starter relay wires getting hot

robbo156

Joined
Oct 22, 2009
Messages
4
Location
nottingham uk
Bike
1991 st1100
The wires from my starter relay are getting really hot. I have put a new relay onbut still have the same problem,she still starts and runs ok , can any of you guys steer me in the right direction. :confused:
 
Do you mean the little wires that trigger it or the big ones that transfer power to the starter?

--Mark
 
I would take a close look at the wires/connections to make sure they are not corroded. I was having issues with my fuseblock relay getting so hot it was melting. Turned out that the wire connections had gone bad, causing the heat.
 
The circuit that engages the starter relay should only be energized when you're pressing the starter button, so there shouldn't be any occasion for the wiring to get warm, much less hot.

I'd start by turning on the ignition and looking for voltage across the relay coil. Maybe your starter button is sticking in some position that's allowing current through but has enough resistance that the voltage drop is enough to prevent the relay from engaging.

--Mark
 
Check and clean the wire contacts... the wires should be larger enough for the relay from factory, heat usu means more resistance.
 
Hi Rob. My guess is it's not the relay wires, but is the main fuse (red) lead. You might want to do the bypass mod just for peace of mind. Wait too long and you might end up like this:



Amazingly, this ST was still running this way, but wouldn't have lasted for very much longer. I cleaned it up for my friend and did the bypass.

Regards, John :STOC:
 
John OoSTerhuis said:
Hi Rob. My guess is it's not the relay wires, but is the main fuse (red) lead. You might want to do the bypass mod just for peace of mind. Wait too long and you might end up like this:



Amazingly, this ST was still running this way, but wouldn't have lasted for very much longer. I cleaned it up for my friend and did the bypass.

Regards, John :STOC:
Click to expand...

hi john, it did, the relay had started to melt but the connector is still ok so you recommend the bypass ? thanks paul
 
I would clean all the connections, replace the starter relay AND clean the starter switch fully and apply some dielectric grease.

Cover all eventualities and you should be okay. You may have to replace the connector to the relay also and lengthen the wires that go to it.
This had been done on my previous ST, but re-occurred, which as far as I could make out, was due to the starter button/switch getting dirty.... this caused improper operation of the starter relay due to lower current through the energising coil, this leads to drop out of the relay when the starter engages as the relay energising coil terminal voltage drops even further.... heat builds up in the relay and voila, relay overheats.... I think the battery suffers as well due to rapid transitioning on and off load as the relay chatters.....

Well that's my take on it anyway....
 
Can't find it just now (lots of old discussions about the bypass on ST-Riders.net, but in the members only area), but it's pretty simple - remove the red wire from the 4-P, cut it back until you get good wire (flexible/not stiff, no corrosion) and splice on a heavy duty inline fuse holder (30amp) and connect its other end to the battery + post.

Colored wiring diagrams here: http://www.st-riders.net/index.php?topic=3908.0
 
Firstpeke said:
I would clean all the connections, replace the starter relay AND clean the starter switch fully and apply some dielectric grease.

Cover all eventualities and you should be okay. You may have to replace the connector to the relay also and lengthen the wires that go to it.
This had been done on my previous ST, but re-occurred, which as far as I could make out, was due to the starter button/switch getting dirty.... this caused improper operation of the starter relay due to lower current through the energising coil, this leads to drop out of the relay when the starter engages as the relay energising coil terminal voltage drops even further.... heat builds up in the relay and voila, relay overheats.... I think the battery suffers as well due to rapid transitioning on and off load as the relay chatters.....

Well that's my take on it anyway....
Click to expand...

thanks for your input guys the work begins tonight :)
 
Rossi said:
I think this is it John. It's labelled as "Main Fuse Upgrade".

http://www.st-riders.net/index.php?topic=3923.0
Click to expand...

Aha... it WAS in the ST1100 Archive Of Wisdom! Thanks, Julien. I didn't use the right search word(s). Rob connected his to the 96-02 OEM 55amp fuseable-link/fuseblock that he installed when he upgraded to the 40amper. With a 28amper I'd go direct to the battery.

N.B. - Also, looking at the 28amper's wiring diagram, the red-w/white-stripe wire at the red 4P is still needed by the VRR and still requires fuse protection. It can either continue to use the 30A main fuse in the starter-relay/main-fuse unit (assuming it's still functional), OR it can also be snipped and spliced into the new inline fuse holder along with the red wire.

John
 
Last edited:
John OoSTerhuis said:
N.B. - Also, looking at the 28amper's wiring diagram, the red-w/white-stripe wire at the red 4P is still needed by the VRR and still requires fuse protection. It can either continue to use the 30A main fuse in the starter-relay/main-fuse unit (assuming it's still functional), OR it can also be snipped and spliced into the new inline fuse holder along with the red wire.

John
Click to expand...

Hi.
I am on my my way to do the red wire Bypass.
I am not sure what to do with the red/white wire from the VRR.
When i look on the electric scheme, i think this red/white wire must carry the same current (Charging current + load current ) as the big red wire ?
In my mind, both the red and the red/white wire must be included in the bypass.
Should i then splice it into the new inline fuse as mentioned above, or get another inline fuse ?

Please let me have some comments on this.:)

Kairo
 
John OoSTerhuis said:
N.B. - Also, looking at the 28amper's wiring diagram, the red-w/white-stripe wire at the red 4P is still needed by the VRR and still requires fuse protection. It can either continue to use the 30A main fuse in the starter-relay/main-fuse unit (assuming it's still functional), OR it can also be snipped and spliced into the new inline fuse holder along with the red wire.
Click to expand...

Kairo said:
Should i then splice it into the new inline fuse as mentioned above, or get another inline fuse ?
Click to expand...

Kairo,
Yes, you should splice.

Mark
 
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