red22
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| posted on 23/12/12 at 04:31 PM |
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Am I missing something........?
My wifes KA decided to start sulking for xmas by refusing to let the side lights or dash illumination to work. No biggie I thought its got to be the
fuses or the switch. So out with the Haynes and my meter and a delve into the fuse box only to find no fuses blown. Oh well got to be the switch then
I thought, but as I will admit to being slightly lazy I checked it from the fuse box. So with the fuses out I get continuity through the switch so
thats ok, right? Apparently not. So the fuses are ok the switch is ok and I was stumped. I put the fuse back on the feed to the switch and measure 12v
going in and 12v coming out of the switch when its switched but put the fuses in on the feeds away to the lights and the voltage drops to nothing.
This seems pretty odd never had this happen to me before. After a bit of googleing turns up nothing I decided to take the column apart and double
check the wiring. This just left me more confused than at the begining. I have 12v to the connector that goes to the switch and on the switch itself i
have continuity between the contacts, which would indicate the switch is definitely ok but still no dice when its in circuit. If I put a jumper on the
connector so its taking the place of the swictch all works ok.
So it has to be the switch thats at fault, but how can it be ok on a continuity test but not in circuit? Please feel free to expand my knowledge and
let me know why its would do that. Thanks.
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loggyboy
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| posted on 23/12/12 at 04:34 PM |
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FLuke that all the bulbs have blown?
Mistral Motorsport
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Stott
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| posted on 23/12/12 at 05:00 PM |
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Depends on how you're measuring the continuity of the switch. If you are using a magic screwdriver, or meter on diode check with a beep, it will
show continuity but if you measure using the ohms scale on the meter you may find there is high resistance across the joint.
Switch to ohms, measure your leads, then the switch. Ideally it will be the same as the leads or marginally more, like 0.1 ohm more than the leads
measured.
You may have to try strip the switch and clean the contacts if possible.
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red22
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| posted on 23/12/12 at 05:07 PM |
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Using a proper DMM. Registers about 0.5 ohms across the switch switch isn't exactly excessive but definitely doesn't want to know when all
connected up. Just never had it where the switch is doing what switches are supposed to do but not working in circuit.
No all the bulbs are ok.
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Moorron
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| posted on 23/12/12 at 06:05 PM |
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Not sure if this will help but the Ford Puma has a known fault with the light switch stalk. As they share parts with the KA i assume you have the same
problem as i had a few years ago.
Biggest issue is you have spotted the problem, my Girlfriends didnt notice her dash lights not working for weeks meaning she was driving about with no
rear lights on also. The front worked as the main headlights work off a second indipendant circuit, but the front side lights didnt work but you
couldnt tell.
I removed the switch the first time round and found one in the scrap yard but this also failed some years later so i ripped the switch apart and
'bent' the contact so they would make contact again, they just wear out of springyness over time. Not fun to do and required some
desoldering to remove the light switch part from the rest of the unit i removed from around the steering wheel and then solder it back up.
This is where i managed to stick a screwdriver 1" into my left hand so be carefull! Still didnt go to the hospital as i wanted extra man points.
ALSO NOTE, there are 2 different types of stalks and they arent swappable but look the same, so be sure to get the right one if you are buying.
Sorry about my spelling, im an engineer and only work in numbers.
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omega 24 v6
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| posted on 23/12/12 at 08:38 PM |
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Usually when you get this 12v reading and then nothing when the bulbs are then you have a severely compromised cable or connection. Think of the
corroded or damaged area of the cable as being like a blocked pipe. The water is still there but it won't pass the restriction. Run a temp wire
from where you are metering the voltage drop to the upstream part of the circuit and see if the bulbs light.
If it looks wrong it probably is wrong.
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red22
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| posted on 24/12/12 at 11:55 AM |
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I get it that that switch is at fault just that 0.5 ohms resistance across the switch shouldnt make that much difference. just my luck that all of the
cheap places are out of stock at the mo.
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Moorron
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| posted on 24/12/12 at 05:20 PM |
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I also had this problem on one of my own cars many years ago, the engine would just cut out so i thought i would check the after market immobiliser
and it showed 12v at the coils, so i rulled it out. Until i gave up with it randomly switching off and took it to a car electrics place. They told me
it was the immobilser so i questioned them and they said it was a bad contact on one of the relays which showed 12v at the plug UNTIL you loaded it up
and then it arced and lost contact.
You may have low resistance but as soon as the contact gets a load of amps it will rise.....maybe 
Sorry about my spelling, im an engineer and only work in numbers.
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