Content .. 13 14 15 16 ..

KTM LC4 400-660LC42003 engine. Manual - part 15

7-27D

Ignition system

From the battery

the battery voltage is conducted via the main fuse

through the ignition lock

and the emergency OFF switch

which are both ON, to the side stand relay

The side stand relay conducts the battery voltage to the CDI unit

, if

at least one of the following requirements is met :

● The side stand is up (side stand switch closed).

● The transmission is switched to neutral (neutral switch closed).

● The clutch is pulled (clutch switch closed).

The pulse generator

transmits a signal to the CDI unit

upon every

rotation of the crankshaft. In the CDI unit, the ignition point is
computed from this signal.
The ignition pulse is transmitted to the ignition coil

(i.e. an ignition

spark is generated).

NOTE: The ignition system is a digital high voltage capacitor ignition
that receives its power supply from the battery. Therefore, it works only
with an intact battery.
When the battery is discharged below the threshold level, the voltage
can, due to the starting process, drop below the minimum supply
voltage required by the ignition.

CAUTION

AFE AND FAULTLESS OPERATION OF THE DIGITAL IGNITION REQUIRES SPARK PLUG

CONNECTORS AND SPARK PLUGS WITH INTEGRATED RESISTANCE TYPE SUPPRESSORS

bl  . . . . . . . . .blue
br  . . . . . . . . .brown
ge  . . . . . . . .yellow
gr  . . . . . . . . .grey
g   .  . . . . . . . .green
o  . . . . . . . . .orange
r   .  . . . . . . . . .red
ra  . . . . . . . . .pink
s . . . . . . . . . .black
v  . . . . . . . . .violet
w  . . . . . . . . .white

Battery

Main fuse

Ignition lock

Emergency-off switch

Auxiliary relay

CDI

Pulse generator

Ignition coil

Side stand switch

ge-bl

s-r

r-s

Repair manual KTM LC4

Art.-Nr

. 3.206.006 -E

7-28D

CDI unit

Check the cables and plug and socket connections of the CDI unit

The CDI unit function can only be checked on an ignition test bench.

CAUTION

EVER USE A COMMERCIAL MEASURING DEVICE TO CHECK THE

CDI

UNIT

OMMERCIAL MEASURING DEVICES CAN DESTROY HIGHLY SENSITIVE ELECTRONIC

COMPONENTS

Check ignition coil

– Disconnect all cables and remove the spark plug connector.
– Use an ohmmeter to measure the following values.

NOTE: The indicated setpoint values correspond to a temperature of
20° C.

Replace the ignition coil if the measured values deviate significantly
from the setpoint values.

Spark plug connector

– Check the spark plug connector for cracks and fissures.
– Measure spark plug connector resistance.

Setpoint value: 3.0 – 7.5 kΩ

Checking the side stand relay

Preparation:
– Remove the seat, the right side cover and the headlight mask.
– Disconnect the power supply from the CDI (orange cable).
– To check the current status of the relay connect the orange cable

coming from the cable tree either to the positive line of a voltmeter
or to a test lamp.

– The negative line of the voltmeter or test lamp is connected to

ground.

– Switch on the ignition lock and the emergency OFF switch.

Perform the following tests in the order indicated below:
– The relay must connect in either of the following three cases:

● Put a gear in but do not pull the clutch. Slowly swing up the side

stand. When the side stand is approximately halfway up, the side
stand relay should respond. If this is not the case, please check the
relay, the side stand switch

as well as the corresponding parts of

the cable tree.

● With the side stand down and a gear put in, slowly pull the clutch

lever. The side stand relay should respond when the lever is pulled
approximately half of the overall distance. If this is not the case,
please check the diode in the connector with the yellow and the pink
cable and the neutral switch.

● With the side stand down and the clutch not pulled, switch the

transmission to neutral. The relay should connect when the
transmission is switched to neutral and be tripped when a gear is
put in. If this is not the case, please check the diode in the connector
with the yellow and the green/black cable and the neutral switch.

NOTE: Responding of the relay is accompanied by a faint clicking sound
and the CDI’s power supply is switched on. The voltmeter or the test
lamp indicates a battery voltage. After testing, reconnect the CDI unit’s
power supply (orange cable).

RESISTANCE

0,425 – 0,575 Ω

10,80 – 16,20 kΩ

MEASUREMENT

primary coil

secondary coil

COLOURS

blue/white – ground

blue/white – ignition wire

7-29D

Checking the side stand switch

– Disconnect the 2 connectors connecting the side stand switch

with the cable tree (below the tank).

– Connect an ohmmeter to the side stand cable.
– Slowly swing up the side stand.
– The switch must be open while the side stand is down.
– The side stand switch must connect when the side stand is

approximately halfway up.

– If this is not the case, replace the side stand switch.

