|
 |
|
|
|
|
Latest News Crank Angle Sensors (CAS) Questions for a Technician to think about when a Petrol or Diesel engine refuses to start and the Crank Angle Sensor is suspect of being faulty. 1. Where is the CAS located on the specific vehicle? We all know that the function of the CAS on an engine is to monitor the rotational position and speed (RPM) of the crank shaft and it affects the ignition timing, fuel injection or the injection process on a Diesel engine. The CAS location may vary depending on the type of Ignition system utilised and model of vehicle being worked on, and if Diesel or Petrol.
It is important that you have identified the suspect CAS and not the CAM sensor or a transmission input speed sensor located on the bell housing.
2. What type of CAS is fitted to the vehicle? There are generally 3 common CAS types used in the industry. MAGNETIC PICK UP COILS This type was extensively used in the past and may still be found on some later vehicles. This type produces a sign wave output and requires no external power supply. May be 2 or 3 terminal configuration - 3rd terminal is a shielded Earth.
HALL EFFECT TYPE CAS A more accurate type of CAS that has been and still is extensively used in most vehicle applications. Simplified, this system requires a power supply for Hall Sensor operation which allows a 5 Volt signal from the ECM to be switched On and Off by the shape of the reluctor ring or similar trigger method. These sensors may be located internal in the distributor or separately mounted on the engine.
The square wave digital signal is clearly visible with the use of a suitable oscilloscope. (Refer typical Commodore SIDI CAS below)
OPTICAL TYPE CAS Simplified, this system utilised a light source from an LED passing through slots in a rotating disc that is detected by a photodiode (light receiving diode) and transferred into position and speed square wave signals. Even though this system is accurate, it is important that the optical components must be kept clean to ensure its accuracy. Even though many of these CAS types are sold as a separate replaceable item, there are examples of complete assembly purchases only. Typical Optical type CAS located in Distributor.
Common typical CAS faults and the effects on engine operation. (Both Petrol and Diesel)
Typical example of fitting requirements shown below. Re-fitting the fly wheel /ring gear on a Volvo. Fit fly wheel / ring gear on crank shaft with CAS trigger dowel "A" as shown in diagram.
The Premier Auto Trade Sensor range includes more than 360 Crank Angle Sensors (CAS) from the world’s leading manufacturers, covering over 16 million vehicle applications in Australia and NZ. When you supply and fit products from Premier Auto Trade you can expect a product designed and tested to the vehicle manufacturer’s specifications offering OE form, fit and function. Premier Auto Trade distributes products throughout Australia via a network of specialised resellers and leading automotive groups.
|
Latest News
Tech Tips - Wheel Speed Sensors (WSS) |
|
| privacy statement terms of use terms and conditions sitemap news |  |
|