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Overheat warning horn light in dash

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soccerrj88

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"1998 225 'Rude. The other

"1998 225 'Rude. The other day the motor seemed to be overheating but the guage never went off in the dash, so I checked it today according to the book, by grounding one of the two tan wires hooked to sensors in the heads. They both turned the light on in the tach, but neither set the horn off. But when the system does a check at first start, the lights all come on, and the horn works good for that so I know it's functional. The VRO system was unhooked by previous owner... not sure if that effects it. Naturally that plug in is disconnected at the motor... thats why I did the check."
 
"I have the EXACT same problem

"I have the EXACT same problem. 1996 MWS Systems Check Tach, 1996 200 HP.
This has stumped the BRP regional service rep, my local dealer service guy, and me.
We have swapped in new harness, three new tachs, different horns...nothing works.
JWB...you say "newer ones". Are you referring to all engines newer than 1996? That's when MWS came out."
 
I thought that was introduced

I thought that was introduced together with the first E-Tech engines?
Check production date on the white sticker on the horns.
 
"WOW. That is very very good

"WOW. That is very very good to know.

I have fought this, measured voltages, measured resistances...everything you could think of.
The shop swapped new parts in, they called BRP rep...no one knew.
Do you guys know that part..."horn driver" (plugs in where the tach would)...used instead of the tach when no tach is present on the rig...that part sounds the horn when engine not running.

Anyway...thanks JWB for the insight. I will go down and do my testing with the engine running to make sure the warning horns work.
Thanks again."
 
"i am aware of the horn driver

"i am aware of the horn driver,...but dont understand the question....it simply replaces the sys ck tach,or sys ck gauge only (no tach)"
 
"here is another,explaing same

"here is another,explaing same thing
---->SEAHORSE
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Birmingham AL

Re: Rusty or seahorse - System Check/Warning Horn Failure (TNBassKisser) » 8:06 PM 4/19/2005 Reply Edit

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You cannot just ground the horn with the key on with a System Check guage.
The engine must be running to test the horn. If the motor is not running, only the appropriate light will illuminate if you ground out a sensor.

The electronics that "drive" the horn are in the 4 light gauge or tachometer, so substitution is the quickest troubleshooting technique. Beg, borrow, or steal a gauge or a horn to find out which is the culprit."
 
"JWB,

MWS = Modular Wiring

"JWB,

MWS = Modular Wiring System. I see it in the books that way for what they also called the Systems Check wiring.

I was trying to post real fast regarding the horn driver module.

Here it is: when trying to debug the horn problem (exactly as described in the very first post above) the engine tech that I have great faith in swapped in one of those horn drivers instead of using the tach. The horn sounded when any tan sensor wire on the engine was grounded during testing, with the engine off. But swapping back in the tach, as well as THREE new tachs...(don't ask me why they thought three would solve the problem), and the horn would remain silent while grounding the same tan wires. As above, the correct associated light would light up in the tach, but no horn. We never tried it while engine running.

I will do that tomorrow, and report back.

Now to be completely accurate...the above quoted post is mostly right ,but also wrong.
Two wires go to the horn. Purple, which is switched +12v and the tan/purple wire which activates the horn when the electronics inside the tach switch that line to ground. You can definitely ground that tan/purple wire and the horn will sound. I have done it many times during this testing.
And of course, if you ground the purple wire, you will blow the fuse at the engine. Never do that.

I had no clue that the engine must be running to make it work right while using the tach in the system.

Let ya know tomorrow."
 
"OK JWB...

You nailed it ag

"OK JWB...

You nailed it again. When the engine is off, the horn does NOT sound when grounding the tan sensor wires at the engine. The lights in the tach operate properly, but no horn.
When the engine is started, the horn works properly when grounding the same sensor wires.

Also, I went back to the book (factory service manual), and on page 7-36, it states "NOTE The warning horn will not sound while in the diagnostic mode."

Diagnostic mode being key on, engine not running.

Thanks very much for the key to fixing this for me...and I hope Randy Moore finds the same thing with his problem. Randy, please post what you find."
 
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