85 LTD Electrical - need guru


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Phunnybone
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85 LTD Electrical - need guru

Post by Phunnybone » Thu Feb 22, 2018 4:09 pm



Bike keeps blowing the 7.5 amp fuse in the left pocket (trip computer and a few other things). Doesn't even have to be running for this to happen. When started, voltage looks normal on the meter but then will climb to 16.0 and flash.

Where do I start?



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virgilmobile
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Re: 85 LTD Electrical - need guru

Post by virgilmobile » Thu Feb 22, 2018 4:29 pm

Can you tell what you have tried so far?
A quick look shows that the 7.5 amp fuse feeds the instrument cluster,trip computer and trunk light.
Because it just blows by itself,I am guessing that it is the memory backup circuit.
I will suggest stop blowing fuses..that's not finding the problem..Take a old light...preferably a headlight...it can handle some power...a small test light won't work..Attach it in place of the fuse...As the short exists the light will simply light up.As you disconnect the parts attached to that fuse something will kill the short..This will separate where the short exists...
You may try different lights but if a 7.5 amp fuse is blowing,that's over a 80watt draw.Thus the reason to use a 50 watt headlight lamp.
It will get hot too.
Do you know where the plugs are to disconnect to isolate the problem?

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Phunnybone
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Re: 85 LTD Electrical - need guru

Post by Phunnybone » Thu Feb 22, 2018 4:47 pm

Thanks Virgil. Issue started a couple of weeks ago. Was riding and dash went out, blew the 10amp meter (#4) fuse and the radio/turn signal fuse (#6). Got it started again without dash then it died hard and had to use the GWRRA towing service (glad I paid for that). Dogbone fried at starter solenoid so I swapped out with parts bike (I'll replace with fused version later). Started looking for shorted wire - haven't found anything yet. Did narrow down to somewhere in the left pocket (I think - thats where the burning smell comes from right before fuse blows). I'll do a quick swap with a spare trip computer in case it's something in there. The only thing I worry about using a light in place of the fuse is melting more wires if that's the cause. While I can't see anything, I did a 'jiggle' test on the wiring leading out of the left fairing pocket to the main chassis. That stopped the blowing of the normal fuses (if I switched to 'on' the voltmeter would start a downward march until a fuse blew - now it doesn't but will end up reading 16.0 and flashing). Turn signals are DOA and when flasher pushed in both flasher lights stay on in the dash, but no flashing.

That's about all the troubleshooting I've been able to do so far.

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virgilmobile
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Re: 85 LTD Electrical - need guru

Post by virgilmobile » Thu Feb 22, 2018 5:15 pm

Using a light instead of a fuse is ideal.It can't burn wiring.All the energy is dissapate in the light and it's easy to tell when the short is removed...the light simply goes out.

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Phunnybone
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Re: 85 LTD Electrical - need guru

Post by Phunnybone » Thu Feb 22, 2018 5:17 pm

On a whim, I swapped out the trip computer. Fuse not burning out any more. Radio and turn signal/flashers still not working though. When I hit the flasher button, both lights stay on in the dash and the voltmeter starts to go back down. Will be looking at the signal/flasher wiring tomorrow.

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Re: 85 LTD Electrical - need guru

Post by DaveO430 » Thu Feb 22, 2018 6:08 pm

On the high voltage problem it may not be getting a good reference voltage on the black wire to the regulator or the regulator is not grounded good.

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Re: 85 LTD Electrical - need guru

Post by Phunnybone » Thu Feb 22, 2018 6:19 pm

DaveO430 wrote:
Thu Feb 22, 2018 6:08 pm
On the high voltage problem it may not be getting a good reference voltage on the black wire to the regulator or the regulator is not grounded good.
How can I fix that? I have a feeling that the high voltage caused the other issues

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Re: 85 LTD Electrical - need guru

Post by Rednaxs60 » Thu Feb 22, 2018 7:16 pm

Phunnybone wrote:
Thu Feb 22, 2018 6:19 pm
DaveO430 wrote:
Thu Feb 22, 2018 6:08 pm
On the high voltage problem it may not be getting a good reference voltage on the black wire to the regulator or the regulator is not grounded good.
How can I fix that? I have a feeling that the high voltage caused the other issues
You can run a sense wire to the battery terminal of the starter solenoid, but recommend using a relay for this. Recommend the battery terminal of the starter solenoid as the electrical system voltage will/should fluctuate more here than at the battery positive terminal, and be a truer representation of what is happening in the electrical system.

