GS300 & Is300

Remove ignition coil. See IGNITION SYSTEM in REMOVAL & INSTALLATION - EXCEPT GX470 article.
Using ohmmeter, check ignition coil primary resistance between positive (+) and negative (-) electrical terminals on ignition coil. See Fig 1. Replace ignition coil if ignition coil primary resistance is not within specification. See IGNITION COIL RESISTANCE (OHMS) table.

Using ohmmeter, check ignition coil secondary resistance between electrical terminal and spark plug terminal on ignition coil. See Fig 2. Replace ignition coil if ignition coil secondary resistance is not within specification. See IGNITION COIL RESISTANCE (OHMS) table. Reinstall ignition coil.

IGNITION COIL RESISTANCE (OHMS)

Application

Primary

Secondary

GS300 & IS300

Cold ⁽¹⁾

.33-.52

8500-14,700

Hot ⁽²⁾

.42-.61

10,800-17,200

⁽¹⁾	Cold is with coolant temperature of 14-122°F (-10-50°C).

⁽²⁾	Hot is with coolant temperature of 123-212°F (51-100°C).

Fig 1: Checking Ignition Coil Primary Resistance (GS300 & IS300)

Fig 2: Checking Ignition Coil Secondary Resistance (GS300 & IS300)