Wiring advice needed: changing from 73 to 71 front end

7173Mustangs.com

Help Support 7173Mustangs.com:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

ScooterDog

Well-known member
Joined
Aug 7, 2015
Messages
89
Reaction score
0
Location
SE Wisconsin
My Car
1973 Mach 1 Q-code
Can someone confirm some wiring info for me? My 73 has a 71 front end, so there is no wiring for the fog lights. I bought a complete headlight wiring harness from a 71. I'm assuming it will be plug-n-play. Is that correct?? Or will I need to replace the harness under the dash as well?

 
Midlife is your best source for that info. I do know that the harness is very specific to year and model. It took me almost a year to find a complete harness for my 73 vert with air, tach, gauges and convenience group.

Beware of what is on eBay they say 71 - 73 but Midlife will tell you they are not all the same.

It cost me $300 for everything with no cut wires which is almost impossible to find. That is lights, engine, under dash every wire. None of the wiring from the kick panels back was included. I did get the in door speaker wires with good boots also.

I am guessing you will just need the harness coming from fuse box to the engine and lights. But I am not expert for sure. PM Midlife if no answer.

David

 
There are a lot of differences between 71 and 73 harnesses

You might be better off just making some adapter harnesses for the

parking lights and sports lamps.

 
Every year 71-3 headlight harness is different. However, their basic functionality is there and usable, so long as you're not interested in the carb solenoid, seat belt warning system, and "sportslamps". The 71 has a unique connector for the voltage regulator (green/red wire) that won't mate with the 72/73 versions.

You say your car has a 71 front end. What do you mean by that? Is that a front clip (all sheetmetal forward of the windshield pillars)?

 
Probably just the grille and lower valance (with the signal lights) - I would think the actual 'front clip' should pretty much be the same with exception of the bumper mounts (I have a '72 front clip on my '71 for instance, but noted no real structural differences to speak of). I think the bumper brackets are actually bolt-on deals for the '73s anyway (I could be wrong, though). :cool:

 
Every year 71-3 headlight harness is different. However, their basic functionality is there and usable, so long as you're not interested in the carb solenoid, seat belt warning system, and "sportslamps". The 71 has a unique connector for the voltage regulator (green/red wire) that won't mate with the 72/73 versions.

You say your car has a 71 front end. What do you mean by that? Is that a front clip (all sheetmetal forward of the windshield pillars)?
Hi Midlife! Thanks for the reply! I mean it's a '73 with a '71 lower valance and grille (including sportslamps and turn signals) - maybe all the sheet metal as well?? This was done prior to me getting the car, so I have very little history. There is currently no wiring for the sportslamps. So... I bought a 71 front wiring harness that may have been to you, as it came with the print out of all the wire colors/connectors.

I have an aftermarket carb and no seat belts (yet), so no worries there. Isn't the connector for the voltage regulator on the alternator harness? Not sure about that.

Anyway, would I be smarter to splice the sport lamp wiring into my existing harness? Or should I go ahead and use the "new" harness?

 
Everything depends on what you want the sportslamps to do. If only to turn on when your headlamps are on, simply wire them to the orange/red wire going to the dimmer switch. These will be a two wire affair: orange/red for power, black wire for ground. If he bulb sockets are three wires, use the wires associated with the two main pins in the bottom; avoid the third line on the side (true ground). If you want it to act as the 73 with running lights and turn signals, it is a bit more complicated to wire up. This is a three wire affair: running lights, turn signal, and ground (side contact on the lamp socket).

The third choice is not to wire up the sportslamps and use them only for decoration purposes.

 
Back
Top