Red Wire Bypass or Ignition Relay Bypass

[John OoSTerhuis]

what I did. Fused unswitched power circuits to the headlight relays.

Lee, did you run heavier wire all the way from the battery directly to the relays?

Everything past the fuse is left intact. The mod is only to relocate the headlight fuse's source from a switched hot (the ignition switch) to an unswitched hot (direct from battery).

Larry, how will you do this at/in the OEM fuse box/main buss?
TIA guys

John

 

[dwalby]

Doug, my reading of the colored wiring diagram for non-ABS ST1100s is that battery power runs through the main fuse to the ignition switch which then sends power to the five circuits in the fuse box. Power is then available to the headlights through their relays, which are tripped (hi/lo) by the position of the headlight switch. Both relays are interrupted (headlights off) when the starter switch is engaged.

John

Yeah, I realized I hadn't looked at everything in the wiring diagram before posting that, and looked again and saw the fuse supply current going through the ignition switch. My original post was correct, and the edit: part was wrong. At 8:06AM I removed the edit: part that you quoted and your reply wasn't posted until about 8:30. So you must have started your reply just prior to my removing the edit: part from my post.

 

[John OoSTerhuis]

you must have started your reply just prior to my removing the edit: part from my post.

Yes. Started the post and then spent a bunch of time studying the schematics, especially the start switch interrupt. It’d been many years since I tapped in there to cut power to my HID ballast during a start.

John

 

[Larry Fine]

Larry, how will you do this at/in the OEM fuse box/main buss?

Well, according to my Honda manual's diagram, Fuse C has its own red/black wire that is separate from the red/black wire feeding the other fuses, and the two join together into one wire between the ignition switch and the fuse block.

I intend to find that splice and separate it, extending the Fuse C red/black wire to an always-hot terminal, and leaving the other fuses' red/black feed wire intact. I'll probably use that one new wire to feed everything I add with relay control.

 

[John OoSTerhuis]

You're not. Everything past the fuse is left intact. The mod is only to relocate the headlight fuse's source from a switched hot (the ignition switch) to an unswitched hot (direct from battery).

Looking again... if you leave everything past the fuse intact, that now-switched circuit would also send power to the start switch in the right handlebar switchgear housing = headlights always on. Or did I miss something?
John

 

[Larry Fine]

Looking again... if you leave everything past the fuse intact, that now-switched circuit would also send power to the start switch in the right handlebar switchgear housing = headlights always on. Or did I miss something?

From my post #17:

Since this would also energize the wire that feeds the relays (through the starter and hi-lo switches), and would keep the headlight on, I will also move that wire to the load side of the engine stop switch, so the headlight will extinguish with the engine.

In other words, I will move the black/red wire feeding the headlight-interrupt contacts in the starter switch to the black/white wire leaving the engine-kill switch, so the headlight will not be on when the engine is off. The rest of the lights would still be on.

 

[John OoSTerhuis]

Well, according to my Honda manual's diagram, Fuse C has its own red/black wire that is separate from the red/black wire feeding the other fuses, and the two join together into one wire between the ignition switch and the fuse block

Not in my colored schematic. Power from the battery to the ignition switch (red wire). Then red/black wire to the main fuse buss feeding all five circuits, including the headlights circuit (“C”).

 

[John OoSTerhuis]

From my post #17:

Aha. Yes, I missed that. Sorry.

edit: just looked at the Honda Service Manual’s black and white schematic and see the split in the red/black wire you mentioned. If you get into the harness please show us where/what it looks lIke.

 

[Larry Fine]

Not in my colored schematic. Power from the battery to the ignition switch (red wire). Then red/black wire to the main fuse buss feeding all five circuits, including the headlights circuit (“C”).

If I find they're not separate wires, I can always interrupt and tap in after Fuse C, and use that fuse for another switched load.

 

[kiltman]

In the meantime for those who haven't embarked on this project might I suggest making a red wire jumper. a 6" length of 12g wire with a insulated female spade connector on the end of it and a positap connector. store it with your tool kit or fairing pocket. my experience has that the connector burns out on the road. This is a 10 minute fix with next to no tools. If the connector burns out, break the connector positap the jumper wire higher up on the red wire and plug the spade connector into the main relay and you will be on your way.

