Electrical issues.

[fzstevied]

Can someone please help me. I have a 2002 st1100, i suddenly lost all electrics whilst riding, having done some easy voltage checks I have come to the conclusion my rectifier is fried. I ordered a new one so when it came I decided to fit it. This is where the confusion starts, my service manual states that the rectifier is next to the battery, it shows a 6 pin device so when I take off my side panel to reveal the battery etc I find no rectifier. There is some sort of fuse next to the battery and next to that (to its left) is the starter solenoid. I have had three other people look for the rectifier but it can’t be found. I am convinced the bike requires one but where is it.

 

[bdalameda]

I would check the connector to the master relay with the 30amp fuse on the relay. This is a known troublespot and most electrical issues as you described are related to this connection. Search for Red Wire Bypass on this forum for a lot of info. The relay and connection is under the LH side cover just to the leftt of the battery. There should also be a fuseable link there.

If you have a 2002 ST1100 there is not a separate rectifier, it is part of the alternator. Only pre 1996 St1100 have a separate rectifier.

 

[tnbill]

02 has the 40 amp alternator, the regulator and rectifier is built into the alternator.

 

[STRider]

Does the range of years for your service manual cover 2002?

My direct experience is with a first year, 1991 model, but IIRC the upgrade to the 40amp alternator in 1996 relocated the rectifier into the alternator itself(?)

 

[tnbill]

I would start with the main and other fuses. Not a fan of the red wire bypass the better route is the ignition bypass relay as this removes the load from that curcuit

 

[fzstevied]

02 has the 40 amp alternator, the regulator and rectifier is built into the alternator.

Thanks all, I thought I was going mad. Electrics are not my strongest asset. The fuse at the starter solenoid is 30amp, wouldn’t that be too low for the 40 amp alternator.

 

[Slydynbye]

Simple STuff first check the redwire. Look for a burnt color
This is what it looks like when it is burnt

on this one there is corrosion, What I did was used Solder Flux and heated it to clean the copper, then Soldered the Wire to the connector.

 

[fzstevied]

Thanks, it appears fine just a little dirty. The bike starts and runs with a fully charged battery but it’s only showing 12.6 volts across battery when running and lights don’t fade or brighten with engine speed.

 

[bdalameda]

Thanks all, I thought I was going mad. Electrics are not my strongest asset. The fuse at the starter solenoid is 30amp, wouldn’t that be too low for the 40 amp alternator.

No, 30 amp is correct - the output from the alternator is 40 amp but the fuse is rated for the maximum draw or load.

 

[Slydynbye]

After that you can check under the Bike for the Alternator, make sure the Black/white connector is clean and corrosion free.
Here is a picture of the Alt out of the Bike.

The silver cover is over the Regulator
You MIGHT be able to get to it by removing the 3 screws and the Ground bolt but from what I have heard it is near impossible.

This is with the cover removed


The regulator is a Denso 126000-1160 BUT before doing any of this check all the connectors and grounds

 

[fzstevied]

Ah… I just now need to try and source an alternator I think.

 

[bdalameda]

Thanks, it appears fine just a little dirty. The bike starts and runs with a fully charged battery but it’s only showing 12.6 volts across battery when running and lights don’t fade or brighten with engine speed.

Did you actually remove the connector and look inside? Sometimes the problem cannot be seen unless you take it apart. If all is good there I would then suspect an alternator issue.

 

[Slydynbye]

You may only need the Regulator which is relatively inexpensive

 

[fzstevied]

We all had a good check for any wires that were scorched/burned but nothing seen

 

[Uncle Phil]

Dumb question - Did you check both ends of your battery cables to make sure they were corrosion free and firmly connected?
Also, the ignition switch and the kill switch?

 

[Slydynbye]

Did you actually remove the connector and look inside? Sometimes the problem cannot be seen unless you take it apart. If all is good there I would then suspect an alternator issue.

Agreed, pull the rubber boot up and take the red wire out to inspect fully.

 

[fzstevied]

Dumb question - Did you check both ends of your battery cables to make sure they were corrosion free and firmly connected?
Also, the ignition switch and the kill switch?

Checked all of those.

 

[bdalameda]

It is interesting but in the US we have very few 40 amp alternator issues but in the UK problems are more prevalent. It is probably due to you having many more rainy days riding than we do here. I have heard of far more issues with the windings on 40 amp alternators in the UK. Similarly in the US we have very few rust issues with the ST1100 swing arms and in the UK it is common to find rusted out swingarms.

 

[fzstevied]

Agreed, pull the rubber boot up and take the red wire out to inspect fully.

I will have to check that tomorrow, I have had enough of searching today. Thanks anyway I will update you once I have double checked

 

[fzstevied]

It is interesting but in the US we have very few 40 amp alternator issues but in the UK problems are more prevalent. It is probably due to you having many more rainy days riding than we do here. I have heard of far more issues with the windings on 40 amp alternators in the UK. Similarly in the US we have very few rust issues with the ST1100 swing arms and in the UK it is common to find rusted out swingarms.

That’s the next project I think, the swinging arm and rear shocker they are in need of attention.