Author Topic: 1980 iron head wiring diagram.  (Read 700 times)

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Offline Crawler

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1980 iron head wiring diagram.
« on: July 10, 2019, 05:15:58 AM »
anyone have a wiring diagram for an 1980 sportster. I have some sketchy turn signal/tail light wiring to trace and my service manual hasn't arrived yet. thanks in advance.

Offline Burnout

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Re: 1980 iron head wiring diagram.
« Reply #1 on: July 10, 2019, 11:34:53 AM »
Purple and Green are turn signals
Red is Stop
Blue is running lights.
They don't call me Ironhead Rick just because I'm "hard headed"

Offline Crawler

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Re: 1980 iron head wiring diagram.
« Reply #2 on: July 10, 2019, 12:22:21 PM »
thanks Burnout. the previous owner spliced in a trailer wiring harness to control the brake lights and turn signals. the brake light works fine but just with the front brake and not the rear brake pedal and non of the signals work. I have some wire tracing to do. I'm hoping to have a service manual in a few days but i'd like to get tinkering.
« Last Edit: July 10, 2019, 12:29:08 PM by Crawler »

Offline Burnout

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Re: 1980 iron head wiring diagram.
« Reply #3 on: July 10, 2019, 08:52:26 PM »
The rear brake light switch is wired in parallel to the front switch and gets power from an orange wire
They don't call me Ironhead Rick just because I'm "hard headed"

Offline Crawler

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Re: 1980 iron head wiring diagram.
« Reply #4 on: July 11, 2019, 07:07:23 AM »
So I was messing with the wiring last night. If I hold the signal button in on the right hand side I have front and rear signals with the head light in the off and on position on the ignition switch. On the left side I have no signals when holding the button it dose not matter if the ignition is turned to have the headlight on or off. with the ignition in headlight off position when I hit the left signal the head light blinks :emoGroan: guess I have my work cut out for me.  is it common on the old iron head to have to keep holding down the signal button for the turn signals?

Offline Hossamania

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Re: 1980 iron head wiring diagram.
« Reply #5 on: July 11, 2019, 07:46:52 AM »
Sounds like you have some errant grounds and probably a short or two going on.
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Offline Crawler

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Re: 1980 iron head wiring diagram.
« Reply #6 on: July 11, 2019, 08:01:07 AM »
Hossamania. your probably right. The wiring is a mess with 30 years of splicing going on. once I get the manual I'm going to go over it wire by wire and fix the junk.


Offline Burnout

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Re: 1980 iron head wiring diagram.
« Reply #7 on: July 11, 2019, 09:09:05 AM »
So I was messing with the wiring last night. If I hold the signal button in on the right hand side I have front and rear signals with the head light in the off and on position on the ignition switch. On the left side I have no signals when holding the button it dose not matter if the ignition is turned to have the headlight on or off. with the ignition in headlight off position when I hit the left signal the head light blinks :emoGroan: guess I have my work cut out for me.  is it common on the old iron head to have to keep holding down the signal button for the turn signals?

Blue wire is headlight power from the breaker
That goes to the high beam switch and from there goes to the headlight on the Yellow and White wires
Should be no other connections to those wires except the high beam indicator light.
They don't call me Ironhead Rick just because I'm "hard headed"

Offline rigidthumper

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Re: 1980 iron head wiring diagram.
« Reply #8 on: July 11, 2019, 11:11:30 AM »
Old style turn signals used a car style flasher, that relied on push & hold to apply voltage to the bulbs. As the current ran through the bulbs, ( lamps on) the flasher would heat up, and break contact (bulbs off) until it cooled off enough to make contact again ( bulbs on). This resulted in the clicking sound from the flasher.
If the current draw is low, bulbs will either not blink, or blink at a slow rate.

Offline Crawler

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Re: 1980 iron head wiring diagram.
« Reply #9 on: July 11, 2019, 12:05:56 PM »
rigidthumper thanks for letting me know about having to hold in the signal button. I do have a car style flasher in the head light bucket. I could here it clicking on and off. the blinkers that work are pretty slow.

Offline Hossamania

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Re: 1980 iron head wiring diagram.
« Reply #10 on: July 11, 2019, 01:31:36 PM »
Measure standing voltage at the battery, and running voltage. Make sure the basics are in good order.
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Offline Crawler

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Re: 1980 iron head wiring diagram.
« Reply #11 on: July 13, 2019, 08:10:10 AM »
Hossamania  my standing voltage was 12.35  and my running voltage was 12.37 but when higher (13.48) as I rolled on the throttle.

Offline rigidthumper

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Re: 1980 iron head wiring diagram.
« Reply #12 on: July 13, 2019, 08:37:24 AM »
Generator systems barely break even at idle, do a decent job from 2000 up.

Offline Crawler

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Re: 1980 iron head wiring diagram.
« Reply #13 on: July 15, 2019, 04:43:04 AM »
I managed to dig into the wiring this weekend. I cleaned out 40 years of poor splicing and managed to get the signals to work, tail light and head light all working good. Next up is the faulty brake hydraulic pressure switch.

Offline db13

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Re: 1980 iron head wiring diagram.
« Reply #14 on: August 30, 2019, 09:17:46 PM »
Try here    https://www.classiccycles.org/    they may have what you need