General electrical question
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Road Master
Joined: Aug 2007
Posts: 848
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From:
General electrical question
I have a 1990 FLHTCU with electrical problems and I have a general question..
Symptoms...
Sometimes the starter hesitates and I get a little compression pop before it starts. Other times it turns over very quickly and starts instantly
I have a fluctuating voltmeter. Especially when I grab the front brake and use the blinkers. It jumps all over the place.
2 days ago I went out on a 150 mile ride with no problems at all. Later that night I went to get coffee and my radio stopped responding. It was stuck on and none of the controls worked. I then got a terrible noise when I grabbed the front brake. Then a loud buzz, the tach jumped to 8K, the voltmeter dropped to 2v, the bike almost stalled and the radio when dark.
Same thing happened about 30 minutes later. The only thing I did different at night was I had my spotlights and my side bag lights on.
I took the bike apart and noticed my 5 amp POD fuse was blown and the 5 amp power fuse on my radio is blown. I replaced the fuses and the radio is back to working fine. I then replaced the 4 circuit breakers under the fairing. I started the bike and turned every accessory on and felt the wires to the circuit breakers. The single red wire on the breaker to the left (when facing the bike) with the 3 red wires on it was hot. Not burning hot but certainly very warm.
So.. on to the general question...
Would bad battery cables cause these problems? The cables on my bike look to be original.They are date coded 70033-89. I removed them and peeled back some of the jacket and they are green/white with oxidation where they are crimped to the lugs. The copper gets better as you peel back the jacket.
Symptoms...
Sometimes the starter hesitates and I get a little compression pop before it starts. Other times it turns over very quickly and starts instantly
I have a fluctuating voltmeter. Especially when I grab the front brake and use the blinkers. It jumps all over the place.
2 days ago I went out on a 150 mile ride with no problems at all. Later that night I went to get coffee and my radio stopped responding. It was stuck on and none of the controls worked. I then got a terrible noise when I grabbed the front brake. Then a loud buzz, the tach jumped to 8K, the voltmeter dropped to 2v, the bike almost stalled and the radio when dark.
Same thing happened about 30 minutes later. The only thing I did different at night was I had my spotlights and my side bag lights on.
I took the bike apart and noticed my 5 amp POD fuse was blown and the 5 amp power fuse on my radio is blown. I replaced the fuses and the radio is back to working fine. I then replaced the 4 circuit breakers under the fairing. I started the bike and turned every accessory on and felt the wires to the circuit breakers. The single red wire on the breaker to the left (when facing the bike) with the 3 red wires on it was hot. Not burning hot but certainly very warm.
So.. on to the general question...
Would bad battery cables cause these problems? The cables on my bike look to be original.They are date coded 70033-89. I removed them and peeled back some of the jacket and they are green/white with oxidation where they are crimped to the lugs. The copper gets better as you peel back the jacket.
Outstanding HDF Member
Joined: Jul 2008
Posts: 2,115
Likes: 5
From: SoCal
sounds more like a possible bad voltage regulator to me. from what I've heard, when those things go they cause all sorts of wacky problems
if it is your VR you'll want to figure it out quick and replace it because when it kicks out it can take a lot with it. Easier to replace just that
and why not just replace your battery cables while you're at it
if it is your VR you'll want to figure it out quick and replace it because when it kicks out it can take a lot with it. Easier to replace just that
and why not just replace your battery cables while you're at it
The first rule to follow when diagnosing problems is to look at what is not stock on your bike. In your case you said you have "side bag lights", if I was the tech working on your bike I would check the wiring to these and make sure everything is O.K. or I would disconnect them and ride for awhile (days) and see if the problem repeats itself. I don't know where whoever hoked them up picked up power for them, but if they picked up power from the other lights it might be possible that there is a short somewhere.
Thread Starter
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Road Master
Joined: Aug 2007
Posts: 848
Likes: 8
From:
The first rule to follow when diagnosing problems is to look at what is not stock on your bike. In your case you said you have "side bag lights", if I was the tech working on your bike I would check the wiring to these and make sure everything is O.K. or I would disconnect them and ride for awhile (days) and see if the problem repeats itself. I don't know where whoever hoked them up picked up power for them, but if they picked up power from the other lights it might be possible that there is a short somewhere.
