71 rallye cluster wiring question

I’m in the process of converting my 71 Satellite’s gauges from standard to rallye cluster and I need a little info. How many wires and what color are the wires that go into the brake warning lamp socket? I have the wiring diagrams for both clusters plus a spare wiring harness that has been converted also but it’s a bit hacked up. Converting my non-rallye harness isn’t too bad but this one item isn’t consistent between the two harnesses. All the other sockets have just one wire but from what I can tell from the diagram the brake warning lamp should have two. If the socket is different from the rest a picture would be nice also. Thanks!

Have you tried the roadrunnernest, Joel?

I poked around on that site but didn't find anything. I'm not a member there. I'm sure someone here will have the help I need plus I bet most of the members of that site are on here too. Thanks for the suggestion.

I have the FSM at work.

It looks like there are 2 wires:

A dark Blue wire from post #23 on the bulkhead goes to the lamp that goes to the field side of the voltage reg.

There is also a black wire that is listed as the dual brake system ground that goes to post 12 on the bulkhead and then to the brake lamp warning switch on the prop valve.

My interpretation is that power is suplied through the ignition system and the black wire provides the ground when the warning switch is thrown.

the same setup is for the standard dash except the standard dash wiring is provided with a larger circular socket thingie. On the FSM the black (ground) wire comes from the B post (7 o'clock position) on the round thingie and the blue (power) wire comes from the A post (6 o'clock position).

I would assume that if you at least get the black brake switch ground wire correct a supply from any accesory power source would make it work.

If you need i can try and make copies of the FSM and post them.

PS. my buddy did the same swap in a 72 satellite last year. Without a doubt a very cool and worthy upgrade! He loves it!

I think that gives me what I need. I just need to get a two wire socket that won't ground on the cluster. The ground does come from the ebrake switch. Thanks for the info.

I hope to post some pics of this little project soon. I have two aftermarket gauges (tach and temp) in the pods (installed from the inside to look factory) plus two more where the radio goes. All slick and painted, no wood grain. The lens are all sanded and polished to look like glass.

Honestly, you should have ( Like I did ) change the harness too... less time, better sure about and they are available all around in good prices.

some differences between standart and rally cluser/harness:

On standart, gauges just work getting power from one BLUE wire, what is RUN source from ign switch. Is the same wire what does feed the oil light and brake light positive sides.

On rally, the gauges are being feed by ACCESORIES from ign switch, so if you put in RUN and in ACC ign switch you will have reading on both.

Then also Rally harness feeds a ground to the cluster through a spade terminal to voltage limiter. Standart gauge gets the ground on circuit board thorugh the hex screws directly from chassis

I'm all ready deep into altering my harness so I'm going to finish with it. It's really not that bad to do. I see the difference in the power source and grounding in the wiring diagrams. The grounding is no big deal. As far as the power hook up goes I plan to bring the blue wire in to the brake light socket and splice to the 12V side of the voltage limiter. The factory wiring shows power to the voltage limiter coming from a purple wire that also goes to the wiper switch that gets its power from the same type of source as the blue one so either one should work.

The only factory gauges I'm using are the speedometer and gas gauge so the gas gauge is the only reason I need to use the voltage limiter. Everything else will be aftermarket and easy to wire.

Thanks for the imput!

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I hope to post some pics of this little project soon. All slick and painted, no wood grain.

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Well I can't wait to see them... Plz post some soon!

I have two of these cars, a 71 road runner that will go pretty much stock and the car pictured in my sig that I am doing all the modern upgrades to.

I never really cared for the wood grain look in these particular cars and the radio is an abomination, what were they thinking???

I have a few damaged outer bezels for these style instrument clusters that would make perfect test subjects for modification.

I haven't done anything with them yet cuz I haven't made up my mind as to what I'd like to do to them.

So I'd definitely like to see your work.