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Home >> GMC >> 1990 >> Forward Control 6.2 J, Automatic, 475/M40 >> Repair and Diagnosis >> Accessories & Equipment >> Gauges & Instrument Panels >> Instrument Panel - Standard & Electronic >> Description & Operation >> Coolant Temperature Gauge Operation >> All Models

All Models

Coolant temperature gauge measures electrical current resistance from coolant temperature sending unit mounted in cylinder head. Sending unit has a resistance of 55 ohms at 260°F (127°C) and a resistance of 1400 ohms at 100°F (38°C). As coolant temperature increases, current flow through sending unit to gauge increases due to less resistance, causing gauge pointer to move toward HOT.