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 Post subject: LED 1156&1157 Bulb Installation
PostPosted: Mon Feb 08, 2016 5:52 pm 
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Joined: Mon Jan 11, 2016 7:19 pm
Posts: 15
Location: Rest place in San Diego County
At three score and ten my mitochrondia have slowed down so I need some external heat to keep my body warm and hands flexible. At 90W total for heated vest and grips (see the Aerostich Heated Vest Installation and BikeMaster Heated Grips Installation topics) I needed to buy back some power to compensate for the P800's awesomely weak alternator ([email protected] is about what my 1969 CB750 put out). The big drain being the headlight I replaced the 4840cp 100W/80W incandescent bulb that came with the motorcycle with a 3800 lumen 20W/40W LED bulb from Cyclops Adventure Sports (see LED H4 Headlight Bulb Installation). The next big drain I could address was the six 1156/1157 incandescent bulbs going from 7/27W to fraction of a watt).

This installation is only for 1990 and 1994-1996 motorcycles with self-cancelling turn signals; I can't speak to 1989 and 1997-1998 motorcycles.

I replaced all the 1156 and 1157 incandescent bulbs with 45 SMD 1156/1157 tower BA15S retrofit LED bulbs $15 each from SuperBrightLeds as follows (quantity 2 each):

Turn/Park: Amber 1157 12/70 lumens (clear incandescent is 3/32cp*)
Brake/Tail: Red 1157 12/85 lumens (clear incandescent is 3/32cp*)
Rear Turn: Amber 1156 110 lumens (clear incandescent is 32cp*)

* per webBikeWorld Bulb Brightness Comparison 3/32 cp is 38/402 lumens; note caveats on cp<=>lumens conversion which is not direct because they measure different things

LED Cool White bulbs are 55/220 lumens so you might want to choose them for extra brightness.
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Changing the turn/park, brake/tail and rear turn bulbs to LEDs is a straight-forward bulb replacement. Apply a bit of silicone grease on the rubber socket seal to improve weather-tightness.

I also replaced the license plate bulb using an extra 194 LED I had laying around. The bulb is polarity-sensitive so turn the ignition on and see if it illuminates. If not, pull the bulb out, rotate it 180 degrees and push it back in.

You will need an LED-capable flasher relay to preserve the standard flash rate. I used the 3-lug Black Japanese-vehicle LED Bulb Electronic Flasher $13 from SuperBrightLeds.
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You want to do this while you have the bodywork off to replace the headlight bulb.

Facing the motorcycle head-on, you will see on your right a black rubber band about 1/2" wide and 1/16" thick. This is the rubber mount for the Turn Signal (aka Flasher) Relay (TSR). Taking a long straight-blade screwdriver gently ease the band off the metal post. Take the band and relay together -- don't pull the relay out separately. I didn't take a Before picture so here is the After.
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Then pushing in the clip retainer remove the 3-pin connector without breaking it. I needed three hands to do this. Save the relay as a souvenir -- you can have mine for the cost of postage.
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Some people make a harness to mate the Honda connector to the LED TSR. That's not me -- I cut the connector off because I'm never going back to incandescent bulbs and the motorcycle's next owner will buy it from my guardian or executor. I used 0.25" insulated spade lugs as follows:

Black/Brown -> B terminal (B is shorthand for Battery +)
Blue/Black -> E terminal (E is shorthand for Earth, aka Ground, Battery -)
Gray -> L terminal (L is shorthand for Load)
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Put some silicone grease on the terminals and tie-wrap it, with terminals facing down for moisture drainage, close to where the Honda TSR was (see After picture above).

Rating: 4 stars -- should do (power savings for heated vest and grips, improve visibility)!

Postscript: The Position (Parking) Light Relay

Twenty years ago my motorcycle was a BMW K100 which had self-cancelling turn signals. The K100 used a return-to-center switch to initiate turn signalling with electronics handling the sustainment and termination functions. I was confused when I examined the PC800 wiring diagram because Honda uses a combination of a mechanically-latching switch to perform the initiation and sustainment functions with the Cancel Unit (CU) electronics used for the termination function.

Based on an examination of the Honda wiring diagram, I believe no low parking light or high turn signal currents flow through the CU. If you initiate a left or right turn signal, the switch mechanically latches into place which sustains turn signalling until terminated by the CU. The turn signal switch remains mechanically latched in the signalling position but the turn signal trons ain't flowing through the TLR anymore because the CU opened it's Earth (ground) circuit.

The TSR flows high currents via the turn signal switch for the turn signal filaments and the PLR flows low currents via the turn signal switch for the parking light filaments. The PLR is used to extinguish the same-side parking light filament when the turn signal filament is illuminated, apparently to provide a better park/turn separation (this doesn't work for "single filament" 1157 LED bulbs where Park is dim illumination of all SMDs and Turn is full illumination of all SMDs). When turn signalling is terminated by the CU by opening the PLR's ground circuit, the PLR restores the parking light circuit for the bulb at the turn signal position (eg, if the turn signal switch is latched left then the PLR supplies power to the left parking light).

I believe with Honda's turn signal switch handling both high-power turn signal currents and low-power parking light currents, under some conditions those currents get transiently mixed by the switch (ie, a wiper bridging two contacts while moving from one position to another) in a manner that doesn't affect incandescent bulbs but does affect some LED bulbs resulting in damage to the PLR. And I think these conditions are affected by wear patterns in the turn signal switch. But that's my analysis; I don't have data to support it.

So far my PLR is working properly with the 1157 LED bulbs. Here's how I'd replace it if it stops working. Facing the motorcycle head-on, you will see on your left a black rubber band about 1/2" wide and 1/16" thick (Blue tape marks location). This is the rubber mount for the PLR. Taking a long straight-blade screwdriver gently ease the band off the metal post. Take the band and relay together -- don't pull the relay out separately.
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Then pushing in the clip retainer remove the 4-pin connector without breaking it. I needed three hands to do this. Save the relay as a souvenir.
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Cut the connector off and use 0.25" spade connectors with an SAE SPDT relay as follows:

Black/Brown -> 86 terminal (B)
Blue/Black -> 85 terminal (E)
LightBlue/White -> 30 terminal (common, to right-hand parking bulb)
Orange/White -> 87a terminal (normally-open, to left-hand parking bulb)

Put some silicone grease on the terminals and tie-wrap it, with terminals facing down for moisture drainage, close to where the Honda PLR was.

Note: if you simply remove the PLR then the mechanically-latching turn signal switch will not restore the same-side parking light until you physically move the switch to center position.

_________________
Purple 1989 Mustang for fun
Yellow 1996 PC800 for more fun


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