What causes a trim gauge to slam to the bottom when turning on the key ?

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deebury

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Help please, Johnson 90hp, '86 model. I'm tidying up old wiring and trying to get the gauges all operational again. I had removed an old wiring harness and remote and fitted a later type OMC one I got from a dismantled 140hp. Everything fell into place nicely, and while rigging the trim gauge just on the floor before fitting into the dash, the gauge was working well and normal, sure as eggs, once fitted and wired, ...no go :blue: When the key is turned on the needle just bottoms out immediately. I've checked, double checked and triple checked the hook up, removed the gauge, tried another, all the same result. Very frustrating. Any ideas anyone ? Thanks in advance....
 
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boobie

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Re: What causes a trim gauge to slam to the bottom when turning on the key ?

What happens if you disconnect the S wire from the gauge and turn on the ign switch ?? What position is your mtr in ??
 
Joe Reeves

Joe Reeves

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Re: What causes a trim gauge to slam to the bottom when turning on the key ?

Although this may not pertain in your case.... the usual mistake one makes when installing that gauge is not having the ground leading to a true ground. If you're picking up a ground from some other component that has voltage applied to it... voltage will be flowing thru that other component and out it's ground terminal (causes weird happenings).
 
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boobie

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Re: What causes a trim gauge to slam to the bottom when turning on the key ?

Joe, did you ever run into any missed matched trim senders and gauges on any OMC product ??
 
Joe Reeves

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Re: What causes a trim gauge to slam to the bottom when turning on the key ?

boobie said:
Joe, did you ever run into any missed matched trim senders and gauges on any OMC product ??
Click to expand...

Boobie.... The only ones I used were the standard OMC gauges, and I never encountered a mismatch regardless of what type OMC sender I used.

Never had a problem excepting one that a fellow who either wired his 12 volt supply off of his PTT switch OR had his gauge ground wired to the black/yellow "M" igniiton switch terminal. I really don't remember exactly how he had it wired (been so long ago) but it really had that gauge doing very weird things.
 
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deebury

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Re: What causes a trim gauge to slam to the bottom when turning on the key ?

ok, Thanks for the info, I think maybe I have a failing sender unit ? I was down the back of the boat with the motor right the way up and was just flicking the little arm up & down with no result, then all of a sudden it flew up and slammed back down again and hasn't moved since. Picking that is probably faulty ? Any thoughts ?
 
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Fed

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Re: What causes a trim gauge to slam to the bottom when turning on the key ?

Test it with an ohm meter.
Fully up 88 Ohms, fully down 1 Ohm.
 
Joe Reeves

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Re: What causes a trim gauge to slam to the bottom when turning on the key ?

deebury said:
ok, Thanks for the info, I think maybe I have a failing sender unit ? I was down the back of the boat with the motor right the way up and was just flicking the little arm up & down with no result, then all of a sudden it flew up and slammed back down again and hasn't moved since. Picking that is probably faulty ? Any thoughts ?
Click to expand...

Strange that the unit functioned properly when you had it assembled on the floor (Post #1). Is this a different sender unit?
 
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deebury

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Re: What causes a trim gauge to slam to the bottom when turning on the key ?

Same sender unit. just assembled on floor = working, mounted into dash = not working. Gremlins in the system ! I'm picking it is the sender unit playing tricks though. With the motor all the way up, toying with the arm on the sender unit, sometimes triggers the gauge, sometimes not. But when it does not it just sends the needle to the bottomed out position. Part is expensive here in NZ so didn't want to splash out if it may not be the problem. Quoted $175 (nz$) ouch !
 
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deebury

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Re: What causes a trim gauge to slam to the bottom when turning on the key ?

Have just checked it again after sitting for a couple of days and you guessed it... working fine. No problems at all. Expect to see those gremlins again next time on the water I expect. Thank you all for your input.
 
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boobie

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Re: What causes a trim gauge to slam to the bottom when turning on the key ?

Sounds like a bad wire connection or faulty trim sender. You really don't need it when under way. Use your "ears". JMHO.
 
Joe Reeves

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Re: What causes a trim gauge to slam to the bottom when turning on the key ?

boobie said:
Sounds like a bad wire connection or faulty trim sender. You really don't need it when under way. Use your "ears". JMHO.
Click to expand...

Just can't resist Boobie..... Which ear should he attach the wires to? :)
 
CaneCutter79

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Re: What causes a trim gauge to slam to the bottom when turning on the key ?

Joe Reeves said:
Just can't resist Boobie..... Which ear should he attach the wires to? :)
Click to expand...
Joe......you're just wrong!! Hahaha!!

Funny you're having a similar issue. My tach gauge (brand new) wasn't working. Had power, everything was wired correctly, etc. I pulled the gauge out several times to test. A few days later, I pull the gauge out to test one last time with motor running and like you said.........it started working no problem. Works great now. Go figure....

Sounds like your sending unit wasnt getting a goo contact or connection. Could always spray a little electrical parts cleaner on the unit? Probably ly sealed and a waste of time but if you could get cleaner on the contact, I bet that might help.

Find a used sender on eBay if it keeps acting up.
No one "needs" a trim gauge. Its eye-candy. They aren't that accurate or reliable. I have one. Heck.....I just installed one! :)
 
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boobie

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Re: What causes a trim gauge to slam to the bottom when turning on the key ?

The only time a trim gauge is any good is if you have a stern drive or an outboard you can't see and you're coming into shallow water. Like I said, when under power use your " ears " and listen to the rpm of the mtr.
 
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deebury

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Re: What causes a trim gauge to slam to the bottom when turning on the key ?

CaneCutter79 said:
Joe......you're just wrong!! Hahaha!!
Could always spray a little electrical parts cleaner on the unit? Probably ly sealed and a waste of time but if you could get cleaner on the contact, I bet that might help.
No one "needs" a trim gauge. Its eye-candy. QUOTE]

Wow CaneCutter79 ! Its like we have an ESP thing going on telepathically ! That's exactly what I have done for the last 2-3 nights is spray electrical cleaner over that part in the vain hope that it may help. I don't know whether or not it has penetrated but what I do know is that I now have a working trim gauge !

Yes possibly I do not "need" a gauge but is does leave one annoyed when its there but not working, also it does give passengers confidence to see you have a well maintained craft when items work. Because i'm sure they'll notice if equipment on your boat is not working. Pretty sure I don't want to see an airline pilot "tapping" gauges before we head down the runway ! And because it's main use is recreational (skiing, wakeboarding, etc) it is a great guide to show new drivers roughly where to trim to, for the most comfortable ride.

Great joke Joe ! :) reminds me of the time I first heard my guitar teacher say he first learned to play by ear. I thought that was waaaaayy out there, I was just happy to learn to play using my fingers !

Thank you all again for your comments, suggestions and tips. End result is my gauge is working. Thank you.
Click to expand...
 
Joe Reeves

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Re: What causes a trim gauge to slam to the bottom when turning on the key ?

deebury said:
Great joke Joe ! :) reminds me of the time I first heard my guitar teacher say he first learned to play by ear. I thought that was waaaaayy out there, I was just happy to learn to play using my fingers!
Click to expand...

That's how I learned to play the guitar also, starting when I was 16 years old. I sold my Fender amplifier some time ago, gave it away really (close friend) for $100... big amp, multiple inputs, vibrato, the works. Since my wife passed away, I thought I'd go back to playing to see what I've forgotten, something to do (still have two guitars)... pretty hard to find another Fender amp cheap.
 
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