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MG MGA - Wire Harness Change

Upon all of your advice, I'm going to attemp a full change of my Harness (1500), Gulp. I'm sure I will have many questions...and here is the first. I have the harness laid out and am tagging all wires following the process in A-Antics. (everyone says thats the best and easiest to follow). It was mostly straight forward. BUT... the section thats goes from engine thru firewall to behind dash has a split that has Eight wires. (Page 151 Section E)The book tells you exactly what is there and then goes on to tell you what each of these wires goes to but only mentions Seven. It says there are 8 (there are) but only tells you the route of 7. The one wire not IDed is Green w/Brown and has a bullet end. I think this goes to the Blower Pull Button (B) b/c the same color wire comes out of the harness (inside engine bay) to go to the Blower itself. Any thoughts?
I marked the Main, Rear, Taillights, and Frontlights. A-Antics seemed to say that the front light harness would be built into the Main. Were they sold like that once?? Only after I attached the Main to the Front did their discription make sence.
Have not maked the Under-Dash one yet, but A-Antics does not have the easy walk-through for this one that it had for the others. I know I can lower dash down and should be able to put the whole 'under-dash harness' on, but Antics does not give me the local of all these wires (and lights)??
I guess this is 3 questions and sorry for the long post. WTM
Bill Mitchell

Hi Bill. i consulted my 1500 wiring diagram. The green and brown wire does seem to be connected with the blower circuit. Is there a female receptacle on the blower switch that will accept the bullet connector? If so, that is likely where it goes. The front light harness feeds both front sets of lights, headliights, turn signals and parking lights. As for dash wiring, just follow the colour coding in the wiring diagram. Watch the wires going to the gas guage. You dont want to reverse them. There are several black ground wires with ring connectors. These ground wires connect to the instrument mounting bolts, and are held on by the instrument mounting nuts, which are usually knurled if memory serves. Hope this helps! Glenn
Glenn

Glenn
There are no female connectors on the harnesses, just the bullet ends. The female bits are double ended and you put a bullet in each end of the female bit to join two cables.

dominic

Dominic, you worldly traveller!!

I'm away from home, but I seem to recall that there is indeed a female receptacle on top of the blower switch assembly. It's actually just a piece of the metal assembly bent into a round shape that the bullet slides into.

Regards,

Joe
Joe Cook

The wiring harness has bulletted ends and most of the switches etc. have bulleted ends. There are double female connectors that are used to connect them. I highly recommend the connector tool sold by British Wiring. This tool will make the assembly alot easier.
Jim Pennoyer

Let me approach this explanation of the missing wire(s) from another direction, with recommended assembly sequence. The dash is a sub-assembly including all of the devices in the dash panel, and including the blower switch (if used).

There is a smaller stand-alone sub-harness for the dash. You can completely connect all wires of the dash sub-harness onto devices in the dash as an assembly, leaving only one thick Brown/Black wire dangling. That wire should have a BIG bullet connector. (The other end of that wire is connected to one side of the horn push switch with a small ring lug).

Now for the main harness, A-Antics is correct through six wires. The 8th wire Green/Brown (not mentioned) connects to the blower switch (when used). The 7th wire they did list, the thick Brown/Black, does NOT go (directly) to the horn button. This wire should have a BIG bullet connector and will be connected with a female sleeve to the similar thick Brown/Black wire (bullet connector) in the dash sub-harness noted above.

The idea here is to first mechanically assemble the operating devices into the dash panel. Then connect the dash sub-harness to the devices in the dash, leaving the one Brown/Black wire (with bullet) dangling. This much you can do on the workbench away from the car.

Then you can "offer up" the dash assembly to the main harness (sit yourself on the tunnel with the dash assembly face down on your knees), and proceed to connect all of the main harness wires to the dash devices. Finish by plugging together the two thick Brown/Black wires using a sleeve connector. This is the only interconnection directly between the two harness sections.

That sleeve connector is shown in this diagram: http://mgaguru.com/mgtech/electric/circ_fd.htm
Why that wire is not connected directly on the horn push is a bit of a mystery. Maybe it's just because the horn push uses small screw connectors which are difficult for access (above the heater control and dash braces) once the dash is in place.

After you have the dash wiring completed, you hoist the dash into place (offer it up to the body) and attach it with three screws at the top (with flat washers and lock washers) followed by the four small brace straps at the bottom.

How you handle the analog temperature probe through all this is up to you, just don't break it because it's a $100 repair. I'd say keep it tightly coiled and tie-wrapped until EVERYTHING else is finished. Then uncoil and run the probe through the bulkhead and connect to engine just before driving it out of the garage.

Barney Gaylord
1958 MGA with an attitude
http://MGAguru.com
Barney Gaylord

As a general note concerning the wiring harness- according to the MGA! magazines tech tips manual, the 1500 wiring diagram is not correct as concerns the wiring of the wiper motor. According to them, the 1600 diagram is correct. I haven't looked into this but wanted to mention it out anyway.

randy myers
59 mga
Randy Myers

This thread was discussed between 25/04/2005 and 28/04/2005

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