Here's a problem for you electricians!

I'm trying to work out what the headlamp switch connections are on a spare switch I have before I go to the hassle of removing my own to hunt for an electrical fault (lack of panel lights) on my 69 Barracuda (It's a mirror image of a USA one).

I've worked out that B1 is from the battery and H goes to the headlamps. B2 is from the tail lamp fuse and R goes to the tail/parking lamps. D is for the dome lamp and P is not used. The slightly cranked tag at the knob end (the manual calls it I but it's unmarked on my spare switch) comes from the wiper on the rheostat disc behind the knob and goes to the instrument panel fuse. But where is the rheostat powered from? Is it (internally) from B1 or B2? Perhaps my spare switch is broken but I don't get any electrical connection (using a circuit tester) between I and either B1 or B2 in any switch position. The wiring diagram in the 1969 manual doesn't show the rheostat

As I can't upload a photo, here's the layout of the tags I'm talking about:


----------- B2--------- D
------------------ H------
----B1------R-----------I

Perhaps somebody out there with a spare unfaulty switch could do a quick test and tell me, or perhaps somebody knows anyway, having been through this process.

Thanks guys.

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1969 Valiant Barracuda (/6 from South Africa, RHD)

D: Dome (interior) lights. Grounds (earths) via the metal body of the switch.

I: Instrument cluster. Feeds from B2 through the rheostat in the headlight switch, through fuse, then to the dashboard lights.

H: Headlamps. Feeds from B1 through the switch's internal circuit breaker, outputs to the high/low beam kickswitch on the floor.

B2: +Feed from the battery, through fuse, to headlamp switch. This is the feed for everything the switch controls except the headlamps.

R: Rear (tail) lamps.

P: Parking lights ("side lights" in UK English)

B1: Power feed for headlamps.


Depending on how and when your car was brought to the UK, the following modification may or may not already have been done one way or another: On (most) pre-1968 US-spec vehicles, the parking lamps (side lights) do not remain lit when you turn on the headlamps. For 1968, this was changed so the parkers stay lit with the headlamps for safety (in case of a headlight burnout you still have at least some visible light on the burned out side of the car). This is easy to retrofit: remove the headlamp switch and unplug its multi-wire connector. Put a short piece of 18ga wire between from the "P" to the "R" terminals on the headlamp switch body, right down at the base of those terminals. Make sure the ends of the jumper are neatly tucked so they won't touch any adjacent terminals. Solder if you like. Then push the connector back onto the switch, on top of your new jumper wire which won't get in the way, and reinstall the headlamp switch. This will emulate the wiring setup of '68 and later cars that keep the parking lamps lit with the headlamps on. Or you can make this connection between the wires that connect to the P and R terminals. If you tap wires, do not use the common fold-over-and-crunch Scotchlok type taps. Posi-Taps are a much better idea. If you'll get an assortment like this, you'll surely find uses for them (they're one of those products that you buy for a particular project, but then other uses for them keep popping up in front of you once you have them):

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Thanks, that was a very lucid explanation.

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1969 Valiant Barracuda (/6 from South Africa, RHD)