Tach Gauge--Time To Replace?

[Jason2tpa]

Hey boys. I've previously posted about my malfunctioning tach gauge. Made the suggested checks. Got it functioning, then it would crap out again. The short and sweet of what i'm seeing now is nothing. When I start engine I can barely see numbers. After a few minutes of running engine the screen is blank, yet the back light does work. Of course I'd rather replace wiring versus buying a new tach, but I've hit a wall finding a short, if there is one. It's the older version tach and I bought the boat used, so for all I know the tach could be as old as the engine ('98). So maybe it's just time to replace. Your thoughts.

And another issue I'll include because it's probably related to above is the alarm. When starting the engine for the 1st time of the day, and ONLY on the 1st crank of the day, about 75% of the time the alarm will sound. The alarm will actually sound when turning the key to the "ON" position, before turning engine over. I'll start engine and the alarm will continue for 10-15 seconds then stop. During this time the engine continues to run. I can't tell you what the tach screen is indicating (see above) as to why it's alarming.

So, I assume the above 2 issues are related, though not certain. I'm lost as to why the alarm will sound when the key is in the "ON" position, before the engine is even turned over. Though if the issue is with the tach being fouled, maybe that's why. Let's hear it guys. Thanks.

[boscoe99]

What model motor?

Have you tried powering the tachometer directly to a known good voltage and ground source to see what is to be seen?

Low voltage could make the tachometer screen go dim or unreadable.

Low voltage can sound the alarm in some models. Once the motor starts the voltage will rise. Maybe this is why your alarm ceases to sound shortly after start up.

Check all electrical connections from the battery to the motor. Also up at the tachometer.

[Jason2tpa]

What model motor?

Have you tried powering the tachometer directly to a known good voltage and ground source to see what is to be seen?.

Hey bossman. '98 S115TLRW. I have not tried this, no. But great idea. Could you walk me through the steps, more details the better. About a month ago I got under console, disconnected everything, cleaned up the connections, reinstalled. Tach worked perfectly for 2 days. Then went back to crapping out.

[throrope]

More than 9 of 10 times tach problems are bad connections.

I near returned a gps before finding the main fuse for the console located in an inline holder at the stern was corroded. The extra resistance was enough to drop the voltage below instrument tolerance.

I suggest you pull apart, clean and grease every connection starting at the hot side of the battery to the gauge and back to the ground side of the battery.

[boscoe99]

Hey bossman. '98 S115TLRW. I have not tried this, no. But great idea. Could you walk me through the steps, more details the better. About a month ago I got under console, disconnected everything, cleaned up the connections, reinstalled. Tach worked perfectly for 2 days. Then went back to crapping out.

This leads me to believe you have a connectivity problem.


The tachometer should have a bunch of single wires with bullet connectors on the end. Find the yellow wire and the black wire. 12 volts to the yellow wire and battery ground to the black wire. What happens when you connect a battery directly to the tachometer?

Here is an illustration of a typical wiring arrangement for a Yamaha. Check any and all connection points.

[bajakeith]

boscoe99

Damn fine work with your schematic's... KUDO's.. Yes a VOLTAGE DROP test is the first place to start,, next to a disconnected connector !!

[Jason2tpa]

This leads me to believe you have a connectivity problem.


The tachometer should have a bunch of single wires with bullet connectors on the end. Find the yellow wire and the black wire. 12 volts to the yellow wire and battery ground to the black wire. What happens when you connect a battery directly to the tachometer?

Here is an illustration of a typical wiring arrangement for a Yamaha. Check any and all connection points.

Sounds easy enough. Since there will be no switch in btwn battery and tach, i assume once connected the screen should light up. What should i see on the screen? 0?

[Jason2tpa]

I near returned a gps before finding the main fuse for the console located in an inline holder at the stern was corroded. The extra resistance was enough to drop the voltage below instrument tolerance.

I suggest you pull apart, clean and grease every connection starting at the hot side of the battery to the gauge and back to the ground side of the battery.

Will do, thanks!

[bajakeith]

Waterproofing

I'm The only guy in my area that waterproof's all connects,, Most I do with OMC Triple Guard Grease....F-ing amazing stuff and brushes off salt water...Forget the D-electric crap !!

[Jason2tpa]

Update-

In the boat now. When I connect jumper wires between battery -/+ and the tach black/yellow wires the screen has an arrow blinking back and forth over the temp and low oil signs while also blinking "E". What should I be seeing?

Also, the battery tested 12.77v, which is low. Would this be the cause of tach?

[Jason2tpa]

Actually no, what was I thinking. 12.77v is full charge. But same question applies to previous post: when I directly connect tach to battery what should read on the tach?

Also, when tach is connected directly to battery AND i turn key to "ON", the blinking stops. There is an arrow over both temp and low oil and 8 on screen. Important to note that even with the backlight on the arrows and number are faint. Not bold black.

[TownsendsFJR1300]

Are you disconnecting the entire tach and just applying voltage and ground to the tach for your test?


Jason, I was trying to PM you but you have it turned off.


Baha, I also have / use the OMC Triple guard grease (also good for mid section bushing).

Is there ANY issues with it carrying current between adjacent contacts?? (IE, is it conductive?)

I've used dielectric grease for years and have not had to do any "do-overs" from failure. Doesn't take much either..

[Jason2tpa]

When I connected directly to battery the 2 tach harness were plugged in. Should they be disconnected? If so, what should the screen read?

Not sure why you couldn't send me private msg. I have it enabled.

[Jason2tpa]

I may very well be wrong, but with just the power applied, you shouldn't get the blinking lights, alarm, etc.

Just trying to ascertain if the LED unit itself is working or is toast.

Just tried sending another PM, don't work.. You may want to contact admin
and report the issue..

Ok. Once i can get out to the boat ill disconnect the 2 tach harnesses at the tach and see what results, thks.

[Jason2tpa]

Update-

Disconnected the 2 tach harnesses and hooked tach directly to battery. Result: nothing. No numbers, no backlight, nothing. So because of this, safe to say this is a tach problem, not a wiring problem?