While working on my headlamps, I may have inadvertently damaged my headlamp switch by shorting two wires...The cardboard insulator broke in half while trying to press together the original headlamp connectors...@#$!$ Even though the 30 AMP fuse is Ok, the lights won't come on now... While searching for a replacement, is the correct # 1994017 or 1994007?
Thank you...

My 1951 Parts Book has 1994007 as 1939 ALL (a one year switch).

1994017 was replaced by 1995040 in October 1949, fitting lots of vehicles from 1930-38 and 1940-46 skipping 1939.

Hope this helps,

Mike B

Hello Mike,

Thank you very much for the clarification, now I go in search of... Should this switch if found new come with the resistor, GM 817911? Which is probably burnt on mine now... Another question I have is the fuse... Mine is set up with a 30 amp, wonder if it is correct...

Interesting how the "replacing" number has nothing to do with the original switch...[img]http://[/img][img]http://[/img]

More modern switches have a circuit breaker like the center picture, federal regulations, to prevent completely loosing lights with a blown fuse. 30 amps sounds about right.

Part numbers are often superseded as redesigns are made, sometimes to improve reliability or appearance, sometimes for $ reasons.

The resister might be to increase gen voltage when the lights are on, a feature sometimes added to vehicle electrics.

Pretty sure this is all correct.

I understand, so in theory the superseded number (middle photo) could be used if you figure out the wiring... As for other numbers, there is also a GM 1994017 that is identical to the
GM 1994007 which is a one year only switch as pointed out by Mike B... Do you know the exact application of GM 1994017? or is that also a revised number to the original GM 1994007?

Maybe Mike or someone else can answer the part number specifics, I cannot, sorry.

My '62 has a one year rear end, one year axles, one year bearings, not so easy to fix this one year stuff.

Your headlight switch is set up for a voltage cutout, not a voltage regulator. Which do you have? There are four positions on that switch; position 1- off; position 2 for when you have a current draw such as heater and/or radio; position 3-parking lights; position 4 headlights. The more modern switch, of course, does not have that same position 2. And yes, the resistor shown is part of the headlight switch and integral with the voltage cutout system.

Are you sure your switch and resistor are damaged?

My '37 truck came with a 25 amp fuse in it, so your 30 amp fuse should be OK.

Kent

Hello Kent,

You're correct... My truck does not have a voltage regulator and the switch works the way you describe...The resistor is blown out. It happened when I was working with the original headlamp connectors. The insulating gasket split in half causing a short which blew the resistor. If you knew the thickness and type of wire used I suppose it may be repaired?

Still trying to confirm if GM 1994007 is the same as GM 1994017 though...They appear to be identical in every respect.

I can't find anywhere were 1994007 and 1994017 / 1995040 paths ever crossed, so there must be something different between the two. It could be the knob shaft length or the mounting hole diameter in the dash or wiring or ???, but 1994017 /1995040 is not listed for 1939 applications that I can find.

1994017 /1995040 became the "universal" replacement switch for the pre-1939 cars and trucks...

If I have time later I'll dig some more,

Mike B

Hello Mike,

Very interesting indeed, since 1994007 and 1994017 are identical switches... Please see photos. Maybe the differences are any of the possibilities you mention? Still 1994017 and
and 1995040 are completely different switches altogether... Can be confusing.