The switched relay turns the power on/off to the RR the same way that the OEM has wired the sense wire after the ignition switch, power to the RR sense wire only when the key is on. The OEMs used to connect the sense wire to the battery, but changed this after having some issues with connections. This site is a good read on this: http://www.electrosport.com/technical-r ... stem-works

A better location for the sense wire, IMHO, is at the junction where the red/white wire from the RR is joined to the red wire to the ignition switch in the wiring harness. This schematic shows how the wiring is connected:


This junction is in the wiring harness about midway between the RR and battery just below the fuel tank fill.

Would still need a relay to have the power on the sense wire turned on/off. The reason I mention this is that the voltage at the battery is relatively constant after the engine has been started, and the battery topped back up and has a 100% state of charge of about 12.6 VDC. Since the electrical system operates at ~14 VDC the battery never discharges any power until the voltage in the system drops below battery voltage; however, the electrical system voltage does fluctuate and as such, the electrical system voltage that the RR senses should be the electrical system voltage and not the battery voltage. This is even more important on these FI bikes.

There is current flow through the wiring to the starter solenoid for our bikes, besides the trickle charge to the battery, because of the connection for the main relay, and others at the starter solenoid battery terminal. If this was not the case, the current flow through the wiring to the starter solenoid would be approximately 1 to 2 VDC depending on the condition of the battery, all other power generated would be going to the electrical system to operate the bike.

A second reason to connect the sense wire at this junction is that the sense wire location after the ignition switch is on a circuit that provides power to various other electrical components, and the voltage drop being sensed is less than ~14 VDC, say 2 VDC less for an example. If this is the case, the RR is designed to output power to maintain ~14 VDC. If the sense wire is 2 VDC less the RR will try to compensate and output 16 VDC (14 + 2) until the system comes back to ~14 VDC. Since this will probably never happen, the RR will continually let more power into the system than required continually.

You will see the voltage drop when you use the signals with the engine at an idle. It happens with mine and I have a 55 amp alternator that registers 14.1 VDC at idle - fluctuates between 13.6 and 13.7 VDC. Does not fluctuate when at speed with the signal turned on. This has also been reported by other forum members. My experience to date.

Just my thoughts on the issue. Good luck.

Cheers
"When you write the story of your life, don't let anyone else hold the pen"

Ernest

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Phunnybone
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Re: 85 LTD Electrical - need guru

Post by Phunnybone » Fri Feb 23, 2018 7:35 pm

Flashers work after replacing flasher relay, but turn signals still not working. Charging system seems to have settled down for now.

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Re: 85 LTD Electrical - need guru

Post by Rednaxs60 » Fri Feb 23, 2018 11:08 pm

Have the same type of issue on mine here in Victoria. I put a 2 prong electronic flasher in for the turn signals because I had replaced the signal lights with LED bulbs. Found the issue was a bad connection at the rear signal light. Went to put the original flasher in and the signals did nor work, but the 4 ways did. Have left the 2 prong flasher in and the signals work fine, but do not self cancel. Working on this. Replaced the relay under the coils, no joy either. Checked the signal at the 6 pin connector up forward left side of steering stem down low, syill no joy. More investigation needed.

As an aside, got me an AC/DC current clamp meter and checked the current on the bike this afternoon.

At start and idle 14.0 VDC showing on the dash voltmeter, driving lights off, 17 amps. Drops to 15.5 amps after battery topped up.
At idle 1150 and 14.0 VDC showing on dash voltmeter (still cold and fast idle on) with 2 sets of driving lights - 20.5 amps
At idle 1150 and 14.0 VDC showing on the dash voltmeter (still cold and fast idle on) with 2 sets of driving lights and rad fan on (have a manual on switch) - 23.5 amps

Signals make the amperage fluctuate, but this is only short term. Will check current going to the starter solenoid because of the 30 amp circuit connected to the starter solenoid battery terminal - interesting to see what goes through there.

Don't expect the readings to change much. Interesting results, and I have an external alternator installed.

Cheers
"When you write the story of your life, don't let anyone else hold the pen"

Ernest

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Phunnybone
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Re: 85 LTD Electrical - need guru

Post by Phunnybone » Sat Feb 24, 2018 7:37 pm

Sold it - will continue with getting my original one back on the road. I'm betting the wiring in the trunk was to blame for the turn signals not working and the flashers working. Could barely see the trunk lights.



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