Specifications

Service Training
Section 4.9
Page 12
12.05
FUNCTIONING OF THE TRANSISTOR COIL IGNITION (TSZ)
The a.c. control voltage delivered by the induction generator is converted into rectangular pulses in the
switchgear. These pulses control the switching on and off of the primary coil current and thus the induction
of the high voltage in the secondary winding of the ignition coil.
NOTES: At this point we would point out that the switchgears of the TSZ are only safe in certain
circumstances from polarity reversal from switching. For instance, an incorrect connection of
the battery to the [truck’s] power supply system must be detected and corrected within a few
seconds, otherwise there is a danger that the electronics will be damaged.
The plug-in connections on the switchgear and on the ignition distributor are made in such a
way that they can only be fitted with the correct polarity (moulded plugs). Therefore no polarity
reversal is to be feared because of these components.
As a rule, electronic ignition systems have higher ignition power than traditional ignition
systems. Electronic ignition systems work in a power range that is potentially lethal if bare
terminals and voltage-carrying parts are touched. This applies both to the low voltage parts
(primary current circuit) and the high voltage parts (ignition circuit) of such equipment.
When working on the ignition system, the ignition must always be switched off or the power
source to be disconnected. Such operations include:
- Changing of parts such as spark plugs, ignition coils or transformers, distributors, cables, etc.
- Connecting of engine test devices such as timing lights, dwell-tachometers, ignition oscillo-
scopes, etc.
If it is necessary to switch on the ignition in order to work on the ignition system or the engine,
dangerous voltages occur in the whole ignition system both in its components and in the wiring
harness, as well as in the diagnostic connector, the tachometer connection, the plug
connections and the test equipment.
So: TAKE CARE WHEN WORKING ON ELECTRONIC IGNITION SYSTEMS!!!