engine rpm signal failure

The engine uses two engine speed/timing sensors. One sensor picks up the camshaft gear and the other sensor picks up the crankshaft gear. Both of the engine speed/timing sensors detect the reference for engine speed and timing from a unique pattern on the gear. The ECM counts the time between pulses that is created by the sensor as the gear rotates in order to determine rpm.
Under normal operation, the secondary engine speed/timing sensor is used to determine timing for starting purposes. The secondary engine speed/timing sensor is used to determine when the piston in the No. 1 Cylinder is at the top of the compression stroke. When the timing has been established, the primary engine speed/timing sensor is then used to determine engine speed.
After locating the No. 1 cylinder, the ECM triggers each injector in the correct firing order and at the correct unit injector timing. The actual timing and duration of each injection is based on engine rpm and load. If the engine is running and the signal from the primary engine speed/timing sensor is lost, a slight change in engine performance will be noticed when the ECM performs the changeover to the secondary engine speed/timing sensor. Loss of the signal from the secondary engine speed/timing sensor during engine operation will not result in any noticeable change in engine performance. However, if the signal from the secondary engine speed/timing sensor is not present during start-up the following conditions may exist:

• The engine may require a slightly longer period of time to start-up.
• The engine may run rough for a few seconds until the ECM determines the proper firing order by the use of the primary engine speed/timing sensor only.

The engine will start and the engine will run when only one sensor signal is present from either of the sensors. The loss of the signal from both of the sensors during engine operation will result in the termination of injection and the shutting down the engine by the ECM. The loss of the signal from both of the sensors during start-up will prevent the engine from starting.

Your Primary speed sensor or wiring located LH Side of front cover down by sump could be faulty, or the wiring from the ECM to it,
Also it could be the secondary sensor located LH side of front cover behind compressor. you need to connect ET to varafi weather the code is 64-12 or 190-12

 

a leaking front crank seal or front cover will let the oil deteriorate the wire insulation and the wires to the crank position sensor will break. you need either the cam signal or the crank signal to run, if you unplug the cam sensor and the engine will not start the issue is the crank sensor and vice versa. this is only if one of the two sensors has completely failed and the ecm is not seeing the signal