Making LUCAS electrical systems WORK! - MGB wiring repairs PART 1

[@nigelbarton8350]

You’re spot on about being methodical, slow and steady wins every time on electrics. I’m nearly done on a bare shell rebuild on my 72 GT so had the whole loom on the bench, many many bodges. I bought a cheap used loom from eBay so I had a good supply of every colour wire, and added a kit car fuse box with 8 fuses and 6 relays so all the main circuits are split out now. And the main feed to this box is also covered by a 40a maxi fuse. So much easier to do with it all spread across the bench!

[@wallisparnell4464]

When i first got my car. I went section by section on the electrical system, and pulled apart, polish up male and female connectors, then coated the connector’s with bioelectical grease to seal the connecting. Found a few loose connection, adjusted to be firm connections, and a few corrosion connections. Believe system will long-term😂 be less troublesome.

[@briandawkins984]

I used dielectric grease on my 1980 B saved a lot of problems. I did find a red wire in the dash board - always live - that appears in no Canadian B wiring diagram. I insulated carefully and left it. Do not hack the loom ever!

[@c.brionkidder9232]

Good stuff! The difference in the alternator warning light is remarkable. Very methodical approach, I like it.

[@vwcoco]

Nice video Ross think I said before every Vw beetle I’ve bought and sold on ,the wiring always gets redone from scratch . Fault finding is good. Overdrive fix awesome m8

[@scottishcarenthusiastsandtrain]

Great tinkering video Ross, have to say that Unipart Radio looks really smart and I too was impressed with the internals of it. Shame about the Jack incident but I know you will get it sorted and continue to banish the prince of Darkness.

[@alanvinegar5729]

The run on problem is a defect in the factory wiring where there is some residual current coming from the coil preventing the solinoid from opening. They fixed this in 78. I can email you an easy fix that Glen Lenhard wrote in the mgexperience and John Twist showed me.

[@Endfloat]

Thanks. I actually got it fixed. 😎

[@range_rover-landp38]

Very helpful video, thankyou. I have a '79 GT that needs plenty of electrical work so I know I will be referring back to this video and many of your others too. Thanks again.

[@anthonygowland8363]

I also enjoy working on the electrics of my mg.... although it's all so flimsy there's never a lot of hope that the fix will last!

[@americanpatriot2422]

Lucas electrical issues and tinkering are the fun part of owning an English/MGB.

[@gregnovak0070]

Clearly you know what you are doing, but just thought I would mention a few things. I did exactly the same thing with the jack and also destroyed a rad. Now you have the wiring back to as it should be, sandblasting or replacing the fuse holder is a very good idea. Most of the issues are then generally earths, mainly the body to engine strap, think it connects to the gearbox cross member from memory and off course the box always leaks oil. I used to get a serious shock every time I used overdrive driving with bare feet. In later cars a relay was added from factory positioned next to the heater box on the firewall, it's a good idea, that solenoid draws decent current. Lastly, di-electric grease is your friend, Lucas gets a bad wrap, but it's an old car, cleaned and protected with di-electric grease the electrics are pretty reliable. If that earth strap is bad the dizzy earths through the speedo cable, so you might have issues with the speedo not moving as smoothly as it might and need to lube it up or replace it. The headlights and overdrive also benefit from relays and fuses.

[@Endfloat]

You're a star. Thanks so much for that info. I'll take it on board and work through the points you made.

[@norton794]

Morning Ross noticed you're missing the clutch return spring, you have the one for the brake but not the clutch. Another enjoyable video, shame about the radiator, one step forward 3 back, oh the joys of classic cars.

[@Endfloat]

Oh thanks! I didn't notice that!

[@donthuis]

If the solenoid clicks at all, it will only do so once upon activation, guess how I know. The internal plunger will not fall down for awhile at deactivation, even when the car is moving. BTW John Twist strongly advises fusing the feed for the OD circuit, especially for cars with the switch at the gearsift handle, where wires can be chafed to shorting... Cleaning bullits with a metal brush is cheaper, but will give faster oxydisation than using new bullits. A yearly inspection on bullits looking too oxydised and replacing them with new is the best approach

[@Endfloat]

Thanks! Couple of things for the to do list there!

[@donthuis]

@@Endfloat You're welcome. I am not only from my own jobs on the B, but also thanks to postings on the MG Experience site, well aquainted with the alternative approaches when it comes to spannering & electrics. Although I mastered on the UNI in ICT, basic mechanical and electrical basiscs were never forgotten.

[@gfurstnsu]

Never work under the car with only the floor Jack in place. Too many people have died trusting a floor Jack. You must put jack stands under the car against the frame rails and lower the car so the Jack stands have all the weight!

[@Endfloat]

I did have axle stands under the car. I never go under without them.

[@carstenmoore5760]

Nice work Ross. Your approach is very logical. Shame about the mishap at the end, but on the positive side the radiator is probably original, so due for a change before the inevitable happens! I share your concerns about the ignition circuit being unfused. For what it's worth I connected an inline fuse on the spade connector at the supply side of the fuse box in mine. It look original as it sits next to the other three inline factory fuses. Also serves as a useful immobiliser as if the fuse is removed the fuel pump doesn't operate. 😉 Looking forward to Part 2.

