Greetings dear people...

It has been a while since I have posted. The project at hand is a 1977 MGB roadster that returned from the body shop a while ago. Among the goodies that had to be accomplished after the body shop was done with the car was the re-attaching of various wires, including replacing a broken fuse box.

Now, I am not so dumb as to simply pull all the wires from the box without labeling and / or making a one-to-one replacement. Obviously, however, the last person so to work on the box was not so careful -- trust me, it was horrid.

So, I've purchased, read, and marked the marvelous book on MGB electrical systems, well worth the $40 from Amazon. I've also downloaded and exploded the diagrams from Advanced Auto Wire (may they be glorified and highly blessed forever and ever for making these available). I've even worked with the diagrams from the Bentley and Hayes manuals.

I can't find the two brown wires that are supposed to attach to the bottom fuse on the fuse box. They seem not to be anywhere near the wiring harness. I also seem to be missing the white wire that goes to the third fuse and provides power to the green circuits (guages, tach, etc.).

A picture may be worth a thousand words. Might some kind person with a similar automobile provide a picture of:
1. starter relay mounted forward of the fuse box,
2. fuse box with the cover removed.

BTW, the car runs after I replaced the fuel lines and put new points in the fuel pump. The rear lights work, the fronts are not yet connected.

The DPO did do a lot of bodging on the electrical system, this is quite apparent. I am thinking unkind and un-Christian thoughts about him, which is not good for he committed suicide about 10 years ago and I am a Lutheran pastor. Any help you may render so to put his soul at rest and to help me forgive his mechanical ineptitude would be greatly appreciated.

Many thanks.

jeff williams - cfiaime

Some '77s were fitted with an ignition relay. If your car has an ignition relay, use the diagram for '78 and later. With an ignition relay, the white wire does not go to the fuse box. The ignition relay looks just like the starter relay.

Make sure you orientate the fuse box correctly. Pins 1 and 3 on the fuse box should have continuity. If you install the box upside down, the car won't turn off and the marker/tail lights won't work on one side of the car.

Make yourself a couple of enlarged prints (I printed out the diagram for my car on four sheets of paper and taped them together to make a diagram 14"x22") of the wiring diagram, one for reference, and one to make notes and keep track of your progress. Make notes of any changes that were made.
Start at the starter and verify the connections. Methodically go through the wiring in the engine compartment and check off each connection after you have verified it is correct.

The Lucas relays in my car are not labeled the same as the wiring diagram. Below is the pin conversion chart

Starter relay

W1 - 86 - white/red wire from the ignition switch
W2 - 85 - black wire connected to ground/chassis
C1 - 30/51 - brown from the starter
C2 - 87 - white/brown going to the starter. Note this wire is mismarked as a brown/white wire on the Advance drawing.

Ignition relay

W1 - 86 - white wire from the ignition switch
W2 - 85 - black wire connected to ground/chassis
C1 - 30/51 - brown wire from the fuse box
C2 - 87 - white/brown going to the fuse box.

Greetings...

Thanks for the information.

My car seems to be near the middle of the serial number range for 1977 (432618), so I wonder if it would have the later electrical system. Ah, something to look for.

Again, I truly appreciate the information.

Greetings again...

My car does have the ignition relay, so many of my questions are answered. Now if I only had time to work on the car, but with a wedding this weekend and a funeral on Tuesday, I'm afraid the MG is low on the priority list.

Ah, the joys!

Geez, Jeff! You need a "Second in Command"!!! Don't these people know you have an MG to get running?!?

Honestly, the Advance charts and a bit of "quality time" and you'll have it sorted. The later cars were 'overburdened' with modern improvements IMO... Just another reason to abandon the DIY fix and wheel it to a dealer.

Simply remember: You are SMARTER than the car!