CAUTION

EVER SHORT

CIRCUIT THE SIDE STAND SWITCH SO AS TO BE ABLE TO DRIVE ON

HIS WOULD DEACTIVATE THE IGNITION CUT

OFF WITH THE SIDE STAND DOWN

AND YOUR MOTORCYCLE WOULD NO LONGER COMPLY WITH THE APPLICABLE
SAFETY STANDARDS

NOTE: If the side stand is removed, for example when subsequently
installing a center stand, the two connectors of the cable tree that lead
to the side stand switch must also be connected.

Trouble shooting in the ignition system

Before checking the ignition system check
● if the ignition lock is in position
● if the emergency off switch is in the position
● if the neutral control lamp is on
● if the motorcycle can be started with the clutch pulled
● if the battery is charged
● the main fuse

Check if an ignition spark is produced when the starter is operated.
Proceed as follows:
– Pull the spark plug connector.
– Disconnect the spark plug connector from the ignition cable.
– Hold the free end of the ignition cable approximately 5 mm from

ground.

– A strong spark should be visible when the electric starter is now

operated. If the battery is discharged below the threshold level
required for electric starting, please use the kickstarter.

– If a spark is visible, replace the spark plug connector.
– Twist out the spark plug and insert it into the spark plug connector.
– Connect the spark plug to ground. A strong spark should be visible

at the electrode when the electric starter is now operated. If this is
not the case, the spark plug connector or the spark plug is defect.

– If no spark is produced during the first test, perform the following

checks:

● Does the ignition’s power supply line (orange) carry battery voltage?

● If this is not the case, check the ignition lock, the emergency off

switch and, if applicable, the side stand relay as well as the
corresponding parts of the cable tree.

– If the ignition is sufficiently supplied with power and no spark is

produced, check:

● ground connection of CDI unit and ignition coil
● the cable between CDI unit and ignition coil
● pulse generator
● stator
● ignition coil

Repair manual KTM LC4

7-30D

Art Nr 320549-D

Checking the voltage regulator-rectifier

– Start the engine and switch on the low beam.
– Connect a voltmeter to the two terminals of the capacitor (red/white

cable = positive, brown cable = negative).

– Accelerate the engine to a speed of 5000 r.p.m. and read off the

voltage.

Nominal value: 14.0 - 15.0 V

If the reading significantly deviates from the nominal value above,
check the capacitor. If the capacitor is intact, replace the voltage
regulator-rectifier.

Checking the capacitor

– Discharge the capacitor by bridging the two terminals with a

screwdriver and remove.

– Connect the negative pole of a 12V battery with the negative

terminal of the capacitor. The connection between the positive pole
of the battery and the positive terminal of the capacitor (marked +)
is made with a test lamp

– When the power circuit is closed, the test lamp must begin to light

up. As capacitor charging increases, the brightness of the test lamp
must decrease.

– The test lamp must go out after 0,5-2 seconds (depending on the

lamp capacity).

– If the test lamp does not go out or does not light up at all, the

capacitor is faulty.

CAUTION

ISCHARGE THE CAPACITOR BEFORE AND AFTER EACH TEST

HEN

INSTALLING

THE

CAPACITOR

MAKE

SURE

THAT

THE

TERMINALS

ARE

CONNECTED IN ACCORDANCE WITH THEIR MARKINGS

. C

ONNECT RED

WHITE CABLE

TERMINAL

ELECTRICAL – SXC ‘99

Checking the voltage regulator (Kokusan)

A defect voltage regulator can cause different kinds of trouble:

● No voltage in the circuit

In this case, the voltage regulator must be disconnected at idle
speed. The voltage regulator is defect if the power consumers now
work properly.
If the power consumers are still not supplied with power, the switch,
the wiring harness or the ignition system must be checked for
defects.

● Excessive voltage in the circuit

The bulbs burn out. In this case the voltage regulator must be
replaced.

Checking the capacitor

– Discharge the capacitor 1 by bridging the two terminals with a

screwdriver and remove.

– Connect the negative pole of a 12V battery with the negative

terminal of the capacitor. The connection between the positive pole
of the battery and the positive terminal of the capacitor (marked +)
is made with a test lamp

– When the power circuit is closed, the test lamp must begin to light

up. As capacitor charging increases, the brightness of the test lamp
must decrease.

– The test lamp must go out after 0,5-2 seconds (depending on the

lamp capacity).

– If the test lamp does not go out or does not light up at all, the

capacitor is faulty.

CAUTION

ISCHARGE THE CAPACITOR BEFORE AND AFTER EACH TEST

HEN

INSTALLING

THE

CAPACITOR

MAKE

SURE

THAT

THE

TERMINALS

ARE

CONNECTED IN ACCORDANCE WITH THEIR MARKINGS

. C

ONNECT RED

WHITE CABLE

TERMINAL

Check ignition coil

– Disconnect all cables and remove the spark plug connector.
– Use an ohmmeter to measure the following values.

