Temp Switch Questions

[BoatDr]

I'm currently rebuilding a 1979 Evinrude 115 and when I pulled the head covers, I discovered that the port temp switch had completely rusted out and the starboard side has a little bit of rust on it. First, what do these do? Second, how do I test the starboard switch to see if it's still functional.

 

[boobie]

Re: Temp Switch Questions

They set off your horn if the mtr overheats. If you're doing a rebuild I'd just replace them. Cheap insurance.

 

[BoatDr]

Re: Temp Switch Questions

Where is the alarm? I've never heard it, and I'm pretty sure the starboard side was damaged from overheating.

 

[boobie]

Re: Temp Switch Questions

Should be in your control box or under the dash. To test it you disconnect the temp switch (tan) wires and ground out the wiring harness wires with the key in the on position and the horn should sound. If not you got horn or wiring probs.

 

[BoatDr]

Re: Temp Switch Questions

Thanks. I'll have to take a look in the control box...I know for certain it's not under the dash. I'm looking at replacement switches online and a lot of them have two leads instead of the single tan wire on the old switches. Is the second lead just a ground that I can attach to any of the head cover bolts?

 

[boobie]

Re: Temp Switch Questions

If the new switches have a tan wire and a black wire with a ring terminal, the black lead goes to ground. Any temp switches with a white/black lead are for QS.

 

[wmconway]

Re: Temp Switch Questions

Did OMC have quickStart in 1979?

 

[boobie]

Re: Temp Switch Questions

No. But if you're shopping around you never know what somebody will try to sell you by mail.

 

[edfishing2]

Re: Temp Switch Questions

If you get to the point of testing the temp switch (head cover removed) you can heat up some cooking oil (with thermometer) and hook up switch to a multimeter (or test light). Mine was single tan wire type. One lead of meter goes to tan wire and other end of meter touches housing. I added large aligator clip to jumper wire to go from the housing to meter. With this and some hot oil just dip the side of the sensor housing into the oil and at (IF working right) right temp it will make an audible click and your meter (or test light) will show (makes the circuit) contiuity. Then pull back out of hot oil and click again and it breaks the circuit.

All the sensor does in a nut shell is ground out the tan wire to the block.