 

[Larry Fine]

After looking at the diagram some more, the radiator fan could be directly-powered through a relay, too, as it has its own key-switch terminal. If you trust your battery, it could be wired to run until the T-stat switch is satisfied.

In the meantime for those who haven't embarked on this project might I suggest making a red wire jumper.

Sounds like a good idea. A pic or two of the spots in question would be a nice addition for those less familiar with the wiring.

 

[rwthomas1]

I had never pulled the dubious "red connector" off until today. I found it in surprisingly good condition. No corrosion, no burning, melting, etc. I'm guessing that when Honda designed the bike, the wiring was entirely adequate. Depending on how a bike is stored and maintained determines much of these issues. Even geographic location/climate plays into it. I have reservations tearing something apart that appears to be in perfect condition. I even purchased the parts to do the bypass. I think I will spray the contacts with DeOxit, coat with dielectric and keep an eye on it.

RT

 

[CYYJ]

All you reduced was the current draw of the relays, which isn't much, or am I not understanding your mod?

I replaced the OEM wiring with heavier gauge wiring. I think that is where the improvement in light output came from. I can't recall if I removed the OEM relays or not - it was almost 20 years ago when I did that mod, and the bike is in Africa now, I can't go take a look at it.

Michael

 

[DeanR]

might I suggest making a red wire jumper. a 6" length of 12g wire with a insulated female spade connector on the end of it and a positap connector.

Good idea Robert.

 

[beemerphile]

Lee, did you run heavier wire all the way from the battery directly to the relays?

No I didn't. I simply replaced the switched feed at the fuse box with a battery pigtail. I've often done full replacement with Eastern Beaver kits or the home-made equivalent, but since my plan was to replace the bulbs with LED's I didn't think the upsize in wire was necessary given the lower current draw of the LED bulbs.

 

[Larry Fine]

No I didn't. I simply replaced the switched feed at the fuse box with a battery pigtail.

Am I correct about the headlight fuse having a separate wire feeding it, or is it on the same rail as the other switched fuses?

 

[beemerphile]

Am I correct about the headlight fuse having a separate wire feeding it, or is it on the same rail as the other switched fuses?

They are daisy-chained. You only want to put un-switched power to Fuse C.

 

[Larry Fine]

They are daisy-chained. You only want to put un-switched power to Fuse C.

Correct. My question is what does it take to feed Fuse C separately from the rest of them?

Added: Or, does anyone have a close-up pic of the back of the fuse block? (non-ABS)

 

[beemerphile]

Correct. My question is what does it take to feed Fuse C separately from the rest of them?

Don't remember. Been too long; I'm too old; and uncharacteristically I didn't document it.

 

[jfheath]

Or, does anyone have a close-up pic of the back of the fuse block? (non-ABS)

I have a fuse block chopped out of a wiring harness with leads still attached. I haven't got a clue which model it is from, none of the wiring diagrams in the manual that I have access to match the layout of the fuses. But it is definitely the standard non-ABS model and the wire colours match the colours for all standard models.

There is one red wire in for the clock.

There are 3 red/black wires in: +12V from ignition switch - presumably connected together at some point. Note the bus bar between the top two fuse locations and between the 3rd and 4th fuse locations, so 5 fuses are powered from the ignition switch. The Blue/Brown wire is the fan.



Note that the Honda circuit diagram shows this set up slightly differently. The wires coming out from the fuse box (Right side on the label photo, left side on thr rear view photo) are
Br/Bu (B)
Bl/Br (A)
W/G (E)
Bl (D)
Bl/Bu (G)
R/G (F)
R/Bl (C)






I find it odd that the power for all of these circuits are fed through a single 30A fuse - although when the alternator is running I don't think so much current will pass through it - the red/white alternator cable is connected directly to the red wire on the same side of the fuse.



I wonder if retro-fitting the 40Amp alternator has some part to play in overheating issues ?