MGB-GT 1974 GT fuse box layout

[BoneIdle]

Greetings all!

Work on the GT was suspended for a while due to a death in the family, but now I'm back at it.

I've had a problem with the battery draining totally to nothing for some time now. I had assumed that the battery had finally exceeded its service life, so I replaced it.

Although the old battery did test bad, the problem has recurred with a brand new battery.

Finally, I got off my lazy posterior and hooked up a test light between the positive battery post and the cable. I ensured that the key wasn't in the ignition and observed that the little test light was glowing.

I began pulling fuses, one at a time, and the light finally went out when I pulled the bottom fuse in the fuse box.

I can't find the cover for the fuse box, and I'm not sure that it would have this information on it, so what does that particular fuse control?

I tried a search on here, but I got bogged down pretty quickly, so I figured I'd just ask.

I do have a very good manual somewhere, but I'm still trying to locate it. When we moved from Iowa, the movers packed things too well.


Thanks. It's good to be back.

Garry

 

[DrEntropy]

Hi Garry. What are the colors of the wires goin' thru the fuse in question?

 

[BoneIdle]

Looks like brown and gray ( or tan). I'll have to get a better light source going to be sure.

 

[BoneIdle]

Well, it's the brown wire that's causing the problem. I pulled that one from its connection and the light went out.That narrows it down somewhat.

 

[BoneIdle]

Gee. It looks like I'm back to the original suspect: the hazard flasher and/or hazard flasher switch. Now if I could only figure out where the flasher is. It's definitely not next to the turn signal flasher.

 

[JPSmit]

Just looking at this diagram

https://www.advanceautowire.com/mgb.pdf

looks like there should be three brown wires

1.one to seatbelt buzzer etc.
2.one to starter relay
3. one to ignition, headlights and hazard relay.

If you have isolated it to the 3. above, and likely the hazard flasher. If there is any comparison to my Midget, one flasher is by the hazard switch behind the dash and the other is attached to the firewall above the glovebox.

FWIW any cheap autozone/harbor freight flasher will work

 

[BoneIdle]

"Wanna see something really scary?"

I just pulled the console. The flasher may or may not be good, but for future referencen a 1974 MGB GT, the flasher is mounted behind the console on the driver's side. It's pretty low down - just above the transmission hump.

The scary part was the stereo. It was ( and still may be) a very nice Kenwood, but the way it was connected...

Anyway, I snipped the black wire ( stereo side) and the test light went out. I haven't had a chance to trace down the wire, but that stereo is coming out for the time being.

More later, and thanks for the replies!

Garry

 

[DrEntropy]

I was at a client's place when I replied, just got back to th' hovel.

That brown set of wires will be hot at the fusebox, they're supply side. You likely found your draw tho.

 

[BoneIdle]

Yeah, Doc. It looks like it was a combination of the radio and the flasher. After snipping the wire, I plugged the flasher back in and the light came on.OTOH, it could be the flasher switch is permanently on. I'll know more once I completely disconnect everything and put a meter on the switch to check for continuity.