Ignition System Testing; Ignition Coil Testing - Bosch FIX 7677 Mode D'emploi

Ignition System Testing

The ignition system is responsible for providing the spark that ignites the fuel in the cylinder.
Ignition system components that the digital multimeter can test are the primary and
secondary ignition coil resistance, spark plug wire resistance, hall effect switches/sensors,
reluctance pick-up coil sensors, and the switching action of the primary ignition coil.

Ignition Coil Testing

This test measures the resistance of the
primary and secondary of an ignition
c o i l . T h i s t e s t c a n b e u s e d f o r
distributorless ignition systems (DIS)
provided the primary and secondary ig-
n i t i o n c o i l t e r m i n a l s a r e e a s i l y
accessible.
Test Procedure:
1. If engine is HOT let it COOL down
before proceeding.
2. Disconnect ignition coil from ig-
nition system.
3. Insert BLACK test lead into COM
test lead jack (see Fig. 24).
Fig. 24
4. Insert RED test
l e a d i n t o
lead jack.
5. Turn multimeter
rotary switch to
200Ω range.
6. Touch RED and
BLACK multim-
e t e r l e a d s t o -
gether and view
r e a d i n g
display.
Secondary
Red
Typical Cylindrical
Ignition Coil
Fig. 25
test
o n
7. Connect test leads.
• Connect RED test lead to primary
ignition coil positive (+) terminal.
• Connect BLACK test lead to primary
ignition coil negative (-) terminal.
• Refer to vehicle service manual for
location of primary ignition coil ter-
minals.
8. View reading on display.
Subtract test lead resistance found
in Step 6 from above reading.
9. If vehicle is DIS, repeat Steps 7
and 8 for remaining ignition coils.
Coil
Black
Primary
19
10. Test Results - Pri-
mary Coil
• Typical resistance
range of primary
ignition coils is 0.
3 - 2.0Ω.
• Refer to vehicle
service manual
for your vehicles
Coil
resistance range.
11. Turn multimeter
rotary switch to
200KΩ range (see
Fig. 25).
Secondary
Coil
Red Black
Typical Cylindrical
Ignition Coil
Primary
Coil