1990 Ultra Classic Problem!!
Cruiser
Joined: Nov 2007
Posts: 216
Likes: 2
You have voltage drops between the battery and the accessory circuit where the stereo connects to. The voltage is probably dropping down below the cutoff voltage for the stereo because of the current surge of the cold filaments in the brake light bulbs and also the anti dive solenoid. Follow the wiring in the manual, and pay particular attention to the ring lugs on the circuit breakers inside the fairing. Been there before with my own Ultra and a few others. Voltage drops due to corrosion are the culprits.
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Road Master
Joined: Aug 2007
Posts: 848
Likes: 8
From:
You have voltage drops between the battery and the accessory circuit where the stereo connects to. The voltage is probably dropping down below the cutoff voltage for the stereo because of the current surge of the cold filaments in the brake light bulbs and also the anti dive solenoid. Follow the wiring in the manual, and pay particular attention to the ring lugs on the circuit breakers inside the fairing. Been there before with my own Ultra and a few others. Voltage drops due to corrosion are the culprits.
Thanks... John G
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Road Master
Joined: Aug 2007
Posts: 848
Likes: 8
From:
You have voltage drops between the battery and the accessory circuit where the stereo connects to. The voltage is probably dropping down below the cutoff voltage for the stereo because of the current surge of the cold filaments in the brake light bulbs and also the anti dive solenoid. Follow the wiring in the manual, and pay particular attention to the ring lugs on the circuit breakers inside the fairing. Been there before with my own Ultra and a few others. Voltage drops due to corrosion are the culprits.
Cruiser
Joined: Sep 2009
Posts: 168
Likes: 1
From: Central Mass
+1 on what bigtone is saying and remember antidive solenoid works with FRONT BRAKE ONLY ,would it make sense for a front anti dive unit to work when you hit the rear brake ??. Get the HD manual if you dont have one.You must remove fairing cap (front side)remove headlight and then there are 4 -7/16" nuts to loosen ,works best with sears or other flex head rachet wrench not socket.
Stan
Stan
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Road Master
Joined: Aug 2007
Posts: 848
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would bad grounds also cause the voltmeter to jump all over the place. I took the bike out for the first time yesterday. The voltmeter reads 12.5 volts when I am driving. It sits at 12 volts at idle. If I apply the front brake it drops down to around 2-4 volts. If I put the blinkers on it fluctuated between 4 and 10 volts. If I increase the idle to around 2000 rpms the radio will not shut off when the front brake is applied. Does this still sound like a bunch of bad grounds under the fairing?
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Road Master
Joined: Aug 2007
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I removed the fairing and the radio today so that I could get to the ground busbar that is mounted on the top of the anti-dive solenoid. What a pain to get at those little .250 female push on connectors. Anyway, I noticed a few things.
There are 2 large black ground wires connected to that bar. One of them goes directly to a large ring terminal that is sandwiched between the fork tree and the fork riser.
When I went to remove it from the ground block it literally fell off with the slightest amount of pressure. It appears that one of the little curved over retention tabs was broken so that ground was not secure. They were all clean though. I am crimping on a new connector tomorrow and all the contacts are clean now. My guess is that it is the problem. I will post my results tomorrow once I get it all sorted out.
There are 2 large black ground wires connected to that bar. One of them goes directly to a large ring terminal that is sandwiched between the fork tree and the fork riser.
When I went to remove it from the ground block it literally fell off with the slightest amount of pressure. It appears that one of the little curved over retention tabs was broken so that ground was not secure. They were all clean though. I am crimping on a new connector tomorrow and all the contacts are clean now. My guess is that it is the problem. I will post my results tomorrow once I get it all sorted out.
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Road Master
Joined: Aug 2007
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More problems... ugh....
So, after I did the fairing grounds I have been riding the bike. I put at least 500 trouble free miles on it although the voltmeter flops around alot. I checked the battery with the bike running and at idle it shows a constant 12.5v. If I give it some throttle it jumps up to around 13.75 to 14.10 so the charging system seems good.
So... I take it out today and go about 150 miles and everything is great. I get home and decide to go out for coffee. I am riding around town when suddenly my radio starts making some weird popping noises when I apply the front brake. Then... the radio stops responding. I can't turn it off, I can't adjust anything. Its stuck on. Then... the radio makes a fairly loud buzzing noise, the tachometer jumps up to around 8K, the voltmeter drops down to around 2v and the the bike seems like its going to stall. It doesn't stall but the radio goes dark. The bike seems to run fine. I suppose it was a ground issue with the radio. I go directly home and check the bike battery with my fluke meter. Its putting out the correct voltage and running fine. Only the radio is dead so I decide to go back out again.
I get about 5 miles from my house and the dash lights dim, the tach jumps to around 8K and the bike seems like its going to stall again. Again.. it doesn't and clears itself up a second later but I am completely paranoid now so I take the bike home and park it in the garage.
What should I be checking for first? I did all the grounds under the fairing, the battery is good, all the cables are good. This sucks. Its the first time I got my wife out on the bike too!
So... I take it out today and go about 150 miles and everything is great. I get home and decide to go out for coffee. I am riding around town when suddenly my radio starts making some weird popping noises when I apply the front brake. Then... the radio stops responding. I can't turn it off, I can't adjust anything. Its stuck on. Then... the radio makes a fairly loud buzzing noise, the tachometer jumps up to around 8K, the voltmeter drops down to around 2v and the the bike seems like its going to stall. It doesn't stall but the radio goes dark. The bike seems to run fine. I suppose it was a ground issue with the radio. I go directly home and check the bike battery with my fluke meter. Its putting out the correct voltage and running fine. Only the radio is dead so I decide to go back out again.
I get about 5 miles from my house and the dash lights dim, the tach jumps to around 8K and the bike seems like its going to stall again. Again.. it doesn't and clears itself up a second later but I am completely paranoid now so I take the bike home and park it in the garage.
What should I be checking for first? I did all the grounds under the fairing, the battery is good, all the cables are good. This sucks. Its the first time I got my wife out on the bike too!
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Seasoned HDF Member
Joined: Apr 2006
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From: Billings,Mt.
Interesting!
Sounds like the problem got worse by fixing the bad terminals or you just didnt ride the bike long enough before the fix for this new problem to show.
Have you checked all of the grounds?
Have you checked and traced the powered wire for the radio?
Can the anti-dive switch be bypassed to see if that is a problem?
Check all the connectors for corrosion?
Maybe not much help here but sometimes the easy things can get over looked.
Sounds like the problem got worse by fixing the bad terminals or you just didnt ride the bike long enough before the fix for this new problem to show.
Have you checked all of the grounds?
Have you checked and traced the powered wire for the radio?
Can the anti-dive switch be bypassed to see if that is a problem?
Check all the connectors for corrosion?
Maybe not much help here but sometimes the easy things can get over looked.