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MG MG Y Type - New Loom Wiring nightmare

I'm nearly there when it comes to completing installation of a new wiring loom; I've picked up a number of hints tips along the way from the Y-Register team members. But you know when you cant see the solution and you round and around again! We'll 1st one - can anyone just confirm which route, what colours and what connects and makes the Windscreen wiper motor work, cos its doing my head in. I bench tested it months ago and worked fine, but now its in I'm not sure how best to prove whether the problem is the wiring, the motor or the switch behind the dashboard (which didnt check). I'm not an expert in wiring, in-fact I'm not and expert in anything so seeing I've made it to here ! Any help gents. Not forgetting not all looms are the same and or correct, so your diagram layout may be more useful, we'll see. Chris NB: More to come

Chris Blood

Persumably Chris, you are talking the YA/B wipers not the YT wipers?

Easiest way is to hotwire it temprarily from the battery direct to the terminals on the wiper motor, and from the wiper motor to earth.

Who made your loom? If you bought an Autosparks loom, they use the standard YA or YB wiring colours, which is why we recommend them as a supplier on the Links page. If your maker has not used standard colour codes this will make the job extremely hard.

ALL YAs use the following:
Purple and Black goes FROM terminal A4 to the wiper motor.
Green and Purple goes FROM the wiper motor to the wiper switch.
Black goes from the wiper switch to ground.

Only difference between early (pre (Y 0584) and later ones is the position of the A4 terminal on the control box.

I would begin first at the ground wire. A dirty or bad ground connection will stop everything before it starts.

If this is good and clean, check it is connected to the wiper switch (in front of the driver).

If this is good, does the switch close properly when the wipers are turned on? If so, check that the Green and Purple wire is properly connected and current is present. The entire circuit is live and only isolated by the switch which is AFTER the motor!

Then using an Ohm meter, check that you have continuity from the Wiper motor end of the Green and Purple wire to the switch. While you are there, you might as well also check that the wire from the switch to ground is not broken either by checking its continuity too.

Then finally check the continuity of the Purple and Black wire.

If your control box is working, so should your fuel gauge, as this is also on terminal A4. Given your other post, it may be that your control box isnt working. Your Stop lights, and power to the central horn/trafficator switch also come from A4 so if they arent working, you may have a problem with your control box. If this is the case, personally I would not recommend a novice tackling this but take it to a competent auto electrician who can repair these things. It is easy to over adjust them and cause a fire if you do not know what you are doing.

Paul




Paul Barrow

But of course Chris, you have a YB, dont you?

Same principles apply as with YAs except that:
Green wire goes to Terminal A4 and the wiper motor
Black with Green from wiper motor to switch, and
Black from switch to ground.

On the Control Box, you dont have a Terminal A4 - it is located on one of the fuse box terminals. I presume the fuse is good?

Feed to the fuse box is via terminal A3 and a White wire (to petrol pump), the SW side of your coil, and the ignition switch.

Hope this helps you,

Paul

Paul Barrow

Chris

In my YA the purple and black (aka Green in the YB) goes to the terminal nearest the firewall, the other wire uses the terminal furthest from the firewall. This is assuming that the motor is mounted with the gears uppermost and the cable then runs out to the side of the bonnet (if it were closed) before arcing smoothly round. There should be a black ground wire (with an “eye” type terminal) which I secured to one of the bolts on the wiper gear housing to earth it.

Does that help?

Paul
Paul Barrow

Chris

Does the attached photo clarify what I have been saying? It is from my YA.

Paul

Paul R Barrow

This thread was discussed between 22/09/2007 and 29/09/2007

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