Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Engine Speed Signal Control
Multi-pulse wheels with different polarities are installed to the crankshaft at intervals of crank angle 6°. Since the Crankshaft Position Sensor is installed opposed to the multi-pulse wheel, pulse signals of 5 V and 0 V are generated during the rotation of crankshaft. In addition, the multi-pulse wheels have polarities at intervals of crank angle 18° to completely match the crank position.
ECM transmits a short-resistant engine speed signal via CAN communication based on a signal of Crankshaft Position Sensor.
- Detection of rotation direction: When the engine stops or temporarily rotates in the opposite direction immediately before stopping, a pulse signal of the Crankshaft Position Sensor changes. Since ECM detects the change in rotation direction through the above mechanism, crankshaft angle position can be accurately detected any time.
- When ECM cannot receive a Crankshaft Position Sensor signal, ECM uses an Intake Camshaft Position Sensor signal or Exhaust Camshaft Position Sensor signal to enable the vehicle to be driven.
- When ECM cannot receive an Intake Camshaft Position Sensor signal, ECM uses an Exhaust Camshaft Position Sensor signal to detect the position of the top dead center of Cylinder 1. When both Camshaft Position Sensor signals cannot be received, ECM performs ignition and injection to execute an emergency start after detecting crank angle 360°.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
Rather have a pro handle this?
A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.
No obligation. See pricing before you book.