LED Headlight Conversion with Atari?

Thinking of trying one of the H4 LED conversion bulbs from Superbright LEDs. For my tail and brake lamps, when I converted them to LED, I had to replace resistors with Schottky rectifiers in the Atari to get proper voltage drops so it wouldn't complain. Anyone know whether the lower draw of this LED bulb (it's about 19W) is low enough to cause the headlamp warning circuit to trip?

Also, anyone tried this bulb? If so, how well did it work out?

 

The reed relays internal to the CMS are set to trip at 1 amp, so the 19W bulb would consume enough current to trip them.

However, there is also a filament check done by the CMS, so you would still get the "HEAD" warning as the LED bulb would not provide the low resistance path to ground on the non active side.

If you want to keep the warning active (at least partially) the filament check must be disabled and the "HEAD" warning will only appear if the active side is not illuminating. To disable the filament check you have to add a resistor and do a bit of rewiring because of the way the high beam indicator bulb is wired to utilize the headlight low beam filament as the return path. Adding the resistor is easy on the Maxim and Turbo as they already have wires and bullet connectors at the H4 connector, not so easy on the Seca which does not have the wires. Two resistors are required if you are running an LED indicator bulb in the high beam indicator.

This is what I currently have wired and have been running with for about a year:

 

Thanks for this. Interesting setup.

I'll have to think about this a bit. Seems like the best circuit would be one does its own forward current check on the HB and LB connections when there is not 12V supplied to either reed relay, and pulls the base of Q1 low under these circumstances... going high impedance otherwise. At that point, the two diodes could also be removed, since they would be superfluous.