GL1500 tachometer showing higher rpm


Information and questions on GL1500 Goldwings (1988-2000)
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pkund
Posts: 5
Joined: Wed Sep 04, 2013 10:51 am
Location: Canton, Ga.
Motorcycle: 1989 Goldwing 1500

GL1500 tachometer showing higher rpm

Postby pkund » Wed Oct 01, 2014 8:54 pm



Hi all,
I just experienced an issue that some have had in the past with my tach showing high rpm, about 1,000 over. I have checked the relays, by the way I did have the issue with the cover and I just took out the two bolts holding the fuse and relay box in place and removed the whole box, thank god there is enough wire harness to bring the box out of the frame. I tried switching relays, etc. but the problem still persists. One thing I noticed also was that the fuel gauge which usually shows empty around 120 miles, shows a higher reading now, and the temp gauge is showing the motor at a higher temp than usual.
I am wondering if these are related in anyway to the tach issue. I found another ECM module on eBay and will receive it tomorrow, I will try replacing it and see what happens. In the meantime, if anyone has a suggestion I would appreciate any advice.
Just an FYI, for the 1988 1989 models, Honda no longer sells the old type of ECM modules with the multiple pig tails like mine. They do not have a replacement for it either. I tried to locate a new one with no luck. Everyone was out of stock and no ability to order it.
Thanks guys,
Paul



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WingAdmin
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Posts: 17046
Joined: Fri Oct 03, 2008 4:16 pm
Location: Strongsville, OH
Motorcycle: 2000 GL1500 SE
1982 GL1100A Aspencade (sold)
1989 PC800 (wife's!)
1998 XV250 Virago (sold)
2007 Aspen Sentry Trailer

Re: GL1500 tachometer showing higher rpm

Postby WingAdmin » Thu Oct 02, 2014 3:16 pm

pkund wrote:Hi all,
I just experienced an issue that some have had in the past with my tach showing high rpm, about 1,000 over. I have checked the relays, by the way I did have the issue with the cover and I just took out the two bolts holding the fuse and relay box in place and removed the whole box, thank god there is enough wire harness to bring the box out of the frame. I tried switching relays, etc. but the problem still persists. One thing I noticed also was that the fuel gauge which usually shows empty around 120 miles, shows a higher reading now, and the temp gauge is showing the motor at a higher temp than usual.
I am wondering if these are related in anyway to the tach issue. I found another ECM module on eBay and will receive it tomorrow, I will try replacing it and see what happens. In the meantime, if anyone has a suggestion I would appreciate any advice.
Just an FYI, for the 1988 1989 models, Honda no longer sells the old type of ECM modules with the multiple pig tails like mine. They do not have a replacement for it either. I tried to locate a new one with no luck. Everyone was out of stock and no ability to order it.
Thanks guys,
Paul


The temp and fuel gauges run on 12 volts, and the only way to get them to both run high is to have a system bus voltage greater than 13.8 volts - if this is the case, it means your alternator is not regulating voltage correctly. Does this happen when the engine is off (but ignition on) as well - or only when the engine is running? If it only happens when the engine is running, take a voltmeter and measure the voltage on your battery terminals - I'm willing to bet you're seeing too high a voltage.

pkund
Posts: 5
Joined: Wed Sep 04, 2013 10:51 am
Location: Canton, Ga.
Motorcycle: 1989 Goldwing 1500

Re: GL1500 tachometer showing higher rpm

Postby pkund » Thu Oct 02, 2014 4:15 pm

Ok, I rode the bike into work this morning while I was waiting for delivery of the new ECM. As I was riding it in at 65 mph, the tach was redlined at over 6,000 rpm. It was this way the entire hour drive into work. It was chilly around 52 degrees. On the way home this afternoon, temp around 82, the tach showed 4,000 rpm at 75 mph. It was significantly lower this afternoon than this morning. Any clues?

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WingAdmin
Site Admin
Posts: 17046
Joined: Fri Oct 03, 2008 4:16 pm
Location: Strongsville, OH
Motorcycle: 2000 GL1500 SE
1982 GL1100A Aspencade (sold)
1989 PC800 (wife's!)
1998 XV250 Virago (sold)
2007 Aspen Sentry Trailer

Re: GL1500 tachometer showing higher rpm

Postby WingAdmin » Fri Oct 03, 2014 3:07 pm

We really need to get a voltage reading when it's doing this, just to get an idea of what's causing it.

pkund
Posts: 5
Joined: Wed Sep 04, 2013 10:51 am
Location: Canton, Ga.
Motorcycle: 1989 Goldwing 1500

Re: GL1500 tachometer showing higher rpm

Postby pkund » Sun Oct 19, 2014 10:05 pm

Well, mystery solved. As I was riding the past few weeks the tach would act up then go back to normal. This morning again it was cool in the low 50's upper 40's. I started the bike and the tach shot up again. As I was working in the garage I had pulled the bike onto the driveway and it sat there in the sun for several hours. As I started it to put it away the tach acted normal.
This really had me going now. I pulled it into the garage and stripped her down. I took the dash out and I had recently purchased another tach on eBay, just in case. I struggled for an hour to get the dashboard out and the tach out, and low and behold, as I looked at the back of the gauge I saw what appeared to be a leaking capacitor. I am attaching a picture. As you can see the small rust spot on the back as if it were slowly leaking out.
I checked the one I just got and of course it was clean as a whistle. I put everything back together and fired up the bike and the tach is functioning fine now. Since I thought it was affected by the environment I figured the board in the back of the tach had something to do with it.
If everything checks out in the next week or so I'll post with an update.
Hope this helps someone else if they have this issue.
Thanks for your suggestions.
Attachments
Note the rusty spot on the back.
Note the rusty spot on the back.




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