MG MGB and MGB GT Tech Talk
With the battery on, I have no ill effects. When I turn the key the forth fuse (10amp) blows. I can still start the car. The head lights work. The interior light works and the oil pressure gauge works.
What does not work, or does not get power is:
Fuel gauge
Tach
Speedo
Temp gauge
Stereo
I assume I have a short somewhere but I have no idea where to begin. What do you suggest?
If it were me the first place I would look would be at the infamous hazard switch, It is on the same circuit as the fuel gauge, temp gauge, and tach. All those wires will be green. Someone may have tapped into that circuit to power the radio. There is normally a green and white wire that comes directly off the ignition switch that powers the radio. Look for that wire hanging loose. BTW that circuit(green) should be on the third fuse according to The Avanced Wiring chart. Good luck
I think you have multiple problems....and maybe some wires hooked up wrong at the fuse box.
The 4th fuse (bottom one) powers the purple circuit - horns, interior lamp, cigarette lighter, boot lamp. If that fuse is blown, those items shouldn't work.
The 3rd fuse from the top (green circuit) is the one for the gauges.
Speedo?? Do you mean the light? That's it's only electrical connection....and it's on the top fuse (red circuit)...
Stereo could be most anything if it was wired in by a PO. I've seen them connected to just about any wire that's handy. If it's factory (or wired correctly) it gets it's power via the ignition switch.
Mick,
I'd look where you were last working if indeed you were.
Stereo would be another easy place if you can get at the fuse without pulling the console.
If no luck try taking one wire at a time off the the output side of the fuse...bon't don't forget the third and forth fuse have that link at the back joining 3 & 4....If my memory is working today?
At the ignition (steering column) there is a purple/white wire hanging loose. Could that cause a short if it were touching something else in that area?
Mick,
Based upon pics you have posted...it cannot be fixed. Try no further. I will be down with a trailer and bring it back to NC. Just have the title available.
HeHe !
Chris
The dash is out as well as the stereo. When I switch the power on, the fuse DOES NOT blow. Would it be resonable to assume, that if I connect the dash wireing harness, but not hook up any switches, gauges or stereo, the only thing that would have power going to it is the gauge bulbs. If I then switch power on and the fuse blows, then the short would be in one of the bulb wires? If it does not blow, then connect the first switch or gauge and switch the power on and see what happens. Then continue with each switch or gauge until the fuse blows. Just trying to narrow things down.
No wireing under the bonnet has been tampered with during this time. Everything is as it was when everything worked.
The fuse in the Stereo appears to be good. I replaced it anyway.
I have Limey's modern fuse system with 6 relays and it is set up per his instructions. I'm certain that it is correct.
Chris, put your trailer on standby.
Mick
That would be my approach.....reconnect one item at a time until you find the culprit....
I hooked up the Brake Failure switch. No problem. I hooked up the Head Light switch and did not blow the fuse, however, when I turn on my Head Lights the gauge bulbs do not lite up. They should, shouldn't they?
If you have Limey's relay system and the new fuse system, you need to sit down with both the instructions that came with his kits and the advance wiring diagram for your car (sheet 17) so you can figure out what systems are common to the blown fuse. Given that you have the new fuse system, I can't help because I don't know how it's wired in, but taking some time and looking at the diagrams will save you a lot of time and enable you to get to the root of this a lot quicker. Right now you're just sort of shotgunning the problem and working on stuff that's well downstream of what is likely the problem. A little time spent studying the diagrams will save you a lot of time at the car.
Yes, check R-G wiring. Do parking and license plate lights work?[/quote]
Parking and License Plate lights work. Turn Signals do not.
Hate to ask this, but did it all work before you installed Limey's kit?
If everything works with the switch in the "on" position and the fuse blows in the "start" position it is obvious that there is a problem with either the start circuit or the ignition switch.
Print the appropriate wiring diagram ( http://www.advanceautowire.com/schematics ) and then highlight everything on the start circuit. Disconnect this circuit close to the ignition switch. If the fuse blows, it is the switch. If it doesn't blow, reconnect and disconnect at the next component downstream.
It is the Temp gauge blowing the fuse. Everything is now hooked up. One gauge or switch at a time and then tested. It is only the Temp gauge when hooked up that blows the fuse. Haven't hooked up the stereo yet but I will take care of what I know first. It looks like the Temp gauge wireing runs through the fuel gauge, which works, so I shouldn't have to go back anyfurther than that. What do you think?
It might very well be your fuse size - I can't remember whether you have Eric's fuse box or not. That might or might not make a difference.
That circuit that the temp guage is on - one side of it goes from the gauge to the temp sensor on the head. The other side goes to the fuel gauge, from the fuel gauge to the stabilizer, and the stabilizer gets its power from green wires. Just for kicks, unplug the wire at the temp sensor in the head, plug the gauge up, and see if it blows. If not, then touch the wire at the temp sensor to the block for a few seconds, taking the sensor out of the loop, and see if it blows. If not, then at least you know the gauge doesn't have a short in it, and you know the wire to the sensor is good. Then you can plug the sensor in and see if it blows.
We still may not know what your problem is, but you'll have done some more problem isolation.
I should have started out with this picture. I have mentioned that I have Limey's fuse kit but a picture tells a better story. The forth fuse down is 10 amp.
Following Johns kicks idea, I unplugged at the heat sensor at the head. When tested the fuse did not blow. Plugged it back in and tested and it still did not blow. WTF
It is hooked up now and nothing is blowing or going up in smoke. I did take the gauge apart just to look inside to see if I could see anything obvious. I didn't and put it back together. Do you suppose that just messing with it the short was undone only to give me trouble down the road? Should I get a new gauge?
This is where it gets hard, because you don't have any idea why its happening.
Another question - when the fuse was blowing, was the car hot or cold? The reason I ask is that when the car is hot, the resistance in the temp sensor goes down, increasing the current to the temp gauge circuit, which might increase the current enough to blow the fuse, especially if its close - I think. But, I flunked out of electrical engineering school so I may be all wet.
It's really a shame that Kimberly isn't around anymore. :(
Mick,
For what is worth I just looked at mine which is also from Eric, the 4th down is a 10 amp.
