Nigel the 1977 MGB Wiring harness

Installation of Complete Wiring harness replacement on a 1977 MGB roadster.
mossmotors.com...
#mgb #classiccars #automechanic #restomod #restomods #britishcars #convertable

[@markstern8699]

Excellent video and information. Thank you!

[@bobharter3492]

Thanks alex. That is what I was planning to do unless you came back with something different.

[@americanpatriot2422]

Outstanding video and presentation. I always unwrap the blue tape on the entire harness on a long table and re-wrap it with new blue electrical tape as I unwrap. I do this it at the same time so as to keep the the harness in it original shape/configuration. You never know when the Lucas Gremlin has did its evil deed. I agree, you should always keep your original harness. Many of the connectors are no longer available. (such as the radiator thermostat sensor, brake failure sending unit connector, windshield wiper motor, door buzzer connector just to name a few. Important FYI : If one of those diodes goes out the starter motor will engage when you apply the the parking brake. This can be real bad for your starter and starter ring gear on your fly wheel if the motor is running.

[@jerryp2433]

Does it make any sense to cut all of the connectors off and solder directly? I mean how often do you have to remove something?

[@americanpatriot2422]

@@jerryp2433 Better to be safe and have a spare connector that is no longer available to make repairs than to buy an entire harness and go through the entire removal and replacement procedure. As our MGBs get older the original equipment (even though it is old) is of way better quality/fit than these replacement parts that are made in China, India or who knows where.

[@bluzzjazz]

I have a 74 MGB and looking at all that wiring makes my head hurt!

[@scoobyben1979]

Thanks again Alex. Been looking at replacing the rear loom as the reverse lights aren't working. But I might just run new cable for those instead.

[@AlexPlatacis]

You might take a look at thus video too kzbin.info/www/bejne/fKrVo2B7g76lh7ssi=54qazhfhWxPp1sO3

[@CaptPanOfSteel]

Thank you for this video! I'm replacing the main wiring harness for my 1974 MGB and this has been a very helpful general guide!

[@AlexPlatacis]

be sure to subscribe. I plan on doing a follow up video when I finally get to installing the Dash. it will include all the details on what wires go to what switches etc..

[@riverbedoverland]

So glad I found your channel. Restoring 2 is gunna be fun! Haha

[@ic5838]

Terrific video. Answered a lot of my questions. Many thanks

[@AlexPlatacis]

Thanks. I plan on doing a follow up video for the dash wiring and instrumentation. be sure to subscribe so you get a notification on that one.

[@paulbiegun]

Thanks! Excellent video with good narration and tips. ' 73B

[@sascenturion]

Wow.... That's a lot of work and most of of it in awkward tight places! ...😳😕 Well done! Great video ,interesting stuff Thanks 👍😀

[@c.brionkidder9232]

I've been on the fence about dropping the $ for a whole new harness or not, and I think your video just scared me into doing it!

[@windmill1965]

7:25 these are indeed diodes, Lucas type 83225A. The numbers you mention (7633 and 7634) are the manufacturing week codes: 1976, week number 33 and 34.

[@bobharter3492]

I watched the video where you did that. So, I made sure I didn't do that. Lol.

[@AlexPlatacis]

Well, only other thing I can think of is the connections near the Sprinkler motor where the two major harnesses connect. Hard to diagnose over text

[@CrapToCream]

Hey Alex, I was going fine with the placement of the wiring loom through the dash until I realised yours was LHD.... Ha Ha!!

[@AlexPlatacis]

Whoops. LOL

[@bobharter3492]

Hello again Alex. I was wondering if you firgured out where the 2 green wires that are close to the diodes went to. I can't find any documentation on those 2 wires.

[@AlexPlatacis]

I could not find anything either. In my car, I just connected the two together. They were the same circuit, so they go to the same thing. Likely just a manufacturing shortcut

[@Caesartherottie]

I have a 78 MGB, there is a wiring harness that has two green wires coming from it. One wire goes to the temperature sensor. Where does the other one go? It was unplugged when I bought it. The wiring harness is located just behind the alternator, thanks

[@AlexPlatacis]

I did another video on the dash harness. Maybe that will help out kzbin.info/www/bejne/r3jEmpWlqspggMU

[@AlexPlatacis]

To add to the solution, solid green wires make up a lower voltage circuit that is reduced to something like 10 volts. It is used for gauges like the temp gauge, fuel gauge etc.

