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Popping my mind and a 50amp fuse

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K

kkaa

Jedi Hopeful
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Guys -

Need some help. The second i turn on the key, i blow instantly my 50 amp fuse. Little background, new restoration, negative ground, all worked perfectly until i burnt the headlamp/dimmer switch. Headlamps are on a Lucas relay setup and now with a new switch work perfectly. High, low, all works, but again, the 50amp blows instantly.


Originally i thought it was my horns, replaced them with new, but again no luck. Put in a new flasher unit, no love. Any help on how to troubleshoot would be greatly appreciated, someone in NH willing to come by and help would be awesome....

Kurt
 
I would disconnect everything at the fuse box except the white wire from the switch and see what happens and put them back one by one has to be a wire that got cut and shorting out .Check the wires on the dist and the cut off switch
 
rjc157 said:
I would disconnect everything at the fuse box except the white wire from the switch and see what happens and put them back one by one has to be a wire that got cut and shorting out .Check the wires on the dist and the cut off switch
Click to expand...

This is an excellent way to locate the problem.
 
Hi Kurt,

when referring to the 50 amp fuse, I trust you have not replaced it with a SAE 50 fuse as the original designation refers to a UK 50 amp fuse measured differently and is closer to an SAE 35 amp. As this fuse is quite powerful, your original horns could have had a short and may have fried the harness in the process of failing.

Power is passed to the non-switched “Hot” side (1 and 2) of the fuse block directly from the battery circuit with drops at the starter solenoid and regulator. If the fuse block is not faulty the power feeding the Hot and Switched sides of the block should be isolated from each and circuits/device faults causing a fuse failure should remain isolated to the side from which they are powered from. This being said, your fuse failure, should be caused by issues and problems in circuits and/or devices being fed by the Hot side of the fuse block and cause its fuse to blow every time the Master Battery Switch is turned on. The Ignition/key should have no affect on blowing this fuse. However, since you have indicated that the hot-side fuse only blows when the ignition/key is turned on, you must consider the probability the hot side of the fuse block is now providing power being sourced in some way from/through the ignition switch and the Hot side of the fuse block is no longer present.

At this point, and since only the larger fuse is blowing, I would begin to probe the circuit and devices fed from the #2 set of connectors on the block and protected by the faulting fuse. Your horn circuit is the only thing officially positioned to receive power through this fuse, however, you may have attached other components to this power source during your recent restoration and conversion. I would also suggest you determine why the HOT side of your fuse block does not exist and correct or understand why you want to keep it that way.

Good luck,
Ray (64BJ8P1)
 
Holy smokes, DUH! I thought about this way too hard, what a simple answer and will do it tonight!!! Thanks guys for the plan, and tonight will do exactly what your recommending. Ray, yes, bought the proper fuses from AHspares, and 10 just in case, HA! I was super nervous thought when it popped, thats a huge amount of power.

The thing that makes me nutty, the kids and I went over the top protecting the headlamps with the relay unit from moss, added in-line fuses for wipers, fuel pump, blower, and OD, now this!!! Ugggg!!!!!
 
For testing purposes get yourself a circuit breaker from Radioshack or similar to put inline in place of the fuse.
After you have blown 10 of the fuses just testing they start to get expensive.
I use my 'breaker for all sorts of troubleshooting all of the time.I have leads and alligator clips on it to make it easy to use
BillM
 
Billm said:
For testing purposes get yourself a circuit breaker from Radioshack or similar to put inline in place of the fuse.
After you have blown 10 of the fuses just testing they start to get expensive.
I use my 'breaker for all sorts of troubleshooting all of the time.I have leads and alligator clips on it to make it easy to use
BillM
Click to expand...
another source for circuit breakers is a parts dept for semi trucks, Kenworth, Peterbuilt, etc,. They use auto resetting types.
 
kkaa said:
Holy smokes, DUH! I thought about this way too hard, what a simple answer and will do it tonight!!! Thanks guys for the plan, and tonight will do exactly what your recommending. Ray, yes, bought the proper fuses from AHspares, and 10 just in case, HA! I was super nervous thought when it popped, thats a huge amount of power.

The thing that makes me nutty, the kids and I went over the top protecting the headlamps with the relay unit from moss, added in-line fuses for wipers, fuel pump, blower, and OD, now this!!! Ugggg!!!!!
Click to expand...
I added a Fuse panel from Charlie Hart for my BJ8. It handles 6 fuses. He has them for the earlier Healeys that has 7 fuses.
 
Cant believe it :highly_amused:!!! We found our problem. If you like a challenge dont look below, just at these items we used. The answer is below...
photo (2).jpgSCH1.jpg






Yup, the fuse box is upside down in comparison to the diagram, so we had our fuses in the wrong spots!! It took my middle son to say "dad, the wiring is right if you flip the sheet"!!! The only weird thing, the 50 was on the bottom and popped. Why, i have no idea considering the 35 in there now doesnt.. Any idea why or should we worry? The only thing now not working is the flashers. I hear it engage when the key is on, but no blink. Does the car need to be running?
 
Last edited:
kkaa said:
It took my middle son to say "dad, the wiring is right if you flip the sheet"!!!
Click to expand...

Out of the mouths of babes! Car doesn't need to be running for flashers, but key must be on. First suspect is the flasher can. Have you done any "upgrades" like LEDs for the flashers as that can have an effect if you're not using the appropriate flasher. Also check to see if your bulbs are properly installed. Check the wiring, look for unplugged leads, particularly coming out of the bottom of the stator tube. And last, but not least, the contacts in the control box may need to be dressed if it's been sitting for years. That requires a special contact dresser, not a file, but I suspect that's the least likely of your problem
 
Thanks Rick, let me check, or should I ask Avery, ha! Ill let you know how we make out...

HealeyRick said:
Out of the mouths of babes! Car doesn't need to be running for flashers, but key must be on. First suspect is the flasher can. Have you done any "upgrades" like LEDs for the flashers as that can have an effect if you're not using the appropriate flasher. Also check to see if your bulbs are properly installed. Check the wiring, look for unplugged leads, particularly coming out of the bottom of the stator tube. And last, but not least, the contacts in the control box may need to be dressed if it's been sitting for years. That requires a special contact dresser, not a file, but I suspect that's the least likely of your problem
Click to expand...
 
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