Upgrading inner fairing

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May 6, 2022 | 12:13 PM

#11

t150vej

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Joined: Dec 2005

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From: NC USA

Quote:

Originally Posted by Idiocracy

You are dead on with wire color, and the double terminal sending unit. So it sounds like you are saying that when there is actual pressure, the gauge should function properly. Power / Ground / signal all come straight from the original harness for the 93, so there is no tie in with all the wiring for the other gauges / radio / speakers.

The power to the oil gauge is orange which is shared power from ACC circuit. It feeds the gauges, brake light switch, turn signal module, neutral and oil light and radio depending on the year model of radio itself. And the grounds are all tied together here and there. The sender post/wire for the gauge is dedicated to just that.

The oil light side of the sender is a simple n/c - grounded with less than 5psi, open above that and goes directly (thru the harness) to the light bulb. I hooked my sender wires up backward once and maybe popped the sender, had to buy one. Another member here did the same and was OK after correcting the wires. So you may have a bad sender, maybe not. Kinda sounds like it if it pegged.

I can't find my notes for the values of the gauge side of the sender, I'll check mine with an ohm meter and post back later.

May 6, 2022 | 01:44 PM

#12

t150vej

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From: NC USA

Sw/off, eng/off, sender wires connected (or not) -
WK post <1 ohm (grounded) It's for the light
G post 10 ohms. It's for the gauge and that value (resistance) increases with engine running as oil pressure rises.

Sw/on, eng/off, wires connected -
WK - .3 volt (grounded)
G - 1.2 volt (floating ground from gauge)

So if you don't get the posted readings for ohms, disconnect the wires at sender and re-check. If the gauge wire (green) is grounded OR open somewhere along the way, the gauge will peg. I'd forgotten that part. Forgot to check voltages sw/on, wires off sender but they will likely both show 12v with a high impedance DVOM, the light wire for sure with any voltmeter.

Last edited by t150vej; May 6, 2022 at 01:47 PM.

May 7, 2022 | 07:02 AM

#13

Idiocracy

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From: Michigan

Thanks for that. I'll check those this morning and let you know.

May 7, 2022 | 08:53 AM

#14

Idiocracy

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Joined: Apr 2020

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From: Michigan

Quote:

Originally Posted by t150vej

My readings are (engine off for all measurements)
Switch off / wire on sender
gr/bk - 13.6 ohms / 0.1 volts
W - 1.0 ohms / 0.1 volts

Switch on / wire on sender
gr/bk - 187.0 ohms / 0.72volts
w - Infintite resistance / 22mV

I think the readings are close enough to call call them good with some variation in there.
The gauge is wired right (its marked for power and signal).
Good continuity through the signal wire, key on and off.
Good ground continuity key on and off.

Maybe the gauge is screwed?

Last edited by Idiocracy; May 7, 2022 at 09:06 AM.

May 7, 2022 | 09:39 AM

#15

Schex

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Joined: Apr 2011

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From: SE Louisiana

Quote:

Originally Posted by Idiocracy

if I unplug the signal wire and put it to ground, the gauge pegs,

Im not ready to fire this thing up yet, (and it would be a long shot) but any chance the ground switches with the bike running?

Take the g/bk off the sender, does it read zero disconnected, and pegged when grounded? If so, the gauge and wiring is working
older oil gauges worked opposite

I tried an oil gauge from a 2012 on a 1990 years ago, it read backwards, pegged with engine not running and would come off the peg and read with engine running,

May 7, 2022 | 10:15 AM

#16

t150vej

HDF Community Team

Joined: Dec 2005

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From: NC USA

Quote:

Originally Posted by Idiocracy

My readings are (engine off for all measurements)
Switch off / wire on sender
gr/bk - 13.6 ohms / 0.1 volts
W - 1.0 ohms / 0.1 volts

Switch on / wire on sender
gr/bk - 187.0 ohms / 0.72volts (1.2 on mine)
w - Infintite resistance / 22mV

I think the readings are close enough to call call them good with some variation in there.
The gauge is wired right (its marked for power and signal).
Good continuity through the signal wire, key on and off.
Good ground continuity key on and off.

Maybe the gauge is screwed?

I read but didn't record ohms w/ sw/on/connected (but will again sometime and record). Seems mine was high in the m Ohm range of reading. Resistance gets wacky across voltage/load and I'm not tech enough to cipher all that.

I tend to agree your sender is good, gauge is bad. The voltage from the gauge to sender looks low but too close to call as a definitive clue.

There are a few on ebay at this moment and for about $20. and a few days wait, I'd replace the gauge. Search 75032-87 and unless you want a brand new one, the one from pinwall in Ohio would be my first choice. I've dealt with them and actually been there years ago. They are very reputable and accurate in descriptions, ship quickly and so on.

Just for the sake of knowledge, before (and after) you swap the gauge, check the green wire voltage disconnected at the sender. I'll check mine and record so we can compare notes again later. Sometimes process of elimination is quicker and easier to get something working, but I still like to learn what little bit I can long lifes road...

May 7, 2022 | 10:18 AM

#17

Ya Tigor

Road Captain

Joined: Aug 2008

Posts: 635

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From: Philadelphia Northeast

Quote:

Originally Posted by Idiocracy

Maybe the gauge is screwed?

Or you've got a Twincam gauge (for example if you bought an instrument set off 1999 bike that still had a cable speedo).
All 91-98 Tourings has the same dual sender 74406-87 on them. So 96-98 gauge should work with your 93 sender with no problem. Twincam sender works backwards so they changed the gauge at 99.

Last edited by Ya Tigor; May 7, 2022 at 10:24 AM.

May 7, 2022 | 10:38 AM

#18

t150vej

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Joined: Dec 2005

Posts: 5,404

Likes: 2,605

From: NC USA

Quote:

Originally Posted by Schex

Take the g/bk off the sender, does it read zero disconnected, and pegged when grounded? If so, the gauge and wiring is working
older oil gauges worked opposite

I tried an oil gauge from a 2012 on a 1990 years ago, it read backwards, pegged with engine not running and would come off the peg and read with engine running,

Yes, these work backward from most electrical pressure gauges.