Tachometer problem on my yamaha 175 2stroke outboard

[Claus Andersen]

Yamaha log in

Hi

I have a Tachometer problem on my yamaha 175 2stroke outboard

It Will no show the RPM. At all time. I Think there is a loose connection somewere ?

I tryde with a new wire from the control / Throttle Unit 3wires -cause some time the tachometer Will show RPMs When I touche the wires - but with no luck.

I need a diagram with the actuator the on the Enging, and some advise ?

175DETO
6G5
L
350407
R

Clausnuuk@hotmail.com

Ty..
Claus.

[Sequoiha]

coming out of the main harness from the engine to the keyswitch are three little wires, that need to be connected to the tach,, yellow, black, and green, then the tach will work, unless it is a bad tach, also on the back of the tach is a light, the bright blue wire hooked to a B+ or Yellow key on power will turn it on..

[Claus Andersen]

I have a Tachometer problem on my yamaha 175 2stroke outboard

That is the Three wires i just been changing -with no luck-

? On the back of tachometer, Bright blue wire hooked to B+ ( is that just too +?)
The yellow in connected to +
The meter is ON but shows "0"?

Can i have a diagram, i know How to read it. Ty.

Just tell me where i Can read voltage or bee reading ohms on witch places.

[Sequoiha]

the gauge has 4 main wires, Yellow= switched B+ or key on power, Black= ground, bright blue is a light wire, can be hooked to yellow or nav lights, and Green, the tach lead, there are other wires for the oil and over heat.

[rodbolt17]

I am assuming your engine is a non US market model.

over the years Yamaha switched from a stator driven signal taken off the rectifier to a CDI generated signal based on a pulser coil signal.
there are two green wires in the 10 pin main ign harness.
light green,trim down and dark green tach signal.

if using the 703 sidemount control box you will have 4 wires in a bundle green,black, red and yellow.
that dark green is tach send and can be tested with a voltmeter.
if your meter has a Hz function use it,if not use a DC volt setting.
start the engine with water supplied.
vary the RPM and the meter readings should change as well.

I have no information on non US market engines.

[robert graham]

I've had that same problem and it turned out to be a tiny bit of corrosion inside the in-line fuse holder for the tachometer...seems the humid marine environment can cause this....I check, clean and grease these fuses now and it helps a good bit. Those connection wires on the back of the tachometer can do the same thing....good luck!

[throrope]

Isearched the world over and found 95% of tach problems are caused by bad connections. Since these are the easiest to fix, I suggest starting with each and every one.

[Claus Andersen]

Tachometer problem on my yamaha 175 2stroke outboard

I been tjecking every connection with tachometer (and a new cable) from controlbox to meter.

When the Engine gets in operation temp. / After 10-15min.
The tachometer Works "better"

? Where on/in the enging is the sensor that measure the RPMs ?

I been cleaning the crank pos. Sensor ? Black One next to the rotor assy with 2 green wires, there was a little rust. And running engine after, and the tachometer jumped in RPM 4- 12- 33 And worked periodical better !?

?
I need to know the diagram from RPM sensor in the engine to the tachometer.
?

[Claus Andersen]

I been tjecking every connection with tachometer (and a new cable) from controlbox to meter.

When the Engine gets in operation temp. / After 10-15min.
The tachometer Works "better"

? Where on/in the enging is the sensor that measure the RPMs ?

I been cleaning the crank pos. Sensor ? Black One next to the rotor assy with 2 green wires, there was a little rust. And running engine after, and the tachometer jumped in RPM 4- 12- 33 And worked periodical better !?

?
I need to know the diagram from RPM sensor in the engine to the tachometer.
?

[rodbolt17]

tach signal on that engine is generated by the CDI based on pulser coil signal inputs.
find the bad connection.
crank position sensor generates the spark for cylinders 2 and 5.
nothing to do with tach send.

[Claus Andersen]

Hi rodbold17


Tach signal on that engine is generated by the CDI based on pulser coil signal inputs. find the bad connection.

! I been loooking at All connections - i Think so - !

crank position sensor generates the spark for cylinders 2 and 5.
nothing to do with tach send.
! CPS in Not the One that is sending til RPM?
That is what i been told earlier..

I need to know the diagram from RPM sensor in the engine to the tachometer.

??

[boscoe99]

In the ten pin main engine harness that runs from the motor to the helm is a green wire. That wire transmits the tachometer signal.

There are three main wires required for the tachometer to work. Yellow for positive key on 12 volt power. Black for ground. Green for the tachometer signal.

As noted, check the wire for frequency or a voltage change as the speed of the motor is changed if you suspect the signal is no good. Perhaps some wiring is compromised between the motor and the tachometer. Check all of the connections. It is a good idea sometimes to disconnect and reconnect the connectors several times to try and scrub off any corrosion that might have built up between the pins and their sockets, within the connectors.

In most/all remote con*****ed Yams there is a small harness used to get power, ground and the tachometer signal to the tachometer from either a standalone key switch panel or a 701/703 control box.

Here is the best diagram I could find that might be applicable to your motor:

[Claus Andersen]

TY. boscoe99

I just been mesuering on the green wire beheind thacometer 9volt in ideal RPM. And rising With throttel OK. But there is still 0 RPM on thacometer ?
I have Checkede all of the connections !?
And tryed with another thacometer + I been tjecking every connection with tachometer (and a new cable) from controlbox /remote control to meter...?!

I been mesuering 2volt on the To green wires in ideal, from the CPS crank position sensor.
What is mesuering the RPM in the engine a sensor ?

[boscoe99]

The tachometer indicates engine speed by receiving pulses directly from either the lighting coil or from a CDI or ECU.

In the case of your motor I believe it is from the CDI.

If you got a service manual you might be able to track the tachometer signal from the dash all the way back to the CDI.

[Claus Andersen]

Hi boscoe99

On my engine the RPM signal comes from the green wire on the 10 pin from the CDI.
I been Reading this service manual.
http://www.yamaha-motor.com/assets/s...-03-64_745.pdf

With very little help.. ( just Info. Notning with troubleshooting tachometer)

My question still is ?
What is mesuering the RPM on the engine a sensor ?
I need some measurement points to measure voltages, from the RPM sensor (?) to the green wire behind the tachometer ?