Re: Temp gauge on a murcruiser 170 not working........3.7
I fixed mine by replacing water temp sending unit and fixing broken wire.
Mine is old style 470 with thermostat under coolant reservoir.
To test gauge:
1. remove send wire
2. turn ignition on - gauge should show 0
3. ignition off
4. jumper send terminal to ground
5. turn ignition on - gauge should show max temp
if gauge tests out ok, check wiring:
take a long wire - enough to run from gauge to the sender. Test its continuity with multimeter.
disconnect wire from sending unit and gauge. using long wire connected to sending unit end of wiring and check continuity.
If wiring is good replace temp sending unit.
