MGExp

MGA Forum

wiring harness

Moss Motors
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor

Topic List Forum List Newer Older Start New Topic
wiring harness
#1
gmkjr56 George Kress
Verona, PA, USA   USA
Sign in to contact
1956 MG MGA
1957 MG MGA "Coupe"
I am installing a new harness. Under the dash I have three brown with black wires. One of them has a but connector for the heater. The other two have no ends but I do not see where they go. I also have two white wires with no ends. Do they both go together?

Reply
Was this post helpful or interesting?
Yes No Thank
. Become a Supporting Member to hide this ad & support a small business
Re: wiring harness
#2
Jeffs72MGB Avatar
Jeffs72MGB Jeff Strong
Eden, NY, USA   USA
Sign in to contact
1959 MG MGA 1500
1972 MG MGB
Hi George,
Are you sure of the color of the wires? Is this for a 1500 or 1600? I have attached wiring diagrams of both 1500 and 1600. Hope this helps. Jeff


Attachments:
1500 Wiring.pdf    531.1 KB

1600 Wiring.pdf    320.3 KB
Sign In or Register to view this photo
Reply
Was this post helpful or interesting?
Yes No Thank
Re: wiring harness
#3
barneymg Avatar
barneymg Barney Gaylord
Somewhere in North America, Throw a dart., USA   USA
Sign in to contact
1958 MG MGA "MGA With An Attitude"
Two white wires under dash go to the ignition switch.
http://mgaguru.com/mgtech/electric/circ_a.htm

Two Brown/Black wires with bullet connectors are for the horn, and are joined with a snap connector. One of those is from the dash harness, and one from the main harness.
http://mgaguru.com/mgtech/electric/circ_fd.htm

Other Brown wires with a stripe (under dash) would be:
Brown/Blue = control box to ignition switch, and ignition switch to lighting switch.
http://mgaguru.com/mgtech/electric/circ_a.htm

Heater wires are NOT Brown/Black.
Power to the heater switch is Green.
From switch to heater is Green/Brown.
They both use snap connectors at the switch.
http://mgaguru.com/mgtech/electric/circ_f1.htm


Barney Gaylord - 1958 MGA with an attitude - http://MGAguru.com - barneymg@mgaguru.com - Ph: 630-946-3841
(Please email me direct, do not leave a PM on the public server).



Edited 2 time(s). Last edit at 2017-10-16 08:50 AM by barneymg.

Reply
Was this post helpful or interesting?
Yes No Thank
. Become a Supporting Member to hide this ad & support a small business
Re: wiring harness
#4
RJBrown Avatar
RJBrown Randy Brown
Queen Creek, AZ, USA   USA
Sign in to contact
1957 MG MGA 1500
1958 MG MGA 1500 Coupe
1960 MG MGA 1600 "Later"
1962 MG MGA MkII
White wires are the switched side of the ignition switch. They both go together to the same side of ignition switch.
The brown\black wires are the ground circuit for the horn(s)
In my car one of the 3 goes to the front of the car. This wire had a bullet connector and went to the horn button. The other 2 wires are two ends of the same piece of wire. One end goes to the other side of the horn button and the other end goes to ground. I grounded mine to the common ground point on the back of the fuel gauge.

Reply
Was this post helpful or interesting?
Yes No Thank
Re: wiring harness
#5
barneymg Avatar
barneymg Barney Gaylord
Somewhere in North America, Throw a dart., USA   USA
Sign in to contact
1958 MG MGA "MGA With An Attitude"
All ground wires should be Black. If there is a double ended Brown/Black wire under the dash, it is an error in the wiring harness.


Barney Gaylord - 1958 MGA with an attitude - http://MGAguru.com - barneymg@mgaguru.com - Ph: 630-946-3841
(Please email me direct, do not leave a PM on the public server).

Reply
Was this post helpful or interesting?
Yes No Thank
Re: wiring harness
#6
RJBrown Avatar
RJBrown Randy Brown
Queen Creek, AZ, USA   USA
Sign in to contact
1957 MG MGA 1500
1958 MG MGA 1500 Coupe
1960 MG MGA 1600 "Later"
1962 MG MGA MkII
Barney is correct, Originally the ground wire from the horn button to the common ground was black. I believe that the harness I got from Moss had a brown/Black one in the harness for this purpose.
Just crawled under the dash to double check. One brown/black wire came with a connector. It is the one that goes to the horns. The two that had no connectors come out of the harness about 1 inch apart. I put a grounding loop crimp connector on one and a bullet connector on the other. Wrong color originally but easy to identify as horn wires.

Reply
Was this post helpful or interesting?
Yes No Thank
Re: wiring harness
#7
gmkjr56 George Kress
Verona, PA, USA   USA
Sign in to contact
1956 MG MGA
1957 MG MGA "Coupe"
On the wireing diagram I have it looks like they go to a ground point. Both wires are brown with black.

Reply
Was this post helpful or interesting?
Yes No Thank
Re: wiring harness
#8
barneymg Avatar
barneymg Barney Gaylord
Somewhere in North America, Throw a dart., USA   USA
Sign in to contact
1958 MG MGA "MGA With An Attitude"
Someone should notify the maker of that wiring diagram that there is an error there. If the harness has a Black with stripe or color with black stripe were it should be a direct ground connection, the harness manufacturer should be notified of the error.

Only black wires should go to ground. Wires that are switched to ground will be black with a color stripe, or color with a black stripe. Conversely, any wire that is partly black is switched to ground, not a direct ground connection.


Barney Gaylord - 1958 MGA with an attitude - http://MGAguru.com - barneymg@mgaguru.com - Ph: 630-946-3841
(Please email me direct, do not leave a PM on the public server).



Edited 1 time(s). Last edit at 2017-10-16 03:19 PM by barneymg.

Reply
Was this post helpful or interesting?
Yes No Thank
  DougTD thanked barneymg for this post
Re: wiring harness
#9
gmkjr56 George Kress
Verona, PA, USA   USA
Sign in to contact
1956 MG MGA
1957 MG MGA "Coupe"
Randy, My harness is exactly like yours. I am going to do the same thing you did. Thanks for the help.

Reply
Was this post helpful or interesting?
Yes No Thank
Topic List Forum List Newer Older Start New Topic

To reply or ask your own question:

or

Registration is FREE and takes less than a minute

Forums  

Having trouble posting or changing forum settings?
Read the Forum Help (FAQ) or contact the webmaster





Join The Club
Sign in to ask questions, share photos, and access all website features
Forum List
MGB & GT MG Midget Buy, Sell & Trade Vendor Market MG Performance MG Engine Swaps Factory Correct MGA MGC MG Magnette 1100 & 1300 T-Series & Prewar EV Conversion Modern MG MG Motorsports Events & Meetup MG 2024 Katy Texas Other Vehicles Off Topic Clubs Archived
Your Cars
1962 MG MGA MkII Coupe
Gary Stella   USA
1962 MGA MkII Coupe
Text Size
Larger Smaller
Reset Save