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kinggeorge13 Samba Member
Joined: May 24, 2013 Posts: 95 Location: Fort Langley, BC, Canada
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Posted: Fri Jul 31, 2020 10:56 pm Post subject: Hot wiring and I apply +12v battery to + on coil the horn beeps? |
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Been working on my 1974 original engine, original dual solex carbs. I don't always have a helper to sit in the front and crank the engine while I work on stuff to get it set up. Meanwhile, I've cranked it over with the ignition key plenty of times and everything is going as I would expect (except not running nice yet and hard starting).
So I build a simple hotwire box so I can do it all from behind the bus. It hooks up to the battery positive and negative terminals. It has two simple switches. A toggle switch to provide 12v to the coil and a heavy-duty momentary push button switch to provide 12v to the spade terminal on the starter solenoid. The LEDs simply let me know my toggle and pushbutton are putting out 12v as expected. I have a fuse in the main +12v wire from the battery to the hotwire box.
However, when I turned on the toggle switch to provide +12v to the coil, my horn activates. What super-simple concept is eluding me? Yes, the push button for the starter solenoid works fine and the engine turns over. Yes, the toggle switch is providing 12v to the coil.
Weird and very unexpected. The horn was not activating when starting from the drivers seat with the key.
_________________ 1975 Westy, Serenity w/FI
1975 Westy, Jack Sparrow w/FI
1979 Kombi, Pistachio w/FI
1979 Kombi, Oliver wFI
1977 Tin top camper, Cosmos w/FI
1974 Westy, Garfield w/ Dual Solex PDSIT
1973 Tin top camper, Bart
1974 gutted Dorper Casper w/ Dual Solex PDSIT
1975 Westy, Stella w/single progressive Weber
1979 Super Beetle, Penelope w/FI
1967 Fastback, Green Hornet w/dual Solex |
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aeromech Samba Member
Joined: January 24, 2006 Posts: 16961 Location: San Diego, California
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Posted: Sat Aug 01, 2020 3:35 am Post subject: Re: Hot wiring and I apply +12v battery to + on coil the horn beeps? |
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That’s quite a list of cars you have in your signature line. Could your hotwiring skills have anything to do with that? _________________ Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound |
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Abscate Samba Member
Joined: October 05, 2014 Posts: 22648 Location: NYC/Upstate/ROW
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Posted: Sat Aug 01, 2020 3:38 am Post subject: Re: Hot wiring and I apply +12v battery to + on coil the horn beeps? |
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I’m guessing your horn wiring is not stock _________________ .ssS! |
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kinggeorge13 Samba Member
Joined: May 24, 2013 Posts: 95 Location: Fort Langley, BC, Canada
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Posted: Sat Aug 01, 2020 6:14 am Post subject: Re: Hot wiring and I apply +12v battery to + on coil the horn beeps? |
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aeromech wrote: |
That’s quite a list of cars you have in your signature line. Could your hotwiring skills have anything to do with that? |
Apparently not. I'm guessing that guys who hotwire VW buses in the middle of the night to steal them don't want the horn going off instead of the engine starting. _________________ 1975 Westy, Serenity w/FI
1975 Westy, Jack Sparrow w/FI
1979 Kombi, Pistachio w/FI
1979 Kombi, Oliver wFI
1977 Tin top camper, Cosmos w/FI
1974 Westy, Garfield w/ Dual Solex PDSIT
1973 Tin top camper, Bart
1974 gutted Dorper Casper w/ Dual Solex PDSIT
1975 Westy, Stella w/single progressive Weber
1979 Super Beetle, Penelope w/FI
1967 Fastback, Green Hornet w/dual Solex |
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kinggeorge13 Samba Member
Joined: May 24, 2013 Posts: 95 Location: Fort Langley, BC, Canada
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Posted: Sat Aug 01, 2020 6:32 am Post subject: Re: Hot wiring and I apply +12v battery to + on coil the horn beeps? |
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A couple other things to mention.
1. There are two spade terminals coming off the starter solenoid which I believe one is from the ignition on the steering wheel for starting and one goes to the positive terminal on the coil to supply +12 while cranking. In order to "hotwire" the starter solenoid with another source of +12 to that dual spade connector, one of those wires has to be removed to gain access to a connector. I chose to remove the wire coming from the ignition and hooked my momentary switch wire to that spade terminal.
2. The wire coming from the ignition switch that I removed was a PO-installed heavy wire going to the front of the bus and one of those typical relay circuits to provide more power/current to the solenoid which was done, I suspect, because the ignition switch was getting worn out. Again, that's the wire I pulled off the solenoid. The wire to the coil is still attached.
3. When this happened, I was no longer cranking the engine with my momentary button. The engine was stationary. I then turned on the toggle switch to provide +12 to the positive terminal of the coil. I realize if the points happened to be in a closed position then this would fairly quickly start to overheat my coil but I did it just to verify my little LED indicator and switch were working properly. The regular VW horn activated instantly when I turned on the power to the coil via the toggle switch. I cannot imagine how that would make the horn suddenly turn on. _________________ 1975 Westy, Serenity w/FI
1975 Westy, Jack Sparrow w/FI
1979 Kombi, Pistachio w/FI
1979 Kombi, Oliver wFI
1977 Tin top camper, Cosmos w/FI
1974 Westy, Garfield w/ Dual Solex PDSIT
1973 Tin top camper, Bart
1974 gutted Dorper Casper w/ Dual Solex PDSIT
1975 Westy, Stella w/single progressive Weber
1979 Super Beetle, Penelope w/FI
1967 Fastback, Green Hornet w/dual Solex |
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busdaddy Samba Member
Joined: February 12, 2004 Posts: 51128 Location: Surrey B.C. Canada, but thinking of Ukraine
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Posted: Sat Aug 01, 2020 8:00 am Post subject: Re: Hot wiring and I apply +12v battery to + on coil the horn beeps? |
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When the steering lock is engaged it completes the horn circuit, that usually happens when the key is off so it doesn't matter, powering the ignition system from the back disturbs the balance of the universe. _________________ Rust NEVER sleeps and stock never goes out of style.
Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!
Слава Україні! |
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kinggeorge13 Samba Member
Joined: May 24, 2013 Posts: 95 Location: Fort Langley, BC, Canada
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Posted: Sat Aug 01, 2020 8:36 am Post subject: Re: Hot wiring and I apply +12v battery to + on coil the horn beeps? |
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busdaddy wrote: |
When the steering lock is engaged it completes the horn circuit, that usually happens when the key is off so it doesn't matter, powering the ignition system from the back disturbs the balance of the universe. |
Thanks Busdaddy! I did not know that! There is a plenty good chance that steering wheel was turned after we parked it and therefore engaged the steering wheel lock. That would explain exactly what I'm seeing. I guess the easy fix would be do to these things with the key in and turned so the steering is definitely unlocked.
I did wonder if there was some theft-deterrent system installed by a PO that was somehow hooked up to detect this kind of thing but I really did not think it was likely. So this is kind of the VW way of alarming the bus in case someone tries to hot-wire it? (although I never really understood the point of hotwiring a bus to steal it if the steering wheel locks without the key but that's not really my concern right now since it's sitting on my driveway and I do have the key).
Thanks! I will check this today. _________________ 1975 Westy, Serenity w/FI
1975 Westy, Jack Sparrow w/FI
1979 Kombi, Pistachio w/FI
1979 Kombi, Oliver wFI
1977 Tin top camper, Cosmos w/FI
1974 Westy, Garfield w/ Dual Solex PDSIT
1973 Tin top camper, Bart
1974 gutted Dorper Casper w/ Dual Solex PDSIT
1975 Westy, Stella w/single progressive Weber
1979 Super Beetle, Penelope w/FI
1967 Fastback, Green Hornet w/dual Solex |
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mikedjames Samba Member
Joined: July 02, 2012 Posts: 2736 Location: Hamble, Hampshire, UK
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Posted: Sat Aug 01, 2020 9:44 am Post subject: Re: Hot wiring and I apply +12v battery to + on coil the horn beeps? |
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Thanks. I always wondered why when my bus caught fire and some wiring melted, the horn sounded until I disconnected the leisure battery..
I thought it was some kind of death scream.
It only took a day to clean up and get back on the road. _________________ Ancient vehicles and vessels
1974 VW T2 : Devon Eurovette camper with 1641 DP T1 engine, Progressive carb, full flow oil cooler, EDIS crank timed ignition.
Engine 1: 40k miles (rocker shaft clip fell off), Engine 2: 30k miles (rebuild, dropped valve). Engine 3: a JK Preservation Parts "new" engine, aluminium case: 26k miles: new top end.
Gearbox rebuild 2021 by Bears.
1979 Westerly GK24 24 foot racer/cruiser yacht Forethought of Gosport.
1973 wooden Pacer sailing dinghy |
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ToolBox Samba Member
Joined: January 27, 2004 Posts: 3439 Location: Detroit, where they don't jack parts off my ride in the parking lot of the 7-11
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Posted: Mon Aug 03, 2020 10:17 am Post subject: Re: Hot wiring and I apply +12v battery to + on coil the horn beeps? |
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kinggeorge13 wrote: |
busdaddy wrote: |
When the steering lock is engaged it completes the horn circuit, that usually happens when the key is off so it doesn't matter, powering the ignition system from the back disturbs the balance of the universe. |
Thanks Busdaddy! I did not know that! There is a plenty good chance that steering wheel was turned after we parked it and therefore engaged the steering wheel lock. That would explain exactly what I'm seeing. I guess the easy fix would be do to these things with the key in and turned so the steering is definitely unlocked.
I did wonder if there was some theft-deterrent system installed by a PO that was somehow hooked up to detect this kind of thing but I really did not think it was likely. So this is kind of the VW way of alarming the bus in case someone tries to hot-wire it? (although I never really understood the point of hotwiring a bus to steal it if the steering wheel locks without the key but that's not really my concern right now since it's sitting on my driveway and I do have the key).
Thanks! I will check this today. |
YOu could add a diode to the stock coil wire to avoid this in the future. Someone smarter than me could give you the correct diode value. |
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JamesT Samba Member
Joined: September 08, 2003 Posts: 603 Location: East Sooke, BC, Canada
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Posted: Tue Aug 04, 2020 8:38 am Post subject: Re: Hot wiring and I apply +12v battery to + on coil the horn beeps? |
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Since the ignition coil is not fused, and your horn is, you could pull the fuse for the horn while using your hot wiring rig to avoid this in the future.
Or if you remove the hot wire from your coil, you could eliminate the problem of back feeding everything. The downside to that is that your charging system won't work while you test unless you energize the field, so the fuse is probably your best option. _________________ -James T
1968 Kombi (Weekend warior project)
1982 Rabbit Pickup (Forever a project) |
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