wiring question 1987 yamaha 70 hp

[medicineman]

I just purchased a yamaha 70 hp 1987 2 stroke that was originally installed on a bass tracker boat. The wiring was all cut loose before i bought the boat. It did come with the control handle and the 10 wire main cord is obvious how it reconnects. there are three other groups of wires that go into the engine. one group of four works the tilt/trim, one group might have something to do with the warning buzzers, and i am wondering if the other group of purple, black, orange, and white might possible be another remote start wiring harness. the motor will crank and run with only the main harness wired back together, but i would really appreciate knowing for sure which of these other wire sets i can remove without problems. this is a precision blend engine and i don't know if some of this wiring is required to be hooked up so i would be warned of oiling issues or if the engine itself has a built in warning system. i am planning on installing this engine on a pontoon. thanks in advance for any knowledge shared!

[dray0151]

If you can provide the entire model number and maybe serial number I think probably Boscoe when he comes on and sees your question will be able to help with some diagrams. Also you might look at the link below for a manual of your engine that may contain some diagrams.

https://www.vansoutboardparts.com/se...a-shop-manuals

[pstephens46]

Wonder why all the wiring was chopped?

[medicineman]

70 ETLH serial # 463410 as to why chopped off, i was told boat and engine had not been used for a few years and prior owner was more concerned with reusing boat than engine.

[boscoe99]

Is this what you are looking for? This is for a circa 2000 70 HP motor. Yamaha changed some connectors from round to square circa 1994.

[boscoe99]

The warning horn is built into the 703 control box. Or in a switch panel if a top mount 704 control box is used.

Only the ten pin harness from the motor to the control box is required. Gauges are options. Need to know what type of gauge you intend to use.

[99yam40]

Wonder why all the wiring was chopped?

thieves tend to do that kind of stuff
but who would want a 87 motor now a days
way too old

[medicineman]

this could be the information i seek. mine has three groups of wires along with the main wiring harness. i know the engine was on a bass tracker originally. i know one set of wires will operate the trim and i have traced one set to the oil tank thus i am guessing it has to do with alarms. i have not been able figue out the third set which has 4 wires inside an insulated wire-----colors are purple, black, orange and white. this particular set was not cut, but rather unplugged from somewhere on the boat-----possibly the console, and has a square white plug with 4 female bullet style plug. i am unsure why one of the other sets works the tilt trim as the tilt trim on 704 remote works without it being hooked up due to the main harness feeding it. Is it possible the bass tracker had another wiring harness to operate the tilt trim from a separate location on the boat? And this motor was not stolen.....i removed it myself from the boat as the current owner had cut wires before i came to get engine. the steering cable and throttle cables were all rusted and frozen up so he had just cut everything loose. by the way, the set that operates tilt trim has one red and three black wires. if i touch the red wire to 12 volt trim motor activates.

[medicineman]

The warning horn is built into the 703 control box. Or in a switch panel if a top mount 704 control box is used.

Only the ten pin harness from the motor to the control box is required. Gauges are options. Need to know what type of gauge you intend to use.

this is not a top mount remote, so it sounds like i would be safe from what you say just disconnecting all other leads.

[boscoe99]

The trim and tilt are con*****ed by the 703 control box. The trim switch is in the throttle handle. The 703 control box also has three wire leads (red/blue/green) for an optional trim switch that is usually mounted at the bow.

The oil status lights and the over temperature light (if installed) are con*****ed by two separate harnesses. Confusing as I know it is going to be, here are some diagrams that show how the motor might have been rigged coming out of the factory way back when. Sorry for the cutting and pasting. Best I have.

[medicineman]

boscoe you have gone above and beyond to help this rookie. many, many thanks.