7.1.2. Checks of a control system of ignition

See also Section Diagnostics of Malfunctions in Introduction at the beginning of the Management.

General information

Components of systems of ignition/engine management are among elements of the increased reliability and the majority of refusals, as a rule, are connected with violation of quality of contact connections, or damage of an electrical wiring. Breakdowns of VV of an electrical wiring most often result from pollution, moistening or damage of isolation. Before coming to conclusion about failure any of system elements, always first of all check a condition of the corresponding electrical wiring and its contact connections.

You do not make check of serviceability of giving of tension on spark plugs by a detachment from them of an electrical wiring and its approbation on the mass of the engine, - such diagnostics, besides risk of receiving an electroshock, it is accompanied by danger of failure of ECM or the coil of ignition. At violation of stability of working turns of the engine it is also not necessary to try to localize malfunction by a consecutive detachment of an electrical wiring from spark plugs.

The listed below checks allow to define the reason of malfunctions which symptoms are rather obvious (refusal of a starter, admissions of ignition, etc.). Some, less obvious, violations can not show themselves due to automatic transition of a control system to emergency operation of functioning and are shown only in increase in fuel consumption, violation of stability of turns of idling, reduction of efficiency of return of the engine, emergence of detonations and so forth, - address for consultations specialists of car service.

The engine is not started

Do not forget that failure of an immobilizer of the anti-theft device can be a cause of failure of start of the engine.


  1. Check a condition of a safety lock of ignition (see the Head Onboard electric equipment), in case of need make its replacement.
  2. If the starter is not turned, or rotates the engine too slowly, first of all check serviceability of functioning actually of a starter, and also a condition of the rechargeable battery. Connect the voltmeter to plugs of the battery and measure its output tension at an engine provorachivaniye by a starter, - if the result of measurement makes less than 9.5 In, it is necessary to check serviceability of a condition of the battery, a starter and components of system of a charge.

Do not activate a starter continuously within more than 10 seconds!

  1. Working strictly according to instructions of the manufacturer, connect a stroboscope and turn the engine a starter, - activation of a lamp of a stroboscope confirms serviceability of giving of VV of tension on spark plugs. Check a condition actually of candles. If the stroboscope does not work, estimate an electrical wiring VV condition (see the Head the Current leaving and service).
  2. In the absence of sparking make sure of serviceability of the coil(s) of ignition (simplest to replace the coil obviously serviceable, - alternatively to measure resistance of windings). You do not hurry to throw out the coil suspected of refusal, - before check quality and reliability of its contact connections.
  3. Violation in the powerful buffer output cascade which is a component of the module of management of the engine (ECM) and also malfunction of any of information sensors of a control system (CMP/CKP), or other accompanying knot can be one more cause of failure of start of the engine, - check memory of ECM for existence of the diagnostic codes which are written down in it (see Power supply systems, managements of engine/decrease in toxicity of the fulfilled gases and production of the fulfilled gases).

Admissions of ignition


  1. Violation of quality of contact connections of an electrical wiring on plugs of coils of ignition, or any of information sensors (CMP/CKP) appears the reason of admissions of ignition most often.
  2. Switch off ignition and check the corresponding contact sockets for existence of signs of oxidation and reliability of fixing on plugs.
  3. Estimate an electrical wiring VV condition. Make sure that wires do not adjoin to metal parts of the engine, - if the wire with the broken isolation concerns metal, then during the operation of the engine sparking will take place not between contacts of the corresponding spark plug, and in the place of breakdown. At identification even of insignificant damage of isolation at least of one of wires replace all set.

It is the simplest to make sure of serviceability of a condition of VV of an electrical wiring by replacement of all set by obviously serviceable.

  1. At a serviceable electrical wiring failure actually of a candle, or bobbin assembly can be the reason of admissions of ignition, - replace candles (see the Head the Current leaving and service), check a condition of the coil. Damage or pollution of the sensor of provision of a bent shaft (CKP) can be one more cause of admissions of ignition.
  2. In conclusion make reading of the DTC codes and cleaning of memory of the module of onboard self-diagnostics (ECM).