No problem. hat is kind've a weird place for a toggle switch, that right there would leave me to assume that they spliced into the wiring harness to pick up power for them. Good luck and keep us posted.
Thread Starter
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Road Master
Joined: Aug 2007
Posts: 848
Likes: 8
From:
The wiring for the aux light bars on the luggage bars is a pro job. It is tapped into a power out connector under the side cover on the clutch side. That hot lead is run to a toggle mounted on the side cover next to the rear schraeder air shock valve. The lights themselves are grounded to the chassis by way of the luggage crash bars.
Outstanding HDF Member
Joined: Jul 2009
Posts: 2,447
Likes: 0
From: Danville Va, Providence NC
So are you saying that when you grab the brake, the volt gauge goes crazy? That sounds like a short in the lighting. Until you pull the brake, the light is dead, no juice there. When you pull the brake, you send current to the lights. Perhaps there is a bad spot there in the wiring. If you have replaced all the fuses/breakers, then crank it up, and watch the gauge as you try each electrical item. One at a time. Perhaps you will get lucky and see which one is the demon.
Good luck, electrical problems can be a real Biatch!
RD
Good luck, electrical problems can be a real Biatch!
RD
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Thread Starter
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Road Master
Joined: Aug 2007
Posts: 848
Likes: 8
From:
So are you saying that when you grab the brake, the volt gauge goes crazy? That sounds like a short in the lighting. Until you pull the brake, the light is dead, no juice there. When you pull the brake, you send current to the lights. Perhaps there is a bad spot there in the wiring. If you have replaced all the fuses/breakers, then crank it up, and watch the gauge as you try each electrical item. One at a time. Perhaps you will get lucky and see which one is the demon.
Good luck, electrical problems can be a real Biatch!
RD
Good luck, electrical problems can be a real Biatch!
RD
When I first start it, it reads about 14v constant
After it warms up it reads about 12.5v
With the headlight on it reads about 11.5v-12v
If I put either of the blinkers on it fluctuates between 8v and 11v
If I grab the front brake it drops to 6v-8v
If I have one of the blinkers on and the front brake is grabbed it drops to 2v-4v
Keep in mind, the actual voltage at the battery is a consistant 12.7v at idle and 14.1v at 2500rpms. I hooked up a Fluke meter to it to test it.
The reason the voltage drops so much when grabbing the front brake is that its connected to the anti-dive solenoid which draws a fair amount of current.
I went through the entire bike again last night and I added an additional ground for my voltage regulator. I am thinking the problems I am having are due to my original 20 year old battery cables. Although they looked good on the outside, they were not good on the inside.
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Cruiser
Joined: Aug 2008
Posts: 191
Likes: 0
From: Danville, KY
Voltage Drop
If you think it's a cable, first take your Fluke meter and clip 1 lead on battery post , then the other lead on the Starter connection. Then do you standard tests you have been doing, if it is that section of wire/connectors that is bad you will read a voltage drop across the cable, with no load meter should read zero volts, loaded/testing should be close to zero, maybe only a fraction of a volt. If that checks OK , then try the same voltage drop test on the neg lead, from battery post to good frame ground, same results on drop should be readable. If both OK you can back up to the pos post test and try and get the other lead to one side of your main fuse. Could be a bad wire/connector or a bad connection at you main fuse connection. The point is, where you get a voltage drop voltage reading is where you have a poor connection, ie.. a resistor, also while your checking each point , try and wiggle the wire and the connection point. If you can't find anything here , post what you did find and we can go from there.
Tourer
Joined: Mar 2010
Posts: 400
Likes: 4
From: southern ontario
I had a similiar problem with my 89 FLHTCU a few years ago. My battery shorted out inside. The bike started but ran like crap. Tach was jumping to max,radio was buzzing and no controls worked at all. Put new bat in and solved problem. Just my .02 cents