Major electrical failure, bike dies whilst riding, completely !

hi, I have the above problem which I cannot find any information on ,whilst riding the bike it shuts of, that's engine and electrics, the ignition key remains on and the dash is completely dead, this is usually preceded by the use of an indicator or putting the side lights/ headlights on, when left for 3 or 4 minutes the relays power up the dash illuminates and she starts normally. I have replaced the ignition relay next to the battery done a visual check of the wiring, my next move is to jump the earth leads at the front of the bike any further ideas would be greatly appreciated, thanks mike

Questions:

28 or 40 amp alternator?
Age and condition of the battery?
Have you tested alternator output?

stretchy said:

I have replaced the ignition relay next to the battery done a visual check of the wiring...

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I'd also give the contact-block of the ignition lock and the mains connectors behind the steering head (underneath air-filter box) a check.

Sounds like you may have a bad ground, start there before replacing anything.

970mike said:

Sounds like you may have a bad ground, start there before replacing anything.

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+1 Trace the battery ground cable, clean all connections, then replace. Do the same with the (+) cable while you are at it.

Is this bike a 1300 or 1100?

woodybelle said:

Is this bike a 1300 or 1100?

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thanks everyone for those replies, its a 2003 1300 ex cop bike, the battery is new and always on an optimate charger. Not sure what alternator is fitted , how would I find that out? with the fitted voltmeter, and the ignition on its 12.5 volts, engine running 13.9 to 14 volts , checked the negative battery to starter motor cable clean and tight. Will try and go through the other checks this weekend, just ridden 20 miles on the bike with no problems clearly an intermittent fault, but I need to find the fault as I cannot trust it on the motorway, thanks again everyone, mike

So is this an official police version or a civilian bike redone as a "cop bike"....either way I'd check all the accessory wiring that was put on for the police radios, lights, etc....maybe remove as much of that wiring as possible....good luck....BTW, all 1300s have the same output alternator, just 1100s had the two sizes..........ff

Seems like something like this was happening recently to another rider and it had something to do with the headlight bulb. Do you have one burnt out?

flyfisher said:

all 1300s have the same output alternator

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2003 to 2007 model years have a 0.742 KW alternator.
Post 2007 model years have a 0.675 KW alternator.

I never understood why they downsized it considering all the electrical demands we increasingly put on modern bikes.

Thanks for the correction, now I know why they finally discontinued the ST

There is a green ground wire in a 24 pin connector under the left middle cowl that has a history of overheating. This ground wire is for the dash area, including the lights. If it is bad it can cause different issues with the cluster and lights. There are many threads on this issue. Since yours sounds like a bad ground issue I would check out that connector first.

I had the same problem several months ago. You can search in the tech section for the whole story if you would like , but the final cure was to run an extra ground wire from the neg terminal on the battery to the frame, and to add an additional ground wire from the frame to the headlight assembly.

I believe that the grounding, particularly on the front of the bike is boderline in the stock configuration. When adding additional loads such as upgraded headlight bulbs, heated grips, GPS ect there is enough power to run them but may not be enough ground capacity.

I may be wrong in my simpleminded electrical theory, but in practice, the additional grounding solved the issue immediately and permanently.

Good luck

Here: https://www.st-owners.com/forums/showthread.php?108777-Cranks-No-Start-Lights-stay-on-when-switch-is-turned-off&p=1379606&highlight=ground#post1379606

Andrew Shadow said:

2003 to 2007 model years have a 0.742 KW alternator.
Post 2007 model years have a 0.675 KW alternator.

I never understood why they downsized it considering all the electrical demands we increasingly put on modern bikes.

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They didn't downsize the alternator, just the published capacity.
31100-MCS-003, same part number for every ST1300, even the ABS and police models.

Could be a short or grounding issue. Try starting here.

Gents , thanks again for all your replies, i ve got plenty to look at, interestingly I did replace the n/s H4 headlight connector 2 months ago as the original had melted, I will be starting with the earth connectors and positive feed to the starter relay, and fitting new earth cables, keep you posted, cheers mike

stretchy said:

Gents , thanks again for all your replies, i ve got plenty to look at, interestingly I did replace the n/s H4 headlight connector 2 months ago as the original had melted, I will be starting with the earth connectors and positive feed to the starter relay, and fitting new earth cables, keep you posted, cheers mike

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Gents, problem now sorted !, hopefully, I firstly took all the plastics off including the headlight cowling I ran extra earth wires from both headlights to separate earth bolts on the front frame, I then ran a wire from the yellow earth block to the frame, then ran a wire from the earth on the 24 pin ( although mine is a 26 pin? ) directly to the negative on the battery, I connected up the electrics and ..............the fault was still there and now it was permanent, I then re checked the wiring loom starting at the front, and was able to cause the fault by moving the cable that comes from the ignition cylinder and twists underneath the brake pipe I re routed it having seen a thread describing chafed wiring at this point .On close examination of the 4 pin clear connector block the spade connector looked fine, but green corrosion was evident within the connector on the solid red wire, I replaced it , problem solved I have used the bike all week. The group of connectors clearly don't have enough protection from the elements I intend to strip them all down re grease and use lengths of bicycle inner tube and cable ties either end to fully waterproof them. Thanks again for everyones help, hope this thread assists someone in the future,
cheers mike

Glad you were able to resolve your issue.

Nicely done! One of the first things I did when I started installing a lot of electrical accessories was to install a good central grounding block. No issues on the electrical side of the house.

John