Checking Cold Mixture Heater (CMH) Resistance

1. To measure CMH resistance, unplug wiring connector. Using an ohmmeter, measure resistance between CMH connector terminals. On Corolla and Tercel, resistance should be .5-2.2 ohms at 68°F (20°C).
2. On Pickup, measure CMH resistance between CMH connector positive terminal (Blue/Yellow wire) and ground. CMH type "A" resistance should be .35-1.0 ohms at 68°F (20°C). CMH type "B" resistance should be .5-2.0 ohms at 68°F (20°C). See Fig 1.

Fig 1: Checking Cold Mixture Heater Resistance (Pickup)

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