VIDEO

Informace

Cadillac

Cadillac P1A21

See the basic definition of a diagnostic error. This will help you to clarify the main causes of the fault code. You will understand the program of the control unit
Basic DTC analysis according to OBD2 protocol standard.

OBD2 or On-Board Diagnostics displays messages for basic group styles. More comprehensible code composition has been standard since 2000. The DTC code consists of five characters and its composition will be shown in this video

Insight into programming

The basic unit for the operation of any computer is the bit. Logic 0 and 1 are expressed by a single bit. Diagnostics The error code is composed of 16 bits. The first two bits define one of the four basic circuits. The video will show you a comprehensive overview of the composition of the error report

A diagnostically understandable description of the Diagnostic Trouble Code

Cadillac P1A21

Basic error definition

Wheel Speed Signal, Left Front Wheel. Faulty Signal

Cause of DTC

The DSA control module receives wheel speed signals from the ABS control module. The ABS control module converts the wheel sensor AC signal into a pulsed signal for the DSA control module. The signal is pulsed between approximately 0 V and battery voltage. It has a fixed pulse ratio (%duty ≈ 50 %) where the frequency changes with the wheel speed. Depending on the current wheel speed signal, DTCs DSA-311, DSA-312, DSA-313 or DSA-314 are stored if the vehicle speed exceeds 8 km h and the DSA control module registers that: Wheel speed increase or reduction is too great. The speed of a wheel is less or the same as half the speed of one of the rear wheels. The speed signal varies considerably.