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Discussion Starter · #1 ·
Hello, this is my first thread on this forum - I own a 1984 Rabbit and have cared for the car for the past 26 years. Recently, an odd symptom has developed: every time I honk the horn, even briefly, the car ignition seems to "dampen" or hiccup, like the engine isn't getting enough fuel. I re-ground the horn, and this helped initially. But now this very odd symptom has returned. Before getting under the car again to replace the ground, has any one ever experienced such a strange "cause and effect," where merely honking the horn will cause the car to almost stall (at idle) or retard or starve the engine at speed?

I appreciate any one who may read this and may have some helpful advice. Thank you.
 

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Replace the horn, it's drawing too much current. I get a momentary drop in RPMs when I turn
on my Hi-beams, and they're HID...
 

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Replace the horn, it's drawing too much current. I get a momentary drop in RPMs when I turn
on my Hi-beams, and they're HID...
Yes/No.

The issue is that VW grounds the horn via the Horn Relay, and have a 12V positive applied to them all the time.

Issues with flaky power is that the Horn, and the Engine are depending on good outputs and inputs.

What is the Voltage on your Battery when running, should be in the 13-14V range.

I would start with Cleaning all the connections on your 12V positive side of the battery.
Starter, starter solenoid, Alternator, and Battery....

I would then replace the main ground from the Battery to the Frame, and the Frame to the engine. You can use two off the shelf cables to make the repair, or you can buy a one piece cable with the center Lug. Clean the Ground stud at the frame horn. When returning the cable to the stud, make sure that you have a washer at each side and between the "2" piece off the shelf cables, it would hurt on off the shelf cables to Smack them flat on the ends as well as making sure they are flat, I have had to file a few. Then after getting them tight you need to spray them with battery protector paint, don't bother with one shot kinds as the bigger spray is better.

Clean all ground connections you can as well as adding a ground from the Alternator Case Bolt to the engine, I used the Bracket bolt and a ring connector.

You can also add a new ground from the Start cluster on the inside firewall, or the Frame to the Steering shaft outer cover as well as from the Frame to the Steering Gear box inside the engine compartment, as that is where the Ground for the horns is actually.

Dipping voltages is a Connection or ground issue, as well as power cables, and possibly a bad alternator that is putting out the right voltage, but the wrong current. Engines when running actually don't usually require more than 10Amps of current, and it is the Accessories that are the Current hog ie: Lights, A/C, heater blower motors and such.... Diesels use less.

The alternators also come in various outputs, the OEM for a Diesel was 60amp, but there are upgrades from 60, to 65, up to 120. A good automotive electric shop can rebuild them.

Before you go "Changing" things investigate, see if you have a voltage drop between the Battery and frame or alternator.... Determining when and where your issue is, is a biggie...

One of the Bettery things that you can do, whether you have a newer Car, or an older one, is to off load the current of the ignition switch with the use of relays, as in Relaying your headlights, and Starter Solenoid, as that takes the Hi-Current things off the Ignition switch as well as your Headlight switch and gives you longer life of both. (I have a faq in the Cabby section page 3 post 75 that links to your headlights, and well since I rock automatics, a ford starter relay gives your starter more Kick...and off loads the 20-30A off the ignition switch at start, you shorten the wire route to the Headlights, and or starter so they run better, and light brighter, on the head lights I have seen as much as a 2V increase at the Lamps.
 

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Discussion Starter · #4 ·
Thanks Briano1234 - a very detailed observation - I've relayed my headlights before so think I'll do this with the horn (of all things). I've also reground the engine with an over-engineered strap to cure the infamous Mk1 grounding problems known from the past. I sent an earlier reply to everyone, but evidently it did not post. I hope this one does - still getting acquainted with this forum. Final observation for now: very much appreciate this community existing. Back in the day, I saw Rabbits everywhere and a whole corps of mechanics could work on them. Now, guys in their late 60s or 70s are the only fellows who know anything about the cars and their CIS system. Thanks for your quick feedback. I hope to be involved in other threads in the future.
 

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Typical VW horn setup.



Chris's pages are for a westy.

And leave it to the "Mericans" to reverse engineer it backwards from the OEM Golf.



2 fuses, f27, and f3
 

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Discussion Starter · #6 ·
Heck, maybe the relay is "bad" - could it be that simple? Thanks for all the suggestions Briano1234
 

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Discussion Starter · #7 ·
update on my mundane but weird symptoms: I put in a larger gauge copper wire ground and sanded the frame of the car to bare metal where the ground screws in. Cured my very strange idle hiccup when the horn was honked. I've had the car for nearly 3 decades and never encountered such a ghostly oddity. Anyway, for now, it seems to be cured. Just waiting for the next full moon i suppose. Again, thanks for all your observations. Your suggestions were sorely appreciated.
 

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Thanks for the update.
 
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