Mercruiser 165 key switch wiring?

[sledhead26]

I have a 1970 merc 165 inline 6 and was wondering if someone could tell me what wires go where on the back of the key switch. Is it a 3 or 4 prong switch? Does the switch just have a run and start function with no accessory. I looked on the diagram in the manual but it doesnt really show very well and its hard to read. Any help would be appreciated.

 

[Bt Doctur]

Re: Mercruiser 165 key switch wiring?

a 3 wire switch,, off-run - start. red or a red/orange is 12V , yellow/ red stripe is solenoid, purple is ignition and main gauges.

 

[Don S]

Re: Mercruiser 165 key switch wiring?

70 vintage is the old color coding. B terminal will be Red/white stripe, C is yellow, I is white.

 

[sledhead26]

Re: Mercruiser 165 key switch wiring?

Thats exactly what I needed. Thanks a lot

 

[sledhead26]

Re: Mercruiser 165 key switch wiring?

Ok so I thought my key switch was bad so i replaced it and nothing works still. When i hook all the wires up, i have power to the switch. As soon as I turn it to the run or start position it has zero voltage. Not sure whats going on. I tried starting it a couple days ago and it cranked over but then all of a sudden, it stopped and nothing worked. I also changed the solenoid as a precaution, also because it was original. All battery cables are new with new batteries. Am i getting a short somewhere?

 

[Don S]

Re: Mercruiser 165 key switch wiring?

Where do you have the test leads of your meter too when testing?

You should be testing with the black test lead to a known ground, and the red test lead on different places. Ground always stays on ground unless you are doing a voltage drop test, and I don't think you are wanting to do that.

 

[sledhead26]

Re: Mercruiser 165 key switch wiring?

Yes thats exactly what i have been doing. My black test lead in on the main ground stud for my fuse block which is grounded to my battery. My red lead is the one I'm moving to different spots.

 

[Don S]

Re: Mercruiser 165 key switch wiring?

If you have a 12V test light, hook the clip to your ground and check the B terminal on your switch and see if it lights. I suspect it won't.

 

[sledhead26]

Re: Mercruiser 165 key switch wiring?

You are correct. It doesn't light. But it shows 11.98 volts with my meter. Why is that? Do i have a bad ground?

 

[Don S]

Re: Mercruiser 165 key switch wiring?

Because you have just enough voltage for the meter to read, but not enough to power anything. Loose corroded connection somewhere between the switch and the engine circuit breaker, faulty breaker, even faulty battery cables or loose dirty battery connections.

PS 11.98 volts on a battery is considered dead.

Charge it up and get it load tested if your meter shows that across the battery terminals. If you show 12.3V or higher on the battery itself, then you have wiring problems mentioned above.