Alternator Question - Help please

[Swampmouse]

I just got a new tachometer for my boat. On the back there is a selector switch and the instructions say set to 1/2 the number of poles on the alternator.

Can anyone please tell me how many poles are on a 1983 Johnson 115hp?

Currently the new tach is not registering anything which leads me to believe I have the switch in the wrong position OR the wiring is not grounded good(Maybe the grounding is why the old one is not working???)

Thanks,
SM

 

[ezeke]

Re: Alternator Question - Help please

Set the switch to 6 or 6p.

The black ground and purple positive wires should come from the ignition switch. The grey sender wire should come from the main harness.

Check the gray wire for continuity with your ohmmeter and absolutely no voltage.

If you want light, you will want the blue wire connected.

 

[Swampmouse]

Re: Alternator Question - Help please

Thanks EZEKE!!

 

[Swampmouse]

Re: Alternator Question - Help please

Ok I checken my wires.

On my OLD tech, I had only 3 posts /wires. Black ground, blue going to the light and a purple sending wire - or at least thats they way it was. The tach never worked since I have had it.

My NEW tach is a 4 post version. If I read the instruction diagram correctly I run a jumper wire from the ignition post to the light post.

I have no gray wire - only black, blue, and purple.

Does this make sense, or am I missing a wire?

Thanks,
Sm

 

[Swampmouse]

Re: Alternator Question - Help please

It appears that I have no juice coming in from my blue wire.

COuld I simply run a hot wire from my positive terminal of my fuse box to the tach?

SM

 

[Silvertip]

Re: Alternator Question - Help please

No -- because the tach would have 12V on it all the time and run down the battery. You need to get the power problem resolved. The 12V wire doesn't have to come from the switch. If you have a gas gauge, does it work? If it does, connect to the +12V and ground terminals on that gauge. The light can connect to the light post on any of the other gauges. If you jumper it to the +12V post the light will be on anytime the ignition is on.

 

[Swampmouse]

Re: Alternator Question - Help please

I am at a loss now. I got power - 12.4 volts or some thing like that. I got a ground.

I ran a new sending wire wire directly from back of tach to post 1 (yellow) and also tried post 2 (also yellow wires) on the wiring harness thing on the side of the motor and still no working tach???!!! Is this a problem to do it this way?

Any new suggestions now? I really need to get this tach working so I can do a link & sync to set the timing and REALLY REALLY need to go fishing soon!!!!


Thanks,
SM

 

[ezeke]

Re: Alternator Question - Help please

What kind of remote control do you have? If it is a side mount, it has a plug for a tach.

I am fairly familiar with most brands of tachometer, so what do you have?

All recent conventionally wired OMC/BRP systems have a gray wire leading from the engines terminal block. That gray wire is the sender wire for the signal that drives the tachometer. Ya gotta have it!

The sender will be useless if your rectifier/regulator is no good, which is often why tachometers don't work.

If you are not getting a charge on your battery, you won't get a signal to your tach either.

 

[F_R]

Re: Alternator Question - Help please

Agreed, check your alternator output. If the alternator isn't working, the tach won't either.

 

[Swampmouse]

Re: Alternator Question - Help please

Thanks guys. I have a Teleflex tachometer. I will check tomorrow or Monday for the gray wire coming off the engine.

At some point, somebody got a hold of the wiring under the console of this boats and massacred it, so it would not surprise me if the gray wire was actually white or some other color by the time it gets to the console.

Again, I want this to work so i can set the timing. Is is possible to set the timing without a working tach. I have spent so much money rebuilding this motor that I really do not have the extra money right now to replace anything else if altenator or rectifier is bad.

Thanks for all the input. I will recheck wiring and let you know what I find.

SM

 

[HighTrim]

Re: Alternator Question - Help please

"http://ww2.tflx.com/pdf/obtach~1.pdf"

 

[ezeke]

Re: Alternator Question - Help please

Just so it does not get too confusing, blue is the customary color for the positive lighting wire which usally come off of a light switch. Most people have a light switch for running lights and another light switch for the panel or gauges. Most boats have all the gauge lights wired in series.

For safety reasons, I have my gas gauges wired separate from everything else.

I have never seen a lighting system wired directly to an ignition switch with no other switch between the ignition switch and the lights, but I guess I have not been out much.

Here is a link to a good bit of information on the control wiring, including a diagram at the end which shows the tachometer plug and wiring:
"http://continuouswave.com/whaler/reference/ignitionSwitch.html"

 

[Swampmouse]

Re: Alternator Question - Help please

Thanks guys. As I am in the process of getting ready to move and bad weather this week, I have not been able to get outside and tinker around. I will check out the links and also look for the gray wire coming off the engine.

Rectifier/regulator may be the cause, but again looks like more checks and tests.

Thanks again,
Sm