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Reverse Polarity Timing Light

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PAUL161

PAUL161

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I ruined my Innova timing light, I hooked it up correctly to the battery but it wouldn't do all functions as the car is positive ground, I switched the leads for positive ground and the light quit working! Is there a dial-back light that works on a positive ground system? My old light works fine, it's just not a dial back! PJ
 
John Turney said:
When you switched the leads for positive ground, did you reverse the spark pickup?
Click to expand...
No John I didn't, should I have? I just left it on the plug wire as the arrow indicated, did I goof up? PJ
 
I think John is right.
 
Thanks for the input, I'll have to give that a try. PJ
 
I'm dubious, but curious as well. The spark-plug fires with a high voltage from the coil, the light's pick-up is triggering from induction, I'll be surprised if reversed it would make a big difference if the coil is up to snuff.
 
DrEntropy said:
I'm dubious, but curious as well. The spark-plug fires with a high voltage from the coil, the light's pick-up is triggering from induction, I'll be surprised if reversed it would make a big difference if the coil is up to snuff.
Click to expand...
New coil Doc, just installed it. I also am dubious as the pickup grabs the high voltage going through the wire, I don't think it matters which way it's going, but, I'll check it out, nothing to turn it around. :encouragement:
 
But those pickups usually do have an arrow that is supposed to point toward the plug. Must be some reason for that.
 
By reversing the primary supply wires on the light, it's conceivable the gun's circuitry is fried. Ordinarily it should work when powered even with an external 12V battery, proper positive and negative leads connected. The pick-up is just an induction coil and senses HV discharge, independent from the gun's power source.

Again, I contend the inductive pick-up should "see" the HV discharge, as long as the coil is in good nick. It may be a weaker signal when the toroidal coil is reversed but I'd think it would still trigger.
 
From what I read doing a quick browse of the net, if turning the induction clip around doesn't "trick" it, then you're most likely out of luck. I saw on a forum where the manufacturers help line told another guy they don't work with positive ground too.
 
Mine have worked on both negative and positive ground cars. Never thought much about it!
 
I'm with Doc, I've had a couple of timing lights and never had a problem with positive or negative ground.
 
My personal timing light works either way, but it is 30 some years old and not digital. the digital part I think can make the difference since most of that stuff can be polarity sensitive.
 
I've never had a digital one. What is the advantage of having a digital timing light?
 
Something got fried in the dial back I had, it works no more! I've used the old plain, simple light I've had for years with no problems, so, until someone comes up with a better solution that works without spending a lot of money I'll continue using it. My old tractors and the TF are the only things I use a light on and that's pretty rare, I think spending a couple hundred bucks for a new light just for the TF is a little overboard, so I'll stick with the old one I have. Thanks for all the comments, much appreciated. PJ
 
Paul, your 'solution' is smart. No need for another light, IMHO. it's a "run what ya brung" deal.

Mine is older than Mikes. Off brand: "Autotune Model 4138" by name. Inductive, yes. Electronic? No.

Had a couple Craftsman dial type in the shop, they worked on anything we used 'em on, but again they were older, non-microcircuitry units.

Heck, I default to a 12V test light to static time my own cars most of the time, anyway. ;)
 
Do the same thing for static timing, I have a length of wire with a clip on one end and a bulb on the other I ground to a bare spot on the engine or car. Use it to trace where the juice is disappearing too when tracking electrical problems. Oh for the days when finding and fixing didn't need $200k in computerized diagnostic equipment...
 
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