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MG MGA - Electrical-racing to Reno's Hot August Nites

After the wife threatened to have it carted off for being in the garage for several years in an un-running state, I am now racing to get the MGA 1958 Convert up and running for Reno' s Hot August Nights.

MGA STATUS: engine running (barely, need to set rebuilt carbs) hydraulics holding their own, clutch good, suspension adequate, body needs TLC….
HOWEVER, LUCAS God of the Darkness has struck:

The PO had mangled the electical wiring instead of fixing/cleaning up the original harness: PO laid new switches and wires to run parking lights, driving lights and a fuel cutoff switch (looks like spaghetti under the dash).

PROBLEM. Although the electrics were all working when the A went into hibernation 5 years ago NOW, whenever I turn on the lights (or even active the brake lights by hitting the brakes) the electrical goes dead (lose the gauges, dash lights, turn signals) for about fifteen minutes (e.g. lose the ignition switch-based portion of electrical system) Nothing runs. Then fifteen minutes later, the system comes mysteriously decides to come back on line and I can start up the MG. Have been looking of hidden circuit breaker somewhere under the dash but have not found any. This scenario does not seem to blow any fuses either.

-Does a faulty voltage control or turn signal relay have anything like this capacity to temporarily shut down the electrical system?

-Should I just pull out all the “newer” spaghetti wiring and try to get this going by cleaning up original harness (e.g., clean up the connectors with new contact sleeves)? (the lacquer insulation on wiring appears to be OK, but the cloth harness is coming apart-I have some harness rebuild ability- haveing rebuilt and rewrapped MGB wire harness-fixing radio supply wire burn outs and the like)

-Should I just give in and get a new harness?

Any thoughts on the matter would be greatly be appreciated.

John Long
J Long

Pull out all of the alien spaghetti, then reconnect and trace/repair original wires systematically. A fist full of new female snap connectors and cleaning up grounding points can cure a multitude of sins.

Start with the stuff that makes the car run, white wires to the fuse block, ignition and fuel pump. This requires contact with the brown and brown/blue on the control box, after which getting the generator and control box working is just a few more wires.

Then do all the red wires for the parking lights, dash lamps, map light, fixing any of the black ground wires as necessary to make this stuff work. Then do the headlights, high/low and dash lamp. What's left is green wires from the switched fuse, wiper motor, brake lights and turn signals, fuel gauge and heater switch.

As long as there are no burned wires inside the harness wrap, most of the problems will be at the end connectors. especially in the snap connectors. The bit that throws most novices is the bundle of snap connectors by the starter switch and another bundle at the RF and RR corners.
Barney Gaylord

There is a dirty or loose connection somewhere in the system. Could be as simple as tightening the screws on the back of the ignition switch, the voltage regulator or on the fuse box. The common connections are: the brown wire from start switch to the volt regulator, The brown/blue from the v-reg to the ignition switch and the white wire from the ignition switch to where the 3 white wires join at the fuse box.
That said I would go further than Barney's suggestion and just buy a new harness. With a clean new un butchered harness all the " Master of Darkness" BS goes away.
R J Brown

Barney, RJ, thank you for suggestions. Your color wire suggestions help a lot on what I should focus first on.

Got further into it and it looks like the PO overlaid newer wiring over the harness and did not cut up the harness itself. A review of funds (limited) indicate will first go with trying to reinvgorate the old harness (cleaning with electrical cleaner, dremel with with wire brush wheel and new set of bullet points and connectors, rewrapping it, etc.) and check the tightness of the various connections. Will eventually replace harness.



J Long

Look forward to seeing your car and to hearing the conclusion to this story when we come to Reno/Tahoe for MG 2011.
Peter.
P. Tilbury

I'm a strong believer in dielectric grease. Use it in every bullet connector as you clean up the connectors and replace the new females.

Depending on the hatchet job on your old harness, a new harness may give you some piece of mind. Either way, the grease is a good way to keep your efforts from going south in a year or two.


Chuck
C Schaefer

This thread was discussed between 23/07/2008 and 25/07/2008

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