Coil primary input volts


Information and questions on GL1200 Goldwings (1984-1987)
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jwebfournow
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Coil primary input volts

Post by jwebfournow »



Hi everyone! Need advice on a new purchase. 1984 aspencade no spark cyls 1/2. Pulled coils tested primary and secondary side within specs. Checked pulsar wire s within specs. Checking voltage at bu/y wire left coil 9.8 v BL/w 12v, coil for cyls 3/4, check y/bu wire r coil cyls 1/2, 0 volts, bl/w has 12v. Question is should'nt y/bu wire for right coil for cyls 1/2 also have at least 9.8 v same as left coil cyls 3/4? I know y/bu wire feeds tach signal. any ideas? Lack of voltage at y/bu explain no spark to cyls 1/2?



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virgilmobile
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Re: Coil primary input volts

Post by virgilmobile »

Unplug the ignition module.Check for the primary coil volts on both coils.They both should be near battery volts.If one goes to zero when the module is plugged back on,the module is bad.It uses electronics to switch the primary winding to ground to make it spark...That part may be shorted.If so,that generally will overheat and damage the ignition coil.

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Maz
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Re: Coil primary input volts

Post by Maz »

jwebfournow wrote:Hi everyone! Need advice on a new purchase. 1984 aspencade no spark cyls 1/2. Pulled coils tested primary and secondary side within specs. Checked pulsar wire s within specs. Checking voltage at bu/y wire left coil 9.8 v BL/w 12v, coil for cyls 3/4, check y/bu wire r coil cyls 1/2, 0 volts, bl/w has 12v. Question is should'nt y/bu wire for right coil for cyls 1/2 also have at least 9.8 v same as left coil cyls 3/4? I know y/bu wire feeds tach signal. any ideas? Lack of voltage at y/bu explain no spark to cyls 1/2?
It's possible that the coil showing 0 volts is being grounded by the module as it should be before the spark. Turn the motor over a bit by hand to check while watching your meter. If the lead still shows 0v whilst turning the motor over, then I agree with Virgil. If you see 12v (or 9.8v) at some point whilst turning the motor, that is the point at which the spark plugs fire, and is normal.
Maz
Ironically, Common Sense is the LEAST common of all senses!

jwebfournow
Posts: 51
Joined: Sat May 27, 2017 12:27 pm
Location: California
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Re: Coil primary input volts

Post by jwebfournow »

Okay did that ,no difference. Also checked continuity on y/bu from coil wire to 4 pin connector were ignition module plugs in has continuity ,obviously no voltage, did same for bu/y l coil wire to 4 pin connector good continuity and voltage. As far as I can figure from wiring schematic y/bu also goes back into left side fairing harness and up to gauge cluster tach, when I had it running I am sure I saw the tach working. Wondering if problem might be in gauge. History on bike, 45k, po did poorboy conversion was riding and just started to run on 3/4 cyls nursed it home was beyond his troubleshooting abilities and voila! I have it now

jwebfournow
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Re: Coil primary input volts

Post by jwebfournow »

Also had meter connected to y/ bu wire and cranked engine still no fluctuation in voltage.

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virgilmobile
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Re: Coil primary input volts

Post by virgilmobile »

I don't have my schematic on my phone to verify but if you unplugged the ignition module and still have no volts...that's a good indicator that that line is shorted to ground.
Remove the left pocket and cover to the right of it.In the bottom you should see a interconnect plug.Its a pain but unplug it.It comes loose between the faring and the frame.This will disconnect that wire from the coil to the tach.Retest for volts again.This separates the problem from the bike or the faring.
I assume that with the key off,that wire with no volts shows a short to ground.

jwebfournow
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Re: Coil primary input volts

Post by jwebfournow »

Maybe a lesson to be learned. Even though primary and secondary sides of 1/2 coil checked out to be in specs, I decided to change things around, I moved the y/bu wire along with its BL/w over to left coil got good spark,then moved bu/y wire and the bl/w over to r coil got no spark, so coming to the conclusion that even though the cyls 1/2 coil ohmed out correctly on both primary and secondary sides the coil is still bad. I will get another coil and give it a try and let you all know.

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virgilmobile
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Re: Coil primary input volts

Post by virgilmobile »

Its possible that even tho the primary has normal resistance the side from the module is shorted to ground.A quick continuity test would reveal this.The ground would be the mounting frame.There should be no continuity from any wire connection to this mount.
Good find by the way.

jwebfournow
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Re: Coil primary input volts

Post by jwebfournow »

Back to tell you all that it turns out it was the coil, replaced and fired right and sounds good , now the dreaded part of putting all the pin connectors all back in there proper positions. Thanks for all the suggestions. Even though the coil checked out according to the manual, sometimes you just have to try another part.

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virgilmobile
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83 GL1100 I
83 GL1100 standard
84 GL 1200 I

Re: Coil primary input volts

Post by virgilmobile »

Great.I'm glad you confirmed the problem by testing(swapping coils).Good test method.

jwebfournow
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Joined: Sat May 27, 2017 12:27 pm
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Re: Coil primary input volts

Post by jwebfournow »

Bike is now running but with some more issues, someone has been into the carbs #4 was not running well at idle, turns out idle/air screw not even there ,replaced and no difference dirty pilot jet probably, vacuum hose also collapsing on same cyl, ign control module getting hot,then starts to runs rough then dies,well at least I have spark at all 4, thank goodness I didn' t give to much for the bike. So pulling carbs and going through them will be next. :(



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