Electrical issue

[Phunnybone]

Every once in a while (usually cold) my 85 LTD would flash 16 on the voltmeter (meaning too much charge I think). Yesterday it behaved itself until it completely died - no dash whatsoever, but headlight still modulating (PO had hooked directly to battery with a switch). Poking around, I figured out the 'meter' fused had blown. Hoping to limp home, I replaced that fuse and got it started. But after a couple of miles it died again and I had to use the GWRRA roadside assistance to have it towed home.

I'm thinking its somewhere with the regulator/rectifier (I had tested it earlier and it seemed to test okay. Soldered and shrink-wrapped the wires as the plastic connector had burned out in one place.

For all the electrical wizards - any place I should be looking at besides the reg/rect?

[virgilmobile]

Other than the headlight hard wired and working,is the bike still dead?

[Phunnybone]

Yes. Fuse burned out again. I haven't taken it far enough apart to see, but I did see a puff of smoke in the general area of the reg/rect. I did disconnect the battery when I got it home just in case something was shorting out.

[DaveO430]

Are you sure it was the #4 meter fuse and not the #5 ignition fuse?

[oldishwinger]

Are you sure it was the #4 meter fuse and not the #5 ignition fuse?

yep symptoms seem the same as what I have encountered it was burnt connectors around the starter solenoid and 30amp main fuse

[Rednaxs60]

There are a couple of issues at work here. Fuses 4, 5 and 6 come into play in my mind and the only one that can affect the operation of the bike is fuse #5. This is the fuse that provides power to the engine stop switch, and the sense wire for the regulator. If it fails, the bike will stop – not start. Fuse 4 and 6 does not affect the operation of the bike. To prove this I started my '85 LTD and pulled fuses. Fuse 4 and 6 did not affect the operation of the bike, pulled fuse 5 – bike stops because there is no power to the engine stop switch.

I would also wonder about the headlight modulator, why is it hooked directly to the battery? Is it on a relay that turns it off when the bike is shut down? What is the condition of the battery - have you had it load tested lately?

The other fuses that can affect the operation of the bike are fuse 9 for the CFI system. This fuse gets power from the wire off the battery connection at the starter solenoid. This has an in-line 30 amp dog bone fuse that can be defective – change it, don't just inspect it.

The high voltage reading on the dash voltmeter of 16 VDC is interesting. The regulator has a reference voltage of ~14.2 VDC. If the dash voltmeter is displaying 16 VDC, the sense wire (regulator black wire) is seeing ~12 VDC in the electrical system. The 16 VDC reading displayed on the dash voltmeter represents the reference voltage of 14.2 VDC and the delta between the reference voltage of ~14.2 VDC and the voltage on the sense wire of ~12 VDC; 14.2 plus 2 (14.2-12.2) = ~16 VDC. Straight math. You will have to troubleshoot and determine what is causing this electrical system requirement.

When you get the bike started again, check the voltage at the battery as well, may not be exactly the same as the dash voltmeter but should be close. This will give you an indication of what is happening.

I have been looking into the electrical system on these fuel injected models and find the design to be good but not the best. There is a junction (I call it the power junction) where the regulator output wire (red/white striped) is joined with the red wire from the starter solenoid in the wire harness. This is the main power junction for the electrical system. All current flows through this point to the electrical system be it the battery or the other way to the ignition switch and into the main electrical system. Power does flow towards the battery even after it is replenished back to a 100% state of charge because power is supplied to fuses 9, 10, 11, and a couple of other relays through the wire connected at the starter solenoid battery terminal, not on the battery positive terminal.

This junction is located in the wire harness just below the gas tank fill. Find this junction, connect a sense wire from it to the regulator (disconnect the existing that goes into the wiring harness) and operate the bike. Take readings at this junction, the battery and the original sense wire from the electrical system. The sense wire connected to the power junction should be the closest to the reference voltage of ~14.2 VDC. Turn on various loads to see how the electrical system adjusts to varying loads.

Here is a schematic illustrating this power junction:

I have replaced this junction on my '85 LTD because I removed all the old wiring when I installed the external alternator. Connecting the sense wire at this junction is considered in the auto industry, and our bikes are no different, as a best practice for any wiring upgrade of older model vehicles.

Here is a schematic illustrating connecting the sense wire at this power junction:

Just brain storming here. Good luck. Cheers

[Kurt J]

If your plug was burnt from the regulator to your stator I would check and see if the stator is grounded in the motor. The coils get hot and will ground. When they do it will burn and short at the white plug to the reg. If the stator is grounded then it needs replacing and it my have taken the reg. out with it. If the bike started up and ran for a bit and then died again that would be the battery recharged it self to start again .....good batteries will do that. If anything charge the battery up and start the bike and check the voltage across the battery. It should read 12.5 + at about 2500 rpm. the voltage should go up and down from a idle to a higher rpm. This would mean you charging system is working. If it does not and sits at a low voltage at all times you charging system has a problem.

[Phunnybone]

I would also wonder about the headlight modulator, why is it hooked directly to the battery? Is it on a relay that turns it off when the bike is shut down? What is the condition of the battery - have you had it load tested lately?

The PO had hooked the headlight directly to the battery with an on/off switch. Modulator hooks into the headlight connection.

[Rednaxs60]

I would also wonder about the headlight modulator, why is it hooked directly to the battery? Is it on a relay that turns it off when the bike is shut down? What is the condition of the battery - have you had it load tested lately?

