I wired mine so each is on it's own port. They can connect straight to the EZ-B, no resistor is needed. Between Signal and Ground. Set Digital to turn on and off. Use scripts for sequences i.e. Larson scanner

ok. they are are ok to run off of 5v? And could I wire them all together on one port? e.g. all red visor leds on one port, eyes on another.

The signal wire doesn't supply much current, from memory I think it's 25mA. It's enough to power one and 5V is no problem at all. Powering all 4 would mean each gets 6.25mA which I'd guess isn't enough. You could use a TIP122 circuit.

The headlights either side I tried quickly direct to the EZ-B but nothing happened. It could have been my wiring though but I suspect it was the signal wire not providing enough power. A TIP122 circuit may work but I don't know if 5V is a safe voltage or not.

You may consider a 1k resistor between your 5v output and the LEDs just to knock it down a bit. There also is a adjustable voltage regulator that you can use and just adjust it to the voltage you want. Many of my friends use reastat / variable resistors to cut down current to what they need for the LEDs. Lastly there's the step down converters that work great for this kind of thing too.

Edit - if you want to connect the positive to signal and neg to ground that's fine. The only downside is each led takes up a port. The short leg on a led is the neg, long is positive. https://www.youtube.com/watch?v=XzhVm3WWyy0&feature=youtube_gdata_player

do we know what voltage the leds in the rad are? if so that will help. could I wire 2 leds together? 2 and 2 to do the visor. then use another battery pack and a manual switch for eye/headlight leds?

Replace the LEDs and you may be able to find some that would work together, or juse a TIP122 circuit to power all 4 as mentioned previously. The TIP122 circuit is probably the best option IMO.

Alternately you could build a new circuit for the head using an I2C extender and control everything individually through the I2CWrite commands, using up 0 digital ports.

what is the tip122 circuit?

https://synthiam.com/Community/Questions/3050