Red Wire Bypass or Ignition Relay Bypass

[rwthomas1]

Hello,
Reading tech articles and upgrades can be dangerous. I haven't checked the red connector yet, but given the age, I suspect there will be signs of overheating. Then I read Ignition Bypass mod. Hmmm. The RWB seems more needed, lots of failures. The Ignition Relay seems like overkill, also adding several other failure points, and failures don't appear as prevalent in the searches I've done. Additionally, why is there a 70amp relay needed, and then it's wired to a 12gauge wire? The factory wires seem smaller than that as well. I'm not "electrically inclined" but a 70 AMP relay is hugely oversized or the wiring is hugely undersized? Or not? Thoughts?

RT

 

[SMSW]

A couple of points here. First, I don't know exactly what the ignition Bypass is. I've read about it, but never looked closely at what it is or why its needed. As a tired (ok, add re to that) electrician, the relay rating is for the contacts inside. When a motor first starts, it is essentially a dead short so you need robust contacts in the relay to handle the surge. Starter motors draw large amounts of current for a limited time - usually under 5 seconds before the bike fires. Stranded wire will carry large currents before they overheat to the point of insulation failure, and I am reasonably sure the engineers at Honda did their work in sizing the wires.

That said, were it my bike (which is a 1300) rather than doing a bypass, I would try to improve or correct the failure point with better wire terminations, or as you suggested, larger wire and/or a relay with a higher current rating. The point of failure is usually a wire termination - a poorly crimped lug, wire under a screw, etc. because the resistance is higher than that of continuous wire. Toss in moisture, corrosion, and you have a perfect recipe for overheating, oxidation, and damage to the components. The rare reasons wires fail are insulation chafe/damage to insulation from sharp objects, and undersizing for the given load.

 

[jfheath]

Is the 70Amp relay to which you are referring the one that is located just forward of the battery on the left hand side ? It will have a 4 terminal in it all quite low current. 2 of these terminals will be to trigger the relay - ie throw the switch to turn on a massive bit of electrical equipment. That would be the starter motor, and the 2 terminals which provide the power for that are much heavier duty. They need to be. They are behind the 4pin connector and the fuse - clearly visible at the front of the image on the right. There will be two very thick cables connected to those two terminals, one connected directly to the positive terminal of the battery, the other direct to the starter motor.

The fuse in the relay has nothing to do with the power supplied to the starter motor ! It taps into the +12v lead from the battery to provide power for the components on the bike which require power when the ignition is turned off. eg the clock and the radiator fan.


It is 'common' for the 4 low current cables that plug into the 4pin connections to that relay to become corroded inside. That location is prone to getting damp, and unless the cables are well protected, the core inside the insulation can blacken and eventually oxidise. By 'common', I mean that it happened to me once. It was raining hard, I'd been out in it for most of the afternoon, no problems. I stopped the bike outside a shop to call and get something I needed, and when I came out it would not start again. Fortunately the shop was the Honda Dealers. I had no way to get it back home to fix myself, so I just left it with them to sort out. They cut the cable back towards the harness until they found good copper, and spliced in 4 new leads to a new 4 pin connector. I took the removed section back with me to see what had happened.

I am with @SMSW on this. If there is a problem, find the cause of the problem and fix it. If you are uncertain how things work, or you cannot follow the circuit diagrams, then ask the questions.

I don't know what the red wire by-pass is either. I don't want to know !

 

[rwthomas1]

Maybe we are all confused here? The Red Wire Bypass removes the power wire that runs the entire bike, and routes it around the dreaded "red" connector on top of the starter relay. My understanding is that this decreases the load flowing through the terminals on the top of the starter solenoid relay. Less load, less heat, less melting, etc.

The Ignition Bypass uses a 70amp relay to control the entire bike power supply, instead of routing the power through the ignition switch. Said ignition switch is now only actuating the 70amp relay, so reliability should increase? This 70amp relay, and related new wiring is added into the stock harness to correct a deficiency, or perceived deficiency.

Maybe I've got that wrong. The Red Wire Bypass makes sense to me. Removes corrosion prone connections and simplifies the circuit. The Ignition Bypass does not. If there is resistance in that wiring and the switch is failing, bypassing the switch just moves the problem somewhere else. Unless the switch was the problem, and in that case, change the switch! Just trying to understand the purpose of these mods....

RT

 

[kiltman]

There have still been failures with the basic red wire bypass, none with the ignition wire bypass.

 

[CYYJ]

There have still been failures with the basic red wire bypass, none with the ignition wire bypass.

That is true, and your observation is wise. Having said that, though, there's sort of an "80%-20% rule" in effect here - proactively carrying out the red wire bypass before you get a failure that leaves you stuck at the side of the road (like this one: click here) is a good idea - it's a simple modification that doesn't require a lot of disassembly or a lot of electrical skill. It's a one-wire modification.

The ignition wire bypass, as you have noted, is the military-spec modification that will eliminate the other 20% of risk, but it is a complicated modification that requires that the owner have a greater knowledge of electrical theory and a higher level of skill carrying out electrical modifications.

Hence I suggest that the red wire bypass be embodied by all ST 1100 owners. If the owner has the time, skill, tools, and motivation, sure, embody the ignition relay bypass - but don't delay doing the red wire bypass because "someday" you plan to do the ignition wire bypass.

