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MG Midget and Sprite General - 78 Midget & Ignition TROUBLE

Normally turning the key switches on power to the fuel pump and coil etc. Now it does nothing.
Turning it to start should connect the brown to the white / red stripe wire for starter - but nothing with either switch.
If I use a jumper wire at the back of the switch instead I get starter power.

To get it home I jumpered between my brown at the fuse box to the switched power connectors and then touched brown to white/R at the back of the ignition switch to start. In other words I hot wired it.


Help me with some steps to diagnose this please, here are the wires at my key switch:

Brown (+12v)
White / red stripe (to starter)
White / green stripe (??)
White (??)
Gray (??)

I also have a spare electrical part of the switch.

I just took apart one of the switches.
Two ball bearings, two copper contacts and some springs were in there.

The springs are in small holes in the plastic.
One sticks out about 1/8 inch while the opposite spring was pushed down in the hole and not sticking out.

There is a bit of melted looking plastic in there as well.
Rick Bastedo

Brown (+12v)
White / red stripe (to starter)
White / green stripe (??) IGN controlled accessories - works with key at "ACC" and IGN ON.
White (??) IGN Everything that only works with key at "IGN"
Gray (??)Think that is the annoying buzzer

"I just took apart one of the switches.
Two ball bearings, two copper contacts and some springs were in there.

The springs are in small holes in the plastic.
One sticks out about 1/8 inch while the opposite spring was pushed down in the hole and not sticking out."

That and next below would be your problem

"There is a bit of melted looking plastic in there as well."

Caused by bad switch connections getting it hot, or overload from something doing same.
Look for contacts that have sunken into the base as well, caused by and causes of same problem. That also gives loose rivets holding the contacts, which also creates heat, etc. Also damaged wire connectors at the switch, if they are plugin types.

A good example of why relays on the WG and W circuits are your friend!

FRM
FR Millmore

I just got back from NAPA auto parts.

I bought a new fuse block that uses modern fuses, 15 feet of 12 GA brown wire, 20 new female blade type connectors and a stock of fuses.

Also a new key switch to mount to the console, like my Mark II Sprite has on the dash.

This stuff is going to start working right and being dependable. Right now!
Rick Bastedo

So I got a generic ignition switch from NAPA.
Looks a lot like the switch on the dash of my Sprite.
Installed it in the steering cowl, works great.
Also put in a fuse block that takes the mini fuses.
Then fed it with battery from a relay so that when the key is on that block gets voltage.

Then I separated out a bunch of my wires and put proper ends on and plugged it all in.

Now almost all the electrical in my car works.
Still no gauge lights, but that's the only thing that isn't working now.

I'm way happier with the electrical system now.

I also swapped in my spare Midget fuse block for the old one and couldn't get voltage to go through it. Went across the street to True Value and bought a .270 rifle bore brush, chucked it up in my drill and went to work on the contacts.

Now it's working great!
Rick Bastedo

Go back to True Value and get OxGard or similar.
In the AC electrical area, sold to use on cables in breaker boxes etc., especially dissimilar metal connections. Put that on all your electrical connections, especially Lucas fuse boxes, end of problems.

FRM
FR Millmore

Is that a dielectric grease?

I need to tie down the wiring a bit but here's what it looks lke now.
The reddish pad under the new fuse block is 1/8" rubber.
The brown side is battery positive that is fused before it feeds this box. The output side feeds things like my electric fan, heater fan, cigar lighter.

The 40amp relay trips when the key is turned on, providing battery + to the new fuse block. Now very little current passes through the ignition switch.



Rick Bastedo

Rick -
OxGard is a grease made to dissolve and prevent the formation of oxides, especially in dis-similar metal electrical connections, like entrance panels that have Alu/Cu contact points. Dielectric grease is insulating to prevent current drain, and prevent moisture and oxygen from getting into a connection, so it helps on new stuff but doesn't clear up dirty joints.I use OxGard on all electrical contacts.

