Someone, somewhere, asked me for this. I figured I'd post here too.
These are general instructions on how to connect a relay to the KLR 1st-gen "city lights" wires to turn on and off larger devices with the ignition switch.
The quick version:
- Connect the city lights wires to relay contacts 85 and 86. Technically 85 is for ground which is black w/yellow trace on the KLR and 86 is for positive which is brown w/white on the KLR.
- Connect the + wire from the battery (and fuse) to relay contact 30.
- Connect the + wire going to your dashboard or devices to relay contact 87. This contact is normally open (i.e. there's a gap in the circuit). Contact 87 gets power only when the electromagnet is on.
How I do it.
Most of my bikes have a single pair of extra wires from the battery up to the steering head. It's just ring-terminals, a 10A fuse in a sealed holder, and thick wires up to an SAE plug. I can attach whatever I need to that SAE plug by the steering head. The purpose of this fuse is to protect the wires from overheating and catching fire. The fuse at the battery is not intended to protect devices such as GPS.
I put ONLY a single extra ring terminal on each battery contact. Stacking them up gets messy after a while.
For the KLR, I used a pre-wired relay plug. The black and white wires go to the electromagnet, so they are the ones that get plain 1/8" bullet plugs to match the city-lights wires. Both are male because both of the city-lights wires end in females.
The positive wire from the battery (or from the SAE plug) goes to the "common" contact of the relay or 30 on a standard relay. On the pre-wired relay plug that's the blue wire.
The "normally open" contact from the relay powers the switched devices: voltmeter, jacket outlet, and GPS outlet. This is terminal 87 on a standard relay or the yellow wire in the picture. I connect this to red in my wiring. All the quick-connects on this wire are females with insulation covering them completely -- if something comes loose I want to prevent a short-circuit.
You may note a thin wire and disconnect on the blue wire. This was to power a clock that I wanted to remain on all the time.
The green wires from the SAE plug don't go anywhere near the relay. These have disconnects for negtive or ground for all the devices -- switched and unswitched alike.
The big relay above is rated for 30A. The picture below shows one of those plus 2 relays that are each rated for 20A. The small relay with wires has black and red for the electromagnet, yellow for common (to bat), and brown for normally open (to devices you want to turn on when the relay is on).
The small relay with quick-connect terminals is made by Hella, but the numbers are different: 1 and 2 are the electromagnet while 3 is common and 5 is normally open. Looking at the arrangement of the terminals themselves helps identify some of them; 2 terminals oriented together are the electromagnet while the other 3 are for the switch. The common contact is in the middle so you have 50% chance of guessing the normally closed and normally open contacts correctly.
You may notice that the 30A relay with pre-wired plug has a red wire in this pic but no red wire in the picture of my assembled harness. The red wire is "normally closed" -- i.e. it is connected to the battery when the electromagnet is off. I don't need this and it is a potential short-circuit when the bike is off. I removed the wire from the plug. For the smaller relays I would carefully insulate the wire or terminal that gets power when the bike is off.
Notes on wire gauge.
14AWG is fine for 20 amps and if the circuit has only 14AWG and larger wires then the fuse should be 20A. But using 14AWG wire with heated gear, the voltage will drop on that circuit. I have a volt meter and a heated gear outlet at the front of each bike and I want the volt meter to be pretty accurate. Turning on a 6 amp jacket would cause the voltage on that circuit to drop about 5% below what the battery actually has. It would also cause the jacket to get 5% less voltage and be more than 5% cooler. 12AWG will have less voltage drop. With 10AWG it is not an issue at all.
Running heated gear directly from the thin city lights wires would deliver significantly less voltage to the gear.
Notes on other fuse boxes.
There are fuse boxes that let you configure some circuits as always-on and some circuits as switched. If you want to move the stock fuses out from under the seat and move the fan fuse from behind the radiator overflow tank, one of these fuse boxes with 4 or more circuits may be easier to maintain than this extra circuit. I have had no trouble at all with fuses on my KLR so the stock setup works fine with this addition.