Table of contents: Basic information and safety… ↓ Engine management system, data… ↓ Safety precautions when working with… ↓
Basic information and safety precautions
The ignition system ignites the air-fuel mixture supplied to the combustion chambers of the cylinders of gasoline engines. To form a spark of the required intensity, the 12-volt voltage of the on-board network is converted into high-voltage voltage in the ignition coils. On 1.6 l engines, an ignition module is used, connected by high-voltage wiring to the spark plugs. On other engines, a separate ignition coil is used for each spark plug, installed directly on the plug, high-voltage wires are not used. The electronic ignition system is an integral part of the gasoline engine management system. Its main working components are spark plugs and ignition coils. The supply of high-voltage voltage to the spark plugs is controlled by the electronic engine control module (ECM). Manual adjustment of the ignition timing and idle speed is not performed - if the required settings are violated, the failed components must be replaced. The components of the ignition system are not subject to wear and do not require regular maintenance. In accordance with the maintenance schedule, only the spark plugs must be replaced (see Chapter 1).
The preheating system of diesel engines is designed to preheat the combustion chambers for the purpose of confident ignition of diesel fuel. Glow plugs are used as heating elements, the operation of which is controlled by the corresponding electronic unit based on signals from the EST, SKR and SMR sensors.
Engine management system, data transmission buses
Basic information about the operation of the engine management system and its sensors is presented in Chapter 4.
In modern vehicles, individual components and control units are connected into a network by CAN data buses (Controller Area Network). Messages and signals can be transmitted over these buses. Each control unit connected to the network reads only those messages and signals that are important to it.
The data bus is a twisted cable of two wires with a cross-section of 0.35 or 0.5 mm². One of these wires has orange insulation. The purpose of this data bus can be determined by the color of the insulation of the second wire:
- black - CAN High, powertrain;
- green - CAN High, comfort devices;
- purple - CAN High, communication and information devices;
- brown - CAN High, all devices.
The length of one turn should be 20 mm. When repairing one of the wires, a straight section of at least 50 mm is made. Both wires should have the same length.
Safety precautions when working with ignition and fuel injection control systems
To prevent injury and/or failure of electrical and electronic system components, the following must be observed:
- do not touch or disconnect the ignition system wiring while the engine is running/starter is rotating;
- disconnect/connect fuel injection control system lines, ignition system wiring, as well as any diagnostic and measuring equipment only with the ignition off;
- before performing welding work, the negative cable from the battery and the additional battery must be disconnected (if available);
- maintenance work on the electronic ignition system is not permitted for people with an implanted pacemaker.
(This article was previously published on the resource AUDIMANUAL.RU)