Not to be picky, but I'm glad your car is a whole continent away from me! I try to make some effort to maintain colour coding, or at least make it non-ambiguous. I hate crimp connectors, and solder everything. The white plastic four brown connector has proven to be a major source of voltage drop and frequent problems on MGB - does it get warm when everything is ON? I have measured drops in excess of 2V across thart connector with everything ON and the car running at 2500rpm. Ox Gard can help a lot on that, though it is best eliminated.

Be aware that under some wiring configurations, IGN relays can become "locked on" due to feedback through the Alt warning lamp. To make it more confusing, it can vary over time as the result of voltage balances changing or sensitivity of the particular relay you have. Further, later cars (MGB) can also have such a feedback through the brake/handbrake warning light system, which has diodes and other devious devices installed. This "might" apply to your late Midget, you'll know if it won't turn off when you turn the key OFF. This is a known problem with '77 MGB US cars, due to a factory error. Details on Paul Hunt's site.

FRM
FR Millmore

Thanks FR -

Your wiring description was helpful.

I'm not sure what you are pointing at with "The white plastic four brown connector" - please elaborate.
You mean the loops with the yellow crimped female blade connectors?

No the wires don't get hot.
Yes I did actually keep with colors (close as possible) when I was connecting to standard wiring.
The green wires go to green wires that were too short to reach. Other wires go to things the car didn't have originally like the electric radiator fan.
The big yellow wires go to the Halogen headlights, they connect to the lights via bullet connectors so that is easily reversible should the need arise.
I also keep a list of what colored wires do what in the glove box.

One further note, the wires to the ignition were getting very warm before the breakdown. The inside of the ignition switch partially melted and this is why the thing stopped working.

I no longer route much current through the ignition switch.

As far as being glad to be on the other side of the continent, well just so you know I don't feel that way.
If you are afraid my wiring job could somehow infect you or my car burning up in a giant Midget fireball could somehow harm you then I apologize.
I like soldered connections as much as the next guy, but I don't have the luxury of taking my car off the road for long and needed to get this job taken care of so I could continue to drive.

My current situation is that I have no shelter available for working on my car, so I must either work in the rain / snow / wind etc.. or wait for that few minutes we get in the month of March to make needed repairs.

This is the way things are, I accept it.
I'll do the best I can with what I have.
Rick Bastedo

Rick-
"I'm not sure what you are pointing at with "The white plastic four brown connector" - please elaborate."

>Just left of your new fusebox in the pic. I haven't been afflicted with a late Midget since I became aware of this problem. On late MGB, there are two fat N wires from the solenoid that feed all power to the car; evidently they needed to increase power capacity but didn't want to use a bigger, stiffer wire, so they doubled it. Then all power from the common connection inside that plastic is taken by two more fat N, out to the car. The connector has enough resistance, especially if overloaded, as yours may well have been, that it gets hot enough to oxidise the contacts and reduce the spring tension on the female connectors, which makes it worse.
My solution is to use a common feed 6 or 8 fuse block, available at most autoparts stores. Both N from solenoid are joined at the common feed point with ring terminals. Then I scramble the existing power feeds and any added ones, and run them off the new fuseblock. Saves all those looped feeds you have! All power to the car including those to the OE fuse box then are fuse protected at the new block. I'll attempt to attach a pic of a B rework. DCP-0588

"Other wires go to things the car didn't have originally like the electric radiator fan.
The big yellow wires go to the Halogen headlights, they connect to the lights via bullet connectors"
>Fan and headlamps should be fed by relays powered off the new fusebox.

"I also keep a list of what colored wires do what in the glove box"
>I draw a diagram, laminate it in plastic, and include in the car. Also local diagrams and labels for fusebox sealed in waterproof tape right on or near the components.

