Operation CHARM: Car repair manuals for everyone.

Temperature Gage

The Temperature Gage is also operated by two coils. Battery voltage is applied to both coils. One is grounded directly and the other is grounded through the Engine Temperature Sender. This has 55 ohms resistance at 123° (260°F) (hot coolant) and its resistance becomes greater at low temperatures. it is approximately 1400 ohms at 47° (1OO°F). This causes the current through the Sender to increase as the coolant temperature increases which moves the pointer.