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MG MGA - Wiring the A

I am about to rewire my 60 A. Does anyone have any helpful hints as to how to do it. I have never done any wiring before. I have all tghe harness necessary to redo the entire car. Shall I drop the dash and wire the gauges before slipping it thru the firewall or what? Should I start at the rear and work forward or from the engine back? Any and all help is appreciated.
Thanks, Jack
Jack

One hint is to cut off the old harness instead of unplugging and unscrewing it. Leave a short piece of wire on each connection, so you can see the colors. When you put the new harness in, do one connection at a time removing the old short piece and attaching the new. Also make a copy of the wiring diagram, so you can check off the connections as you make them.

It has been a long time since I did mine, so I don't really remember. I had the dash out for painting, and believe I wired most of it before reinstalling the dash. I know I still ended up on my back under the dash connecting wires.
Jeff Schultz

Thanks Jeff,
One other question. I have some instructions for "Wiring the 1500". Is this the same for the 1600? It does say that the 1500 is different than the 1600 for the turn signals and fog lamps(mine doesn't have fog lamps). Other than the turn signals, is there any difference?
Thanks, Jack
Jack

I depends if you like it original or not. I rewired my MGA out of any advice. I used nisan micra fused box with 10 fuses and spaces for 4 relays. My reason was, if there is short, I like know where it is. With one fuse it is hard to find. My fuse box fits nicely behind heater box and is hard to see. It is hard to solder old coroded wire without melting 50% of isulation. Heat sink does not work too well ether.
If you are interested I will let you know the details of my instalation, wiring diagram, to do it, and some tricks to do harnes.
Martin
martin

I don't know of any differences other than the turn signal relay(only on the 1500) and the extra tail light on the 1600.

I don't think there is any difference in the fog lamp wiring between the 1500 and 1600. There will be a red/yellow wire in the harness that goes from the fog lamp switch up to the front. If you don't have fog lamps, you need to make sure the bullet connector at the front has a mating insulated connector on it or is otherwise insulated from ground. The lighting circuit is not fused and if the front bullet connector for the fog lamps touched the metal chassis, and the fog lamp switch were turned on, it would smoke something. Or else, just don't connect the red/yellow wire to the fog lamp switch.

ps here is a simplified color code for the wiring harness. http://www.mgcars.org.uk/mgcc/sf/980903.htm
Jeff Schultz

The best tip is to lay out the new loom on a big table / on the floor, and using a meter and a blown up wiring diagram, locate and label every individual wire before you offer up the loom to the car. It's much easier to do this on a table than in the car!

Wire up the sitches for the dash separately before fitting the switches to the dash. Mount the gauges in the dash, and get a helper to hold the dash as you mount it in the car (saves scratching the ends of the panel). Then mount the switches to the panel, and connect the gauges to drive cables etc. (I changed the metal panel on my car a few weeks ago, and did the whole job in an hour to give an idea how long this version of the process takes), including dropping the top end of the steering column to get space to work on the dash from above. Install the dual gauge last of all when all else is done on the dash.

work from one end of the car to the other during the install, it's easy to do this when each cable is correctly identified and labelled in advance, and saves a lot of getting up and down.

Fit some extra fuses in the lightiing circuit. In line fuses are fine and easy to include without a major hack of the loom.

If you make any mods to the loom, solder them or crimp the connectioins using a PROPER crimp tool (not the pathetic pressed metal ones) and use some heat shrink to support the joint. I always buy crimp-on connectors that have separate push-on insulation rather than the ones wher the insulator is fitted and damaged by the crimping process.

get a 2BA spanner for all the small bolt-on connections (fuel gauge, dynamo, fuel sender, coil)

dominic clancy

Jack - Dominic has the right idea, lay out the harness and use a meter to locate both ends of each wire and then mark the ends as to where they go. You can get wire markers that are numbered 1 to 99 that are easy to wrap on each end of a wire and then make up a table of where each end goes. This makes it much easier when you are standing on your head with arms and legs wrapped around the car at unnatural angles to determine where the wire ends belong. Take the drawing for your car to Kinkos and get an enlarged copy made and have it laminated (under $10). You can then use a grease pencil to mark the circuit you are working on as you go. The 2BA spanner is a real help, in fact I opted for the complete set of BA spanners years ago and have never been sorry. Have lots of shrink sleeving on hand and go to Lowes or Agent Orange and pick up a heat gun rather than using matches or a lighter, makes a much neater installation. Finally, when everything is done and you are ready to hook up the battery, do so through a 10 amp fuse. Better to go through a box full of fuses than watch your brand new, expensive harness and all the hours of work go up in smoke (besides, none of the wires will work once the smoke has been released). Good luck - Dave
David DuBois

As you begin to test the wiring DO NOT immediately connect the battery. Instead substitute a trickle charger with a circuit breaker. That way if you have a wiring error you won't burn up the harness. All that will happen is that the charger will trip its breaker. This will work for all circuits except for the starter, but that's dead simple anyway.

Cheers,
Lew Palmer
Lew Palmer

Hi Jack
the wiring loom should fall into place when installed, there arn't many wires on an A, the wiring diagram in the manual explains where they all go. I assume you have a new loom and all the colours are visible? Put the thick part through the firewall/bulkhead and start with the dash wire's, get comfortable with a torch and tools and spend a couple of our sorting it out, the rest is easey. Don't connect the battery until you've found a home for all the wires or insulated any unconnected ones
Terry Drinkwater

Jack,

One caveat- attache the "one of one" connections before the "one of many" wires. Example- after attaching all of the light wires, you realize that the turn signal wires won't reach the electropneumatic trafficator (turn signal switch). I bought a Toyota Supra that had its engine replaced and the knock sensor wire (sheilded coax) wouldn't reach unless you pulled the intake. Bough a "repair kit" for 40 bucks and spliced it in.

Good luck,
Bill
Bill Eastman

This thread was discussed between 03/07/2005 and 06/07/2005

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