engine Speed Sensor Signal:






The engine speed 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 a flywheel tooth passes the sensor tip which, when viewed on a scope, approximates a sine wave. The wave pattern should look similar to 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.