tachometer problem

I have a 1995 Johnson 200 HP Venom outboard, I'm having a problem with the tachometer, it stopped working, I checked the wiring and there is a connector about a foot from the tach that when i disconnect it I get 12 volts coming from the wiring from the motor but when i plug it in I get only about 7 volts at the connector that plugs into the back of the tach, is this right? is the tach bad? Am I checking it wrong?, any help is appreciated, Thanks

Re: tachometer problem

welcome

is the tach needle on zero?

there are 3 wires going to the tach. one is 12v positive one is 12v negative these are landed at the bolts and may be daisy chained to other gauges. then there is a grey wire which is the tach pulse wire which goes to a smaller post. check the tack for 12v when the key is turned on then with the key turned off look on the back of the tack for a rubber plug and under that should be a screw with numbers around it. remember the number the turn the screw back and forth a few times then turn it back to the original number and test start the engine.
wiring diagrams can be found in the sticky notes at the top of the forum or in the electrical forum sticky notes

Re: tachometer problem

What's the color of the wire you're talking about ?? The gray wire gives the tach it's pulses.

Re: tachometer problem

If your tachometer has four wires.......

Purple = 12v
Gray = Sensor
Black = Ground
Blue = Light bulb

(Testing Tachometer With Water Cooled Regulator/Rectifier)
(J. Reeves)

A quick check is to simply plug in a another new tachometer as a piece of test equipment. If the new tach works properly and the old tach didn't, obviously the old tach is faulty.... but usually boaters don't carry around a spare tach (see below).

A faulty rectifier wouldn't damage the tachometer, the tachometer simply wouldn't work. This is due to the fact that the tachometer operates off of the charging system and the rectifier converts AC voltage to DC voltage, enabling the charging system. A faulty rectifier disables the charging system, and the tachometer simply doesn't register.

However.... those water cooled regulator/rectifiers that are used on the 35 ampere charging systems (and some others) bring into play a different type problem, and as you've probably found out, they are really a pain to troubleshoot via the proper procedure. There's an easier way.

The tachometer sending/receiving setup operates off of the gray wire at the tachometer. That same gray wire exists at the engine wiring harness which is connected to the engine electrical terminal strip. You'll see that there is a gray wire leading from the regulator/rectifier to that terminal strip, and that there is another gray wire attached to it. That other gray wire is the wire leading to the tachometer which is the one you're looking for.

NOTE: For the later models that DO NOT incorporate a wiring terminal strip, splicing into the "Yellow Wire" mentioned will be necessary.

Remove that gray wire that leads to the tachometer. Now, find the two (2) yellow wires leading from the stator to that terminal strip. Hopefully one of them is either yellow/gray or is connected to a yellow/gray wire at the terminal strip. If so, connect the gray wire you removed previously to that yellow/gray terminal. Start the engine and check the tachometers operation, and if the tachometer operates as it should, then the regulator/rectifier is faulty and will require replacing. If the tachometer is still faulty, replace the tachometer.

If neither of the yellow wires from the stator is yellow/gray, and neither is attached to a yellow/gray wire, then attach that gray tachometer wire to either yellow stator wire, then the other yellow wire, checking the tachometer operation on both connections.

I've found this method to be a quick and efficient way of finding out which component is faulty.... the tachometer or the regulator/rectifier. It sounds drawn out but really only takes a very short time to run through. If the water cooled regulator/rectifier proves to be faulty, don't put off replacing it as they have been known to catch on fire with disastrous consequences.

Re: tachometer problem

The needle started at about 5, I tapped on it and it moved to about 3

glenn property of pam said:

welcome

is the tach needle on zero?

there are 3 wires going to the tach. one is 12v positive one is 12v negative these are landed at the bolts and may be daisy chained to other gauges. then there is a grey wire which is the tach pulse wire which goes to a smaller post. check the tack for 12v when the key is turned on then with the key turned off look on the back of the tack for a rubber plug and under that should be a screw with numbers around it. remember the number the turn the screw back and forth a few times then turn it back to the original number and test start the engine.
wiring diagrams can be found in the sticky notes at the top of the forum or in the electrical forum sticky notes

Click to expand...

The needle was stuck at about 5, I tapped on it a couple times and it moved down to about 3

Re: tachometer problem

boobie said:

What's the color of the wire you're talking about ?? The gray wire gives the tach it's pulses.

Click to expand...

There is gray, black, purple, in one connector, and a separate white wire

Re: tachometer problem

Arty76 said:

The needle started at about 5, I tapped on it and it moved to about 3






The needle was stuck at about 5, I tapped on it a couple times and it moved down to about 3

Click to expand...

3 what .....300 or 3000. If you have voltage between the purple and black with the key turned on then it should be zero or the tack is bad.

Re: tachometer problem

So I put a wire on the ground terminal and a wire on the 12+ volt terminal and touched them to a battery and the needle went to zero, does this mean the tach is ok? Just not getting 12 volts to it for some reason?