Temperature Gauge Quick-Check
A quick-check of the coolant temperature sender can be made to determine the cause of an incorrectly reading temperature gauge. The checks should be made at the coolant temperature sender on the front of the cylinder head, below the distributor. See Fig 1 .
Disconnect the wire from the sender and hold it to ground. Turn the ignition on. If the gauge needle moves upward, the sending unit is faulty. If the gauge does not respond, the wiring to the gauge is broken (open circuit) or the gauge itself is faulty. To check the resistance of the sender, measure between ground and the sender terminal with the wire disconnected. See COOLING SYSTEM SPECIFICATIONS .
NOTE:
When replacing a faulty coolant temperature sender, drain the cooling system below the level of the sender and then unscrew the sender.