[@donjames5761]

whats the green/white or green/red wire that goes to the back on the passengers side it passes through the glove box ?

[@AlexPlatacis]

The wires for the flashers, or diodes run behind the glove box. Hopefully, this video answers your question kzbin.info/www/bejne/l3TEgZ56lq2XmtUsi=JxJNePRWN8OTyl78

[@bobharter3492]

Hey again alex. I have the same wiring harness you have. Im trying to figure out the coil and distributor wiring. I have a ballasted system. I see that you have the segment with the 3 prong plug isolated. What i have left are 2 white/green wires together, 2 white/green wires together, 1 whte/blue wire and 1 white wire. Am i right thinking the w/g wires go to coil +, w/b wires go to coil -, w/b wire and w wire go to ballast resistor. And the long green wire goes to the distributor. Im so long winded. Sorry.

[@AlexPlatacis]

Yeah the resistor complicates the look but not necessarily the function. I have a flame thrower electronic distributor, and the coil has resistance. So my install is a bit more simplified. The thing about ballast systems is they bypass the resistor during startup to make a more powerful spark. Then once you release the key, the resistor kicks in to prevent over heating the coil.

[@AlexPlatacis]

I will lookup the diagram for you so you can set it up right. I did a video on a 67 mustang that shows that. But that won't help here (except for concept)

[@AlexPlatacis]

images.app.goo.gl/jvJ6PXz8njUkTzYj7

[@bobharter3492]

Hello again Alex. I basically have everything on the dash and engine wired up. However, I don't get any power to the ignition switch. I have 12.5v at the fuse box and to the in on the ignition relay. When I turn the key on, nothing happens. i assume that I should get 12.5v at the brown wire on the ignition switch. I have a good ground. Did you have any problems like this? Do you have any idea where I may look now? As of now, I am totally lost.

[@bobharter3492]

I forgot to tell you that I installed a brand new relay. Both the ignition and starter relays are brand new.

[@AlexPlatacis]

there is a relay on the engine bay just above the Coil. make sure the leads are connected correctly. I will try to find an image for you to see what it should look like. that is likely the issue.

[@AlexPlatacis]

Actually this video that we are making comments on has a good shot of both the relays you need to check. (right in the opening screen 1 second in)

[@AlexPlatacis]

so, I just had an idea... under the dash near the steering column, there are two sets of connectors that are the same shape. these are for the horn, ignition, and turn signals etc... funny thing is they fit in the wrong connector. you might want to confirm the colors match up on both ends of those connectors

[@bobharter3492]

Hey alex. Do you have a video or image detailing the connections of the alternator and the coil. I cant fid wherè the small loo. With the three wire plug that is near the alternator wired.

[@AlexPlatacis]

I am doing a year in review and viewer Q&A I will include your question in the electrical components segment. Send me pics of your B, I will add it in the video

[@bobharter3492]

@@AlexPlatacis ok. How do I send them.

[@bobharter3492]

Merry Christmas.

[@AlexPlatacis]

@@bobharter3492 [e-mail]

[@bananamuncher85]

do you have a video installing the wiring loom?

[@AlexPlatacis]

I have a few. Let me look to see if I can make a playlist

[@AlexPlatacis]

Yeah, I thought I had a play list setup... kzbin.info/aero/PL2RsH7Pa3wcFWHI1qiSJ1fvhGUY8pWCrr

[@ronwatson7888]

Can you explain to me the blue tooth / sound system for me please.

[@AlexPlatacis]

ha ha.. funny. 😄 but Actually... I have a video on that exact thing. kzbin.info/www/bejne/l5ariouhaaeYgZI

[@AlexPlatacis]

This video shows how to add a USB charging shelf in place of the Radio. so you can use your phone as a sound source for blue tooth wireless speakers

[@ronwatson7888]

@@AlexPlatacis thanks - I figured it out once I asked the question. Great idea. I will do the same. Are you going to make the blue tooth speaker fixed in place or portable.

[@AlexPlatacis]

@@ronwatson7888 We are planning a permanent installation. I will likely also install some power for that too.