The PO had hooked the headlight directly to the battery with an on/off switch. Modulator hooks into the headlight connection.

Interesting. Can't be doing this type of mod up here, headlight has to be on. Is there something wrong with the OEM headlight switch? I have seen mods where the power to the headlight was through two relays, one for low and one for high. This mod used the OEM switch to trigger the relays when needed. It is intended to provide a better source of power to the headlight for brightness. Not a lot of room for relays in the headlight area on our bikes.

I can understand this because the system is to operate at or as close as possible to ~14.2 VDC. Dropping the voltage to say around ~12 VDC because of wiring-switch losses reduces the brightness of the headlight.

There are a few mods with relays I'd like to try to determine the effectiveness of the mod.

Cheers

[Phunnybone]

I think I found my problem with the electrical death. It was a combination of two things. Dog bone fuse at starter solenoid was in bad shape. The blown fuse issue was caused by a short inside the dash in the circuit board. Figured that out after I grabbed a different solenoid off the parts bike and installed. Replaced the ‘meter’ fuse and it started right up.

Then I noticed there was smoke between the led and the plastic window. Sniff d it and sure enough had that burnt smell.

[DaveO430]

Again proving the smoke theory true.

[Phunnybone]

So much for that idea. Starter solenoid switch from the parts bike worked to get it started. Still running into a short issue with the radio/turn signal and or meter fuse. If I replace the fuses and turn to ACC the radio and voltmeter stay on momentarily until I smell burning and the fuse goes. Don't even have to start it to make it happen.

Any ideas where to start troubleshooting?

[Rednaxs60]

Exactly which fuse is failing - 4, 5 or 6? Trying to get a few thoughts together. If the fuse is failing, and you believe there is a short - what else can it be - I would be taking the wiring harness apart from the fuse block forward. Honda joined a lot of wires together - power and ground - and only used vinyl tape to protect these joins.

It's easy to get at the wiring harness with the front fairing removed.

If the main fuse is failing - #5 - I would be looking at the wiring from the battery forward, especially where the wire from the RR and the starter solenoid join in the wiring harness.

Going to have to get invasive and check the wiring harness.

Cheers

[Phunnybone]

Exactly which fuse is failing - 4, 5 or 6? Trying to get a few thoughts together. If the fuse is failing, and you believe there is a short - what else can it be - I would be taking the wiring harness apart from the fuse block forward. Honda joined a lot of wires together - power and ground - and only used vinyl tape to protect these joins.

It's easy to get at the wiring harness with the front fairing removed.

If the main fuse is failing - #5 - I would be looking at the wiring from the battery forward, especially where the wire from the RR and the starter solenoid join in the wiring harness.

Going to have to get invasive and check the wiring harness.

Cheers

The one that consistently fails is Radio/Turn Signal, although #4 has failed before. It will do this without starting up - just key in ACC position

[Rednaxs60]

Will start to look at the schematics. So the fuse in question is #5. Agree with a short being at issue, but now to find it. Generally not a problem with the item, the wiring yes.

Start in the left front fairing pocket. Good place to start because wiring for the front fairing goes through this space.

Do you have a CB installed? The reason I ask is the space available in the left front fairing pocket is at a premium - everything stuffed into a small area. The radio amp is in there and on mine, I found the wiring to be in need of a good upgrade. Quite easy to ground a wire on one of the components stuffed in there.

If you have a CB installed, you can remove it as well. Make sure you match mark all the leads for reinstall. Not easy to follow the wiring diagram, still have one lead going to nowhere.

Fuse #5 is used to provide power to the travel computer as well. Disconnect it from the circuit to eliminate it as a possibility.

Hope this helps.

Cheers

[Phunnybone]

Will start to look at the schematics. So the fuse in question is #5. Agree with a short being at issue, but now to find it. Generally not a problem with the item, the wiring yes.

Start in the left front fairing pocket. Good place to start because wiring for the front fairing goes through this space.

Do you have a CB installed? The reason I ask is the space available in the left front fairing pocket is at a premium - everything stuffed into a small area. The radio amp is in there and on mine, I found the wiring to be in need of a good upgrade. Quite easy to ground a wire on one of the components stuffed in there.

If you have a CB installed, you can remove it as well. Make sure you match mark all the leads for reinstall. Not easy to follow the wiring diagram, still have one lead going to nowhere.

Fuse #5 is used to provide power to the travel computer as well. Disconnect it from the circuit to eliminate it as a possibility.

Hope this helps.

Cheers

Trip computer was disconnected. The 7.5 amp fuse to the amp was blown too. No CB. The first time it all happened I did see some smoke toward the left side of the fairing and thought it might have been one of my reg/rect wires (but it wasn't). Guess it's time to dig around in the left pocket. It may be one of the wires to the amp as the left side speakers have never worked for me. Thanks for the ideas (I'm not good with wiring diagrams).

[Rednaxs60]

The 7.5 amp fuse powers the travel computer, radio, voltmeter, instrument panel and trunk light switch. First go around more to follow.

Cheers

[Phunnybone]

The 7.5 amp fuse powers the travel computer, radio, voltmeter, instrument panel and trunk light switch. First go around more to follow.

Cheers

I think the short is in the grouping of wires that go through the fairing pocket to the rest of the bike. Still blowing the 7.5 amp fuse, but got the 10 amp in the fuse box to stop blowing after I moved this wires around a little (by no means a permanent solution, but it’ll do for now). Turn signals not working and flashers will stick on (in the dash).