Yamaha YZF-R125 Service Manual: Checking the ignition coil

1. Check:

Primary coil resistance Out of specification  Replace.


a. Disconnect the ignition coil connectors from the ignition coil terminals.

b. Connect the pocket tester ( × 1)
to the ignition coil as shown.


Positive tester probe
red/white "1"

Negative tester probe
orange "2"

Checking the ignition coil


c. Measure the primary coil resistance.

2. Check:

Secondary coil resistance Out of specification Replace.


 a. Disconnect the spark plug cap from the ignition coil.

b. Connect the pocket tester ( ×
1k) to the ignition coil as shown.


  • Positive tester probe
    orange "1"
  • Negative tester probe
    spark plug lead "2"

Checking the ignition coil


c. Measure the secondary coil resistance.

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