[Mgs] New Harness has arrived

[Paul Hunt]

That's going to be a lot of labelling.  Most things fall out close by the 
component they attach to.  Probably more important is knowing which colour 
wire goes on which spade etc. of the component you are by.  As such it is 
probably more useful to cut the wires off the components leaving a couple of 
inches of coloured wire on each.

Depends on year, but some later harnesses have several in-line fuses.  The 
one I received had green connected to green and white/brown connected to 
white.  Sounds logical, but it had me scratching my head a bit, as 
white/brown should go to green in each case.

Pulling the old harness out rather than cutting it off at the firewall is 
good practice for getting the new one in.  Tape the various spurs of the 
main run in the engine compartment some forwards and some backwards, so as 
to end up with as even a thickness as possible.  Pull out back into the 
passenger compartment, and pull the new one in from the passenger 
compartment.  There is a double-skin at the firewall, put split tubing round 
the edges of both before pulling the new one in.

I fuse is a good idea before finally connecting the battery, in the ground 
cable as that should be the last thing you reconnect on completion of the 
job (and the first thing you disconnect before removal).  You may need more 
than 5 amps to test some circuits, one of the standard 17/25 amp will be 
fine for everything except cranking of course.  If the fuse *does* blow then 
connect a high-wattage 12v bulb in its place, like an old headlamp bulb. 
That will glow brightly while the short is on, and dimly or not at all when 
it isn't, which is a very useful diagnostic.  However whilst it will allow 
low-current circuits to work near normally, higher current ones won't work 
as brightly or as fast.

Use new bullet connectors at the front of the car at the very least, if not 
everywhere.  On the old harness I removed I found corrosion had run down the 
copper conductors of the headlight wires at the front of the car for a 
couple of feet.  The bullets on these are only crimped, and not spot-welded 
like spades, so I drilled a dimple in the end of each bullet to show shiny 
brass (bullet) and copper (conductors) and filled the dimple with solder. 
If you use a high-power iron briefly you won't damage the insulation. 
Polish the spades on components in the engine compartment, at least.

PaulH.

----- Original Message ----- 
> My new main harness has arrived from British Wiring. This will be my
> first experience changing out a harness...