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Re: TR4A horn relay wiring question

To: walker@hprpcd.rose.hp.com
Subject: Re: TR4A horn relay wiring question
From: pwv@tc.fluke.COM (Pat Vilbrandt)
Date: Wed, 11 Dec 91 14:26:38 PST
> From inside the engine compartment, looking forward, the relay has
> the following spade connectors:
> 
>     +------------------------------+
>     |  ___                         |   (the two on the right are tied
>     |                        ___   |    together)
>     |                        ___   |
>     |             ___              |
>     +------------------------------+
Terminal: 1          2         3&4

You got'cher DMM?  OK.  The relay coil will be the couple hundred ohm
resistance between two of the terminals; the terminal for the relay contacts
will be the "other" terminal (counting 3&4 together as a single terminal).

> The availible wires are:
>                   purple w/yellow stripe (power to the horns)
>                   purple w/black (maybe dk. blue) stripe (from horn button)
>                   purple (power)

Now, assuming that you find the relay coil to be either between terminals 1
and 3&4, or between terminals 2 and 3&4, my *guess* would be:  purple to 
terminal 3 or 4; purple/black to relay coil terminal found above; purple/
yellow to remaining terminal.  (Remember: this is only a guess!!  Proceed
with caution!!  I would proceed by *only* connecting the power and horn
leads; then push the horn button and listen for the click-clack of the relay.
IF and only IF this works, connect the horn lead.  If it doesn't work,
ingore this and everything else I've ever said!)

> I also forgot to label the terminals on the horns, do they care which 
> terminal is power and ground?

Got me hangin.  Again, with your trusty, dusty, DMM, see if there is any
resistance from either of the terminals to the horn or car body.  If so,
the horns are probably polarity sensitive; if not they might not be 
polarity sensitive.  (Damn!  With all these weasel works, I should have 
been a lawyer! ... Naaaaaaa!)  If there is continuity from the terminals to
the body, then you might try to connect the one with the least amount of 
resistance to "earth."

Good luck!

   Pat Vilbrandt       John Fluke Mfg. Co., Inc.        Everett, Washington USA
UUCP: pwv@tc.fluke.COM  or: { uunet, uw-beaver, sun, microsoft }!fluke!pwv
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