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TLOTM Sept. '08
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Discussion Starter · #1 ·
I bought & installed flash2pass garage door opener system
(Great system incidentally - no more carrying remote and fumbling for it when returning - installed transmitters on all three bikes and one car to get rid of the visor clip-on)

The other bikes worked great - what I found on the TL however was that it wasn't working off the passing switch - that had me confused initially. The wires were clearly hooked up to the high beam and ground return, I could see the light flashing on my garage wall, and the transmitter and garage door opener would work if I flipped the Hi/Lo switch instead of using the passing switch. :confused

Then I noticed the difference was that when on Low Beam, and you use passing switch, the low remains on when you close the passing switch
i.e. Both beams are on simultaneously.
OK - maybe battery sagging a little with all that load I thought; so started bike and tried again - same problem, running engine made no difference.

Time to break out the meter!
I checked at the connection for the f2P and shocked to find dropped into 9's when main beam (with flash) plus low on!! Then with just main beam was still only in low 10's
First thought was my battery was knackered so I checked at the battery itself - still over 12 volts with lights on.
Shoot! Dropping over 2V to the lights!
I started chasing the wiring through the starter relay, igntion switch, left bar switch loop (through my headlight cut relay) and over to left bar switch adn on to fuse panel and to lights. Actually dropping all along the way - probably biggest through the left bar switch. All my connector plugs were clean and free of oxidation - this is all down to the thin gauge wiring on this circuit. You're actually pulling 240W of power (almost 20 amps) through that circuit - including the switch itself! Way too much for these skinny little wires!

Note that this has nothing to do with the FLash2Pass - that was merely the catalyst that got me looking into this. Honestly, I never liked that the power was all being routed directly through the switches etc, Just one of those things 'you'll get around to ..........'

Decided it was long overdue to install headlight relays.
The easiest way to go about this is to remove the headlight/instrument harness completely, then you can work on your bench. Not a big job to remove that.
Essentially I took the drive for each relay directly off the headlight plug wires using the Hi/Ground off one light's wires and Lo/Ground off the other, to drive a separate relay for the Hi & Lo circuits. So those wires are directly connected to the new relays' coils. I cut the headight plugs off up close and then untpaed the wires to connect directly to the relays.
I then ran a common power line to both new relays with 12 ga fused feed directly from battery; next made 14 ga mini-harnesses with twin wires at the relays, going to each headlight plug. The 14 ga wires were soldered directly to the pins in the headlight plugs. (You can pop the terminals out of the plugs by unlocking the latch)
As part of the new mini-harness, I also ran new 14 ga ground wire from each plug, terminated to a common 12 ga wire directly from battery. You can install a mini-plug on the 12V & ground feeds here at the steering head, if you wish to be able to still remove the lighting harness later. I opted to hard wire mine all way back to battery - eliminate the additional connector. I figure if it needs to come off down the road, I'll cut wires and add connector at that time! :devious

Another consideration you can include, if you haven't already, is to add a starter headlight-cut relay. This will remove power from lights during starting, giving max power available to coils and starter for improved starting.
Previously, I showed how to wire this on the 'power' side of the lights on a variation of SteveTLS original idea :
You can do this while you're in there, similarly interrupting the power before it goes to the headlight switch.
Or while you are wiring the new ground returns for the headlight plugs, interrupt the ground return with the cut-relay instead.

The Results:

Battery Power Only

Across Battery terminals 12.6V
With ignition on - 12.25V

Measured at output of Lo Beam Relay - 12.02V
Press 'flash' for high beams (low beams also on) - 11.75V.

Engine running

Across Battery terminals 14.15V (FH012 Regulator)

Measured at output of Lo Beam Relay - 13.98V
Press 'flash' for high beams (low beams also still on) - 13.75V.

High beam or Low beam both running at 13.98V
Only with both (240W does iy drop another 0.25V

SO VERY conclusive! I picked up ..more than 2V!!!!
Oh - flash2pass works as intended now! :devious


Here's overall diagram incorporating the headlight cut option as well as the headlight relays.

Unfortunately pics are nothing special to look at - I should have taken pic of the harness when it was all assembled, before re-installing back on the bike.


For those of you who want the simple route, you can puchase a ready-to install kit from Eastern Beaver.
With that kit, simply unplug the headlight connectors, plug one of those into the mating connector on the harness, connect to the battery and plug new light connectors on the lamps.

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