122S HORN UPGRADE        R. Kwas, amended 6/2001

So…you’ve installed a high performance alternator in your baby, and are enjoying: white headlights, a heater blower whose whine doesn’t vary up and down with engine RPM (an audio voltmeter!?), and starting with a fully charged battery on Arctic January mornings. Life is pretty good, but your horn’s assertiveness level still reminds of a Yak with emphysema - doubtfully capable of grabbing the attention of that Sensurround listening, cell-phone yapping, Road-Master!? driving, @%??*%/ who seems to be drifting that road-barge into the lane you are already occupying.  For those occasions when its needed, a well working horn is sure nice to have! 

Background The gentleman who designed the 122S electrical system was probably also overly guilty of following the KISS principle, having omitted the cost of installing a horn relay, thereby passing all of the required (high) current through the steering wheel switch (notice I said gentleman, as in singular, because an engineering task force was certainly not necessary for the task of designing a Sixties vehicular electrical system). This poor steering-wheel switch however, is totally overworked, (see also below) and assuming the horns themselves have survived decades of salt attack in front of the radiator, their electrical connections are probably as crusty as those on the Titanic about now! The total effect is a marginal current path, reduced voltage available, therefore poor performance of the horns.  

[added to article 6/2001]  With degradation over time, of the foam separating the two plates which make up the horn switch in a 122, the plates have been known to come together by themselves causing an unwanted activation of the horns.  At best, this merely  causes (humorous) frantic actions on the part of the driver, as he attempts to stop drawing attention to himself in traffic, and at worst, who-knows-what from the driver being surprisingly so loudly distracted!  If the force required to activate the horn is minimal, your vehicle's horn switch is likely fixin' to surprise you...you might want to preempt this with the 122 Horn Switch Repair permanent fix on the Service Notes section. 

Before performing this upgrade, and to make certain that it will remedy anemic horns, the health of horns themselves should be verified by disconnecting their wiring and connecting them directly to battery power using two lengths of temporary test wire (observe polarity, brown is positive on original wiring). If their performance improves noticeably, the vehicle is a good candidate for upgrade. If not, the horns should be replaced first (Fuse 2 current rating should be verified to be adequate for new horns when replacing).

Special equipment required: Relay-PN1234750 typically marked SR803 or similar, wire (16ga,. 600v insulation), assorted crimps, crimping tool, Penetrox or similar anti-corrosive paste.

Note: This procedure has been prepared with the utmost care. It is however strictly a guide to be used in conjunction with normal cautious shop practice. I cannot be responsible for your actions. Work safely!

General The step by step procedure follows. For the purpose of checking as well as adding to your vehicle manuals, or if you are more comfortable working with a wiring diagram than a "word problem", 122S HORN WIRING: BEFORE AFTER diagram also follows.

  1. At Fuse Panel, determine which Fuse 2, brown wire supplies power to horns. To do this, with [Ignition On], pull one brown wire a time and try horn until locating the wire which when pulled causes the horns not to sound. Reconnect all other brown wires leaving the (horn power) wire disconnected.

  2. Tape this wire to prevent its contact to any terminal, and tuck into harness as it will not be used.

  3. With [Ignition Off], prepare with a crimp terminal and connect a new (horn power) wire to the fuse block terminal made free in Step 1, routing the other end to inner fender wall location of new horn relay (mounted with other relays present).

  4. Connect new (horn power) wire to terminal 30/51 of horn relay.

  5. Locate (horn control) wire coming out of steering box, cut this wire at existing butt crimp, installing a new butt crimp and wire, routing this new (horn control) wire to terminal 85 of horn relay. Old crimp and associated (two) black wires should also be taped and tucked away as they will not be used.

  6. Disconnect original (horn control) black wires from both horns, tape and tuck into original sleeving, and after cleaning any corrosion on horn terminals with emery cloth or similar and applying anti-corrosive paste, replace with two new (horn grounding) wires connected to any handy place on vehicle chassis (scrape away paint and also apply anti-corrosive paste at this connection).

  7. Disconnect original (horn supply) brown wires from both horns, tape and tuck into original sleeving, and after cleaning up any corrosion on horn terminals with emery cloth or similar and applying anti-corrosive paste, replace with two new (horn supply) wires routed to horn relay and connected terminal 87.

  8. Double check that all wiring is correct.

  9. With [Ignition ON], verify horn function.

Your comments on and inputs to this procedure are welcomed and appreciated. Ron



Related Threads: 

"No horn operation 444-544 1965"  http://www.brickboard.com/RWD/index.htm?id=813560

"Route of horn wire(s) 120-130"  http://www.brickboard.com/RWD/index.htm?id=813801

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