"If you are afraid my wiring job could somehow infect you or my car burning up in a giant Midget fireball could somehow harm you then I apologize.
I like soldered connections as much as the next guy, but I don't have the luxury of taking my car off the road for long and needed to get this job taken care of so I could continue to drive. "
>Yah, Just so you don't call me at 3AM in a blizzard! But I'll come. Trouble is, temp repairs have a habit of begetting the need for more temp repairs, usually even more inconvenient than fixing it in your driveway under "emergency" conditions!

If you send me an email to address above, I can send some docs and more pictures to confuse you further!

FRM

FR Millmore

Oh I see, never knew that about the white connector thing.

Good to know!

Yes the yellow wires go to the Halogens and are fused with in line blade fuses on each side and each side has a relay of it's own.

Yes the radiator fan has it's own relay are is fed by the new fuse box and even has another fuse at the fan end of the wire.

I believe in all I've added 10 new fuses to the circuits and there are 6 relays. Each headlight has a relay, the heater fan has a relay, the radiator fan has a relay and the new fuse box is fed by a relay, additionally the brake switch feeds a relay.

I also have 5 spare relays and wired plugs just in case any of these fail due to corrosion or whatever.

I like your picture in that the mounting on the inner fender looks like a better idea - I'll be stealing that one.
Rick Bastedo

I got the 6 fuse block with the common power lug and installed it. Now I need to start connecting more of my circuits (halogens & radiator fan for starters) to it and clean things up.

Over the past few days I've been having what seems to be an ignition problem. Especially when cold I'll take off and it will randomly cut out. I need to put in new plugs cap and rotor anyway, it's something I do in the spring.
That could take care of it or it might help me find the real problem.

I'll take those two N wires in the white plastic connector to the power lug of the fuse block, that will reduce the possible points of failure.
Rick Bastedo

Yesterday I replaced the spark plug wires and the problem with missing / cutting out completely vanished.
Sometimes if you just keep replacing stuff you eventually get to the right things.
I actually really needed new plugs cap & rotor so I'm happy I did those too.
Rick Bastedo

Rick great you're sorted - not trying to rain on your parade but also be aware new bits can be faulty too not that I'm suggesting yours are, previously lots of trouble with new rotors

my standard advice follows, you may already know some or all of it but it still stands, I hope you don't think I'm being patronizing as I'm not

buy a owners Handbook as it tells you so much you need to know as to own, drive, service and maintain your car - http://www.amazon.co.uk/MG-Owners-Handbook-Midget-Akm3436/dp/1855201763/ref=sr_1_2?ie=UTF8&qid=1301414187&sr=1-2

always have the battery in good condition and all battery connections and leads clean, secure and protected, same for all electrical wiring and connections

As soon as possible from buying the car do a full and proper 36,000 miles service only miss out items that you have 100% proof have already been done very recently, including;
g/box and back axle oils
brake and clutch fluids
coolant
dissy cap, rotor arm and leads (buy good quality ones)
http://www.distributordoctor.com/rotor_arms.html
fan belt

Check the age of your tyres if they are 6 years old or more replace ASAP regardless of tread depth, this will improve, the braking, steering, ride, handling and possibly noise, of the car greatly

Use the car regularly - to get used to it, sort out any wrinkles and prevent others, and enjoy it

Every few weeks check your horn and wipers work (no problem if you use the car regularly)

Follow regular checks, servicing and maintenance as per owners Handbook

Drive in all weathers, the Midget hood should be very watertight if fitted correctly and the heater is more than adequate, if working correctly, for the small cabin

Do not do any cosmetic or improvement work for at least 12 months of regular use, unless you need to replace parts or components, as you may need to use the money elsewhere on the car

Also very useful, you can get suppliers catalogues for free to get you started to see where things go but in my personal opinion they’re not as good paper copy like - http://www.mgocshop.co.uk/catalog/Online_Catalogue_Parts_Lists_3.html
Nigel Atkins

This thread was discussed between 11/03/2011 and 29/03/2011

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