Diagnosis And Testing-Engine Block Heater

If the unit does not operate (Fig 1 ) or (Fig 2 ), possible causes can be either the power cord or the heater element. Test the power cord for continuity with a 110-volt voltmeter or 110-volt test light. Test heater element continuity with an ohmmeter or a 12-volt test light.

CAUTION: To prevent damage, the power cord must be secured in it's retainer clips and away from any components that may cause abrasion or damage, such as linkages, exhaust components, etc.

Fig 1: Engine Block Heater - 4.0L Engine

Courtesy of DAIMLERCHRYSLER CORP.

Fig 2: Engine Block Heater - 4.7L Engine

Courtesy of DAIMLERCHRYSLER CORP.