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MG MGA - wiring harness threaded through MC box/bracket

I'm working on cleaning an painting the heater box shelf. I want to pull out the master cylinder mounting frame, which Moss diagram (118) calls the 'box'. The MC is out...that was the easy part. There is a fibercovered wiring loom fed through the holes in the 'box' (side-to-side)! I'm trying to post the picture.

Question...Where is the nearest point of disconnection of the wiring loom to pull back through the bracket? OR...should I just cut it, and solder on a 4 conductor weather tight connector?

The wiring to the wiper motor is all set. I disconnected it at the motor terminals. This main loom goes through a grommet on the wheel well down beneath the car.


rpb bunch

If I were you, I would disconnect everything to the right of the bracket in the picture and pull the wiring through, rather than cut and join. Think yourself lucky you have a left-hand drive car, it's a bit more involved with a right-hand drive!
Lindsay Sampford

I think that is the wiring to the headlight dip switch(high/low beam switch). I think the only place to disconnect it is at the switch.
Jeff Schultz

I had the same problem. I cut and soldered.It worked fine but I knew that I would be replacing the loom when I did a full resto.
Matthew
M S Randell

I would just unscrew the wires from the headlight dip switch and pull them up through the grommet.

They are supposed to go through a hole and grommet on the shelf right under the wiper motor. If it goes through the wheel well then it may be a mistake or kludge by some previous owner.
http://mgaguru.com/mgtech/electric/et100a.htm

PS make sure to put the wires back through before reinstalling the wiper motor as it is difficult to get them through with the wiper in place.

Jeff Schultz

I've got a couple of days of business travel ahead. I'll dive underneath and track the wires where they exit the engine compartment. Hopefully, it will be easy enough to disconnect from the dimmer switch. The wiring diagrams show three connections to the dimmer, and this section of loom is carrying four wires.

Stand by for more information.

Thanks,


Rick
rpb bunch

Rick,

I did the same project last year. I found it worth the time to disconnect the dip switch and wiper motor.

For peace of mind and safety sake, consider wrapping the bare parts of the wiring loom with non-stick vinyl tape. Particularly where the loom passes through the MC bracket and firewall. A new firewall grommet for the head light dip switch wiring would be a good idea as well.

My biggest problem is keeping each project to a managable size.... Seems like each time I get started with a seemingly small project, the rabbit hole gets deeper. :-)

I have attached my 2009 before image. The after picture will follow.

John





jjb Backman

Here is an after shot showing the vinyl wrapped loom before installing the wiper motor and MC. This year I did the other side and heater.

John


jjb Backman

I'm in the process of stripping down the car to a bare shell and I've still to resolve the dip switch wiring. This could be PITA to do , just above the dip switch the wiring harness goes through a P clip, effectively clamping the harness from just puling upwards. Access to the dip switch is difficult due to the position of the dip switch bracket, access to the P clip, mounted at the top of the bracket is non existent. You could unbolt/ unscrew the the dip switch bracket with two people or gorilla length arms to get access to the P clip. Short of this cut and rejoin given you're planning on a new harness in time. Good luck and long arms!
Tony
A.M. Leyva

John...this is exactly the approach I had in mind. Clear out the shelf on the driver's side,wire brush, prime and paint everything, and repair the wiring loom.

Hopefully, mine will look alot like your 'after' picture once I get another 'play day' to work on it. I'll post the 'after' once I get this far.

Is it the standard routing to have this part of the loom pass through the large holes in the MC box? Can't believe this is 'factory'. Where is the correct path?

Agree...each 'little' project is like a piece of loose thread on that prized sweater...pull on one, and much more unravels than was originally bargained for. ...and that's part of the world of owning our 50 YO LBCs. And why it's especially good to have a forum like this to find out how others kept a manageable boundary around their own weekend projects!
rpb bunch

Rick,

When I took my MC out the loom ran through the large holes so that is where I routed things on assembly. On page 79 of Clausager's, lower right picture, seems to show the loom running under the MC on a Deluxe.

Here is my after pic of the other side. The bottom of my heater was pretty crusty so it was totally stripped and rebuilt. The original heater core is still good. The heater motor just needed new brushes.

Next up, replacing a leaky water pump.

John


jjb Backman

I tracked the wiring loom to the dipper switch, just as Jeff recommended earlier. One thing that was puzzling me before I pulled it apart was that there was a bundle of 4 wires running through the shelf into the cockpit. Catalog views of the dip switch show only 3 terminals. Mystery wire? Nope...once I got things cleaned up, I could see that 2 wires blue/white stripe connected in common to one switch terminal.

Dip switch is removed, cleaned up, and awaiting replacement.

Wiper motor...same thing.

Wiring loom re-wrapped.

MC brackets wire brushed and painted.

I'm going to clean up the heater shelf today, do some painting, and hopefully by the end of the day tomorrow, everything will be back in order so that we can take a holiday cruise on Monday!

rpb bunch

RGB, on the dipper switch, one blue/white wire goes to the headlamp main beam, the other goes to the main beam warning light.
Lindsay Sampford

This thread was discussed between 28/08/2010 and 04/09/2010

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