[@Endfloat]

Yeah I think I'll put an in-line fuse there. What rating did you use? Oh, and the radiator I smashed was only newly fitted by the previous owner! 🙄

[@carstenmoore5760]

@@Endfloat Hi Ross I've used a 15 amp in mine. I know its over the top as the overdrive only draws a little over one amp, but I'm keen to avoid nuisance blowing if the fuel pump is working hard. At least if there was a direct short the fuse would definitely blow rather than melting the wiring harness! Shame about the radiator but could have been a lot worse if you had been underneath, although I doubt you would ever attempt that without a secondary support.

[@OscarOSullivan]

@@Endfloat Why not replace it with a modern German or Japanese system

[@Endfloat]

@@OscarOSullivan what? The fuse holder? I wanted to get everything that's original working as intended rather than modifying.

[@OscarOSullivan]

@@Endfloat Fair enough

[@dfboiler]

I swear I have to do this to my 77 roadster, there are so many wires that I can't figure out what they are doing. Unfortunately I have zero patience and am not methodical. So it won't be me doing it. so many things get added to these cars and then get taken away and owners seem to never remove the adhoc wiring they set up.

[@wallisparnell4464]

Did have an issue, was tuning, and the tach burned up and the white wire from tach to fusebox, cooked. And ideas anyone why that happened? Thanks

[@ryanlukeb]

very good video! i have a question about the overdrive. i currently have a MGB 77 and the overdrive isnt working. when i've looked under the car, the wire from the solenoid isnt there. does the wire from the solenoid attach onto the interlock switch or go somewhere else? Thanks

[@Endfloat]

Are you sure you're looking at the solenoid? If the wires missing, you'll need a replacement solenoid cause there's no connector. The wire just goes straight into the solenoid coil. The other end is connected to the interlock, yes. Then it goes up to the switch.

[@ryanlukeb]

@@Endfloat Thanks for the reply. The wire conected to the solenoid is there, but there isnt any obvious wire for the solenoid to connect to. at 28:58 you can see that the solenoid wire connected to another wire. its this wire which i cannot locate. does this go into a block or stright into the interlock switch? Thanks

[@nomaam9077]

LUCAS - The Prince of Darkness. 😄

[@Endfloat]

Loose Unsoldered Connectors And Splices

[@douglasgreen437]

Those extra wires must have been part of an imobilizer/alarm...

[@Endfloat]

I reckon so, yes.

[@scoobyben1979]

Hey Ross, How did you get to the interlock switch? I need to test mine but my hands are a little too big.

[@Endfloat]

Unfortunately there was no magic trick. Just a LOT of swearing! I think I used a channel locks but I can't remember now.

[@kengatzemeyer3031]

Sorry to see the radiator problem, glad no one was hurt. Your car has a blue label O/D. Is that for only 4th gear or does it also work in 3rd?

[@paul196797702183]

blue label o/d was 4th gear only; that is, if everything works as it should. lol

[@Endfloat]

I've had 2 mg's with this overdrive and in both cases it works on both 3rd and 4th. It may be different on American market cars.

[@nigelbarton8350]

Remember it’s not the overdrive that determines which gears it works in, it’s the inhibitor switch on the gearbox. If the switch and selector mechanism allow current to pass in 3rd and 4th , any overdrive fitted will work in those gears. And vice versa.

[@gfurstnsu]

It’s the same on US cars. I have a blue label overdrive from a 1976 B and it works on both 3rd and 4th gears. It is good that you mentioned about the backing up with the overdrive connected. Almost immediately the overdrive is destroyed!

[@TheCaffeineRacer]

Where did you find the useful coloured wiring diagram please might be useful :) my 1979s wiring is bodged to I have an extra light on the dash no idea what it’s for lol

[@Endfloat]

Mgexp.com. They've loads of useful info on their site.

[@TheCaffeineRacer]

@@Endfloat thank you sorry about radiator

[@peterwilliams3202]

Exchange the clock for a volt meter. A volt meter is much more helpful than the clock.

[@bshnabel]

Good trouble shooting video

[@Marc-dm1fh]

Accident while sitting on the jacks? Nasty.

[@Endfloat]

It was just the trolley Jack that slipped. I didn't have it on the axle stands at that stage.

[@philippreen2807]

Bodgers really annoy me, nothing wrong with adding additional circuits, but use the correct colours for the loom. Best doing nothing than leave a mess for you to sort out. And scotchlocks, don’t start me....

[@johnwren3976]

Lucas is not the Prince of Darkness. Only Prince of Intermittent and Inexplicable darkness. Always hook one of the jack's lifting saddle horns behind the front crossmember.

[@Endfloat]

You definitely get a few curve balls from the Lucas electrics! My wiper motor locked up and overloaded the circuit that the fuel pump was on, killing the engine! 🙄