Michael

 

[dwalby]

regarding your question about the 70A relay and 12ga wire. In small runs of a couple feet, 70A@12v is within spec. I suspect the actual current is much less than 70A anyway, so its probably a moot point. Whether there is an actual problem or a perceived problem I can't say, I've owned the same bike for 23 years and haven't found the need to rewire the ignition switch myself.

 

[SMSW]

Question here- suggested by @rwthomas1. The ignition switch activates relays - it doesn't route all the power to the bike through itself. It may be that the 'control' currents routed through the ignition switch are more than the switch can handle, but surely they are not more than 15 amps or so (my guess only). It sounds like the igntion switch bypass simpy uses the ig switch to activate a big relay; it's never a bad idea to use cheap relays to switch power instead of OEM brand specific switches like ignition/handlebar switches, etc. Based on the size of silver alloy contacts that I've seen in Allen Bradley contactors (which typically have a lifespan similar to a well maintained ST), its hard to imagine comparable contact points inside any ignition switch - should it be carrying heavy currents.

I think the problem with the ig switch instead lies more with it's location exposed to rain and moisture. I've wondered for years how bikes can be parked out in the rain with switches and instruments exposed and not suffer the consequences. My wondering has been answered here (my bikes have always been parked under some sort of cover).

 

[John OoSTerhuis]

The ignition switch activates relays - it doesn't route all the power to the bike through itself.

Actually, it does. Well, except for the clock circuit: ST1100 Wiring Diagram

John

 

[SMSW]

Actually, it does. Well, except for the clock circuit: ST1100 Wiring Diagram John

I stand corrected. But how much current does the switch actually see? It activates the a number of relays for high current items (example - headlights) and instruments as well as tail/running lights. I'd like to see some actual measurements of the current flow through the switch. Sure, lean on the horn for 30 seconds because the guy in front of you at a stop light is finishing his text and you might see 15 to 20 amps additional load on the ig switch. Maybe the Honda engineers blew this completely. Since cars' ignition switches have relatively few problems it must be exposure to weather that is doing these bike ig sw's in.

I did see a lot of items' grounds are tied together to one point. No wonder the ground connector goes bad so often.

 

[dwalby]

I stand corrected. But how much current does the switch actually see?

somebody asked about this a few days ago and about 13A is the answer. I measured mine at 12.5A with the key on but bike not running. Starting the bike gets the alternator involved and I'm not sure how that affects the flow through the switch.

 

[Larry Fine]

On my non-ABS '01, despite using relays, the headlight current does indeed flow through the ignition switch, something I intend to change. I plan to rewire the 20a fuse to be fed from an always-hot point, probably through a fusible link from the battery.

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.

This modification alone will remove the single largest load (at least according to fuse size) from flowing through the ignition switch, so I think doing it will help it last longer. I'm also considering doing the same thing for the ignition coils and module.

 

[CYYJ]

...the headlight current does indeed flow through the ignition switch, something I intend to change.

Way back when I first got my 2001 ST 1100, I re-wired it so that the OEM headlight power supplies (both low and high beam) operated relays that connected the headlight bulb wiring harness directly to the main power bus using heavy gauge cable.

You will be pleasantly surprised by the increase in headlight brightness that results from doing this.

Michael

 

[Larry Fine]

Way back when I first got my 2001 ST 1100, I re-wired it so that the OEM headlight power supplies (both low and high beam) operated relays that connected the headlight bulb wiring harness directly to the main power bus using heavy gauge cable.

The ST already uses headlight relays from the factory. You now have relays operating relays.

My intention is to merely re-route the power source pathway around the key-switch.

 

[beemerphile]

The ST already uses headlight relays from the factory. You now have relays operating relays.

My intention is to merely re-route the power source pathway around the key-switch.

That is what I did. Fused unswitched power circuits to the headlight relays. It takes the majority of current (the headlights) off of the switch without an additional relay relay (pizza, pizza!).

 

[dwalby]

That is what I did. Fused unswitched power circuits to the headlight relays. It takes the majority of current (the headlights) off of the switch without an additional relay relay (pizza, pizza!).

edit: removed response because it was wrong, didn't look at the schematic closely enough the first time.

 

[Larry Fine]

I looked at the timing diagram and the headlight current goes directly from fuse to relay already from the factory. All you reduced was the current draw of the relays, which isn't much, or am I not understanding your mod?

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).

Since the headlight relays can only be energized when the key is on, there is no need for the headlight source to be switched, too. ABS bikes are already wired "modded" from the factory.

 

[dwalby]

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).

Since the headlight relays can only be energized when the key is on, there is no need for the headlight source to be switched, too. ABS bikes are already wired "modded" from the factory.

my bad, I looked at the diagram too quickly and missed the part about the headlight fuse being powered through the ignition switch, now I get it.

 

[John OoSTerhuis]

edit: I looked at the wiring diagram and the headlight power goes directly from the fuse to the relays, not the ignition switch, so the bulk of that 13A isn't going through the ignition switch at all. The only thing the ignition switch does for the headlights is energize the relays that power the headlights.

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

 

[rwthomas1]

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).

Since the headlight relays can only be energized when the key is on, there is no need for the headlight source to be switched, too. ABS bikes are already wired "modded" from the factory.

This! Now this makes sense! Remove the load from the Ignition Switch in the simplest way possible. No extra relays. Larry, I don't suppose you wrote this mod up, did you? I figure this should be easy to do. Look for headlight fuse source, cut it and reroute a new supply direct from the battery. If the ABS bikes were this way from the factory, no reason not to do this. Thanks!

RT