NOTE: The indicated setpoint values correspond to a temperature of
20° C.

Replace the ignition coil if the measured values deviate significantly
from the setpoint values.

7-30

ELECTRICAL – SC ‘99

RESISTANCE

0,425 – 0,575 Ω

10,80 – 16,20 kΩ

MEASUREMENT

primary coil

secondary coil

COLOURS

blue/white – ground

blue/white – ignition wire

Repair manual KTM LC4

Art.-Nr

. 3.206.006 -E

7-32D

Leakage inspection

The drop test must be performed before checking the voltage
regulator/rectifier.
– Turn off the ignition and disconnect the ground wire from the

battery.

– Insert an amperemeter between the ground wire and the negative

pole of the battery.

Setpoint value: max. 1 mA

– Check for power consumers, should the measured value exceed the

indicated maximum value.
Example:

● defective voltage regulator-rectifier

● leak currents in the socket connectors, in the ignition lock or in the

starter relay.

Charging system

Generator

Regulator-rectifier

Main fuse (20 A)

Battery (12V / 8 Ah)

Capacitor

0,00

ignition

lock

start

relay

tachometer

CDI

ge-r

s-r

r-s

ELECTRICAL – DUKE ‘99

7-33D

Charging voltage / checking the voltage regulator-rectifier

NOTE: The values stated below apply only to fully charged batteries
(minimum charging level 90 %).

– Start the engine and switch on the low beam.
– Connect a voltmeter to both battery connections.
– Accelerate the engine to a speed of 5000 rpm and read off the

voltage.

Nominal value: 14.0 - 15.0 V

In the case of a significant deviation from the nominal value:
– Check the connector between the stator and the voltage regulator-

rectifier and the connector between the voltage regulator-rectifier
and the cable tree.

– Check the stator.
– Replace the voltage regulator-rectifier.

Removing the battery

– Remove the seat.
– Disconnect first the negative and then the positive pole of the

battery.

– Remove the bolts

and swing the battery support with the voltage

regulator-rectifier sideways.

– Remove the battery.
– When reinstalling the battery, connect the negative pole last.

CAUTION

OLLOW THE INSTRUCTIONS OF THE MANUFACTURER WHEN FILLING A NEW BATTERY

HE RELEVANT SAFETY INSTRUCTIONS ARE ALSO CONTAINED IN THE USER MANUAL

SUPPLIED WITH THE BATTERY

Charging the battery

– Remove the battery and check the charging level. Use a voltmeter to

measure the voltage between the battery poles (off-load voltage).

– Accurate results can only be obtained if the battery has neither been

charged nor discharged during a period of 30 minutes preceding the
measuring.

– If the battery is empty, it can be recharged for a maximum period of

10 hours at 0.8 A and a maximum of 14.4 V.

CAUTION

– T

O AVOID DAMAGE

DO NOT REMOVE THE LOCKING BAR

– A

LWAYS CONNECT THE BATTERY TO THE CHARGING UNIT BEFORE TURNING THE

CHARGING UNIT ON

– W

HEN RECHARGING THE BATTERY IN CLOSED ROOMS ENSURE SUFFICIENT

VENTILATION

. E

XPLOSIVE GASES ARE RELEASED DURING THE BATTERY CHARGING

PROCESS

– C

HARGING TIME AND CHARGING VOLTAGE SHOULD NOT EXCEED THE STATED

VALUES

. O

THERWISE ELECTROLYTE WILL BE RELEASED THROUGH THE SAFETY

VALVES

– A

VOID QUICK CHARGING IF POSSIBLE

off load voltage

charging level

charging time charging voltage

Volt

0.8 A

>12.7

100

––

~12.5

4 h

max.

~12.2

7 h

14.4 V

~12.0

11 h

~11.8

14 h

Repair manual KTM LC4

Art.-Nr

. 3.206.006 -E

7-34D

Checking the capacitor

– Pull main fuse out of the fuse holder.
– Discharge the capacitor by bridging the two terminals with a

screwdriver and remove.

– Connect the negative pole of a 12V battery with the negative

terminal of the capacitor. The connection between the positive pole
of the battery and the positive terminal of the capacitor (marked +)
is made with a test lamp

– When the power circuit is closed, the test lamp must begin to light

up. As capacitor charging increases, the brightness of the test lamp
must decrease.

– The test lamp must go out after 0,5-2 seconds (depending on the

lamp capacity).

– If the test lamp does not go out or does not light up at all, the

capacitor is faulty.

CAUTION

ISCHARGE THE CAPACITOR BEFORE AND AFTER EACH TEST

HEN

INSTALLING

THE

CAPACITOR

MAKE

SURE

THAT

THE

TERMINALS

ARE

CONNECTED IN ACCORDANCE WITH THEIR MARKINGS

. C

ONNECT RED

WHITE CABLE

TERMINAL

Content .. 13 14 15 16 ..