New wiring harness

[rossco]

New harness coming. Main, pigtails, OD. Engine, tranny, OD still in car. What's the best order to work this? Front to back? Back to front? Under dash first? Any help appreciated.

 

[Randy Forbes]

Push the engine compartment wires out from under the dash; separate the bundle (from your temporary taping to pass them through the grommet/hole) into the wiring on the LH/RH sides of the engine compartment__the wires should flop/land very close to their connection terminals.

The only really hard part will be to secure the rear harness alongside the bellhousing, as there's just too little room with the trans in place (removing the trans cover may help some, but I'd settle for ty-wrapping the new harness to an old harness clamp until the next clutch job...).

Go ahead and remove all the old terminations, as the colors are likely so faded/grease or paint covered as to be of no help anyway. And again, the new wiring will land so close to where it terminates, that there should be little confusion.

STUDY the wiring diagram! BTW, you're not color-blind are you...?

Don't get overwhelmed thinking about the entire job, just concentrate on one (1) piece of equipment or gauge at a time.

Neatness counts! Try to avoid wires twisting over each other, and dress them out so that they flow from the harness bundle to the devices. In aircraft wiring, it is an absolute no-no for one (1) wire to lay across another, because if one (1) overheats and melts the insulation, it will short to the wire it crosses. It IS possible to manipulate the wiring inside the taped bundle to have them exit in an orderly fashion. It's not uncommon to undo a wire that's already terminated in order to make an adjacent wire look neater.

That's a start, good luck! If/when you get frustrated, walk away! When you return, it will all look clearer, and you'll be that much further ahead.

Oh, and be glad you're wiring a Healey, and not a modern BMW with miles of tiny wires, buss-communications and fibre-optics!

 

[Randy Forbes]

Looks like I gave you bad advice; this picture shows that I passed the bundle INTO the underdash area FROM the engine compartment:

This is the bundle "temporarily taped" to keep the loose ends from hanging up:

More pictures here, though it's a BJ8, some of the same will apply to whatever model you're working on: https://www.spcarsplus.com/gallery3/index.php/reMKIII/electrical_work

 

[Bob_Spidell]

You didn't specifically ask, but I highly recommend the 'Snap Connector Tool:'

https://www.britishwiring.com/Tools-s/42.htm

Pricey, but all but guarantees a good connection (and saves your fingers). I think Moss might carry them now.

Also recommend putting a dab of silicone dielectric grease in the fittings before connecting the wires. This will exclude air and water and help prevent corrosion. I know 'dielectric'--i.e. an insulator--seems counter-intuitive, but there will be enough metal-to-metal contact to assure good conductivity.

 

[rossco]

Bob. Where does one purchase 'dielectric grease'? Is vaseline not sufficient?

 

[PAUL161]

Sorry to butt in but, I get mine from NAPPA. PJ

 

[rossco]

Paul. Jump in any time. I need all the help I can get. "We never close". About the crimping tool; I ordered that with the loom. R

 

[Bob_Spidell]

Bob. Where does one purchase 'dielectric grease'? Is vaseline not sufficient?

Vaseline is a petroleum product and may, in the long term, degrade rubber components. Not sure of its insulating properties.

Any auto parts store should carry DE grease. There are a number of brands and sizes (it ain't cheap). Example:

https://www.seton.com/loctite-dielectric-grease-ee100.html?keycode=WS0194&gclid=CLPb2pzmsrkCFRDZQgodoXIAfQ

 

[bob hughes]

On my BJ7, I removed my harness in the engine bay and cut it off at the bulk head.

I then sat down with my new harness and a meter and the good book ( workshop manual) and checked each wire out and labelled them, also checking the that the wire colours were correct. Look out for differences in the connections old/new, I did not spot that there were differences in the connections to the overdrive relay until I was connecting up. Then installed the engine bay electrics - reasonably easy actually ( especially with the engine out). Once they were done, I then moved to the dash side, taped the wires up and installed a pull wire through the bulkhead and eased the harness through. I removed the instruments, cutting the old wires and leaving a tail/tails on the instruments so I knew which wires went where and proceeded to wire the new harness in. I also made some adjustments to the connections as I am now using wedge bulbs in the speedo and tacho and an LED in the indicator bulb position.



Bob