Electrical problem on 1990 FLHTC

9490 Views 8 Replies 6 Participants Last post by harleymike1223, Dec 29, 2014

harleymike1223

Discussion Starter · Dec 28, 2014 (Edited)

I have a problem on my 1990 Electra glide with power to my fairing. The battery voltage is good,the power to the circuit breaker from the battery under the fairing is good. When I turn on the ignition the voltage to my gauges, lights and everything under the fairing drops to around 10 volts but my battery is still at 12 volts. I suspect a bad ignition switch but am looking for someone who might know or have had a similar experience. Voltage is so low at idle that my turn signals won't come on and the lights go dim/bright with the turn signal pulses. Radio also crackles due to low voltage. When I rev the bike way up the turn signals work. Bike is charging at 13.5 volts at idle so the charging system is definitely working. Would a bad battery possibly cause the problem. Also sometimes bike won't start with switch but I have a push button directly on the starter solenoid and when I push that the bike starts right up. Definitely a voltage problem under the fairing.

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Rohan

· #2 · Dec 28, 2014

I would look at the voltage regulator. It sits at the bottom of the frame in between the down tubes. Also, a new battery might not be a bad idea. Ignition on, voltage will drop a little naturally because of the load. Running though, it shouldn't be doing what you are describing. Dave will probably have more knowledge of this and be able to help further but these are my 2 cents for now without pulling out any wiring diagrams. As far as the actual ignition switch not working, that is common. No harm in using a push button directly on the starter. I used one on a custom Softail for many years without a problem.

Welcome to the forum!

-Rohan

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harleymike1223

Discussion Starter · #3 · Dec 28, 2014

Thanks for the info. I will check out the regulator and see what else I can find.

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chasarms

· #4 · Dec 28, 2014

Wiring - especially the couplings - just gets old. They corrode and pick up a lot more resistance creating voltage drops. I'd guess you have a corroded wire or coupling (at least one) somewhere. There's no cure but to get a meter and start narrowing down.

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harleymike1223

Discussion Starter · #5 · Dec 28, 2014

Forgot to add that with engine off and ignition on the voltage on the ignition and accessory wires from the ignition switch wil be at roughly 10.5 to 11.0 volts and battery's will remain at 12 volts. The ignition voltage was checked at the circuit breakers due to the difficulty getting to the ignition switch with the inner fairing still on.

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FritzHD

· #6 · Dec 29, 2014

Have your battery load tested, chances are it's on the way out.

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Pete

· #7 · Dec 29, 2014

The voltage at the battery, with the bike not running and the battery not under any load should be 12.6 volts - not 12 volts. Even if the battery is failing, if the bike is running and the alternator is charging the batter at 13.5 volts, as you described, voltage at the various electrical switches and devices should be in the 13.5 voltage range too.

The first thing that I would be to look at the ground from the battery to the frame. A bad ground can cause all sorts of electrical issues. I would also recommend having the battery load tested, but I don't think that is your problem.

Any electrical issue that is draining that much current should be producing some heat. You can check the switch and even the wiring inside the fairing with an infrared thermometer. Often you can find a bad connection because it will be warmer than the surrounding wiring, connections and switches.

Pete

harleymike1223 said:
Forgot to add that with engine off and ignition on the voltage on the ignition and accessory wires from the ignition switch wil be at roughly 10.5 to 11.0 volts and battery's will remain at 12 volts. The ignition voltage was checked at the circuit breakers due to the difficulty getting to the ignition switch with the inner fairing still on.

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Dan89flstc

· #8 · Dec 29, 2014

If you are getting low voltage readings at the ignition switch, then the issue is not "definitely under the fairing"...

The first things to do are to make sure the battery if fully charged and have it load tested.

Look for the location of the voltage drop with your voltmeter,

Touch the positive probe to the positive post on the battery, and touch the negative post to each post on the main breaker, then follow the wire from the main breaker, and touch the probe to the terminal where the wire connects to the ignition switch.

All of your readings should be less than .5V

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harleymike1223

Discussion Starter · #9 · Dec 29, 2014

Thanks for the ideas guys. I'll have to investigate further, maybe start with a different battery, that would be easiest.

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