• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Blowing 15A Fuses as soon as I apply the brakes

Share this page

Jim_Gruber

Jim_Gruber

Yoda
Country flag
Offline
So I am trying to get Bugsy's Brake Lamps Working. The one consistent thing is as soon as I touch the Brake Pedal I blow a 15 Amp Fuse. A little worried about upping to a 20
Amp Fuse. I'm only lighting two 1156/57 bulbs. It cannot take that much current to do that. At this point I have changed out one of the tail lamps to a new tail lamp. Could be I have a short back there but the driving lamps work fine. Thoughts gents on an all of a sudden thunderstormy Friday night in Dayton, OH . Can she take a 20 Amp Fuse Captain or will I let the smoke out of the harness.
 
You have a short... period. A bigger fuse will also blow or if not, burn up some wiring. Since power is supplied to the switch from the switched side of the fuse block (green wires) I would check/trace from the brake switch (green/purple tracer) to the stop lamps bulbs first. Maybe you attached the ground (black wire) at the lamps on the wrong terminal. Use an ohm meter or a test lamp.
 
So with my trusty Radio Shack VOM I am showing about 50 Ohms Resistance on the switched side of the fuse box. Wires back at the new tail lamp don't show any physical signs of touching, I cleaned up these terminals. Oh wait a minute the SU Fuel Pump is tied to these same terminals but I reused the same connection point to switch from an old Bendix to the SU. Hmmm that is additional load and I do have a 10 Amp inline fuse going ot the SU. I could switch the fuel pump feed to the other side of the switched feed at the fusebox. Thought if anyone is on here tonight.
 
Gerard, Again you assume I can tell any wiring colors as the cloth harness has either all turned to the same color or I'm left with the inside black wire. So your idea has merit and since I am shown 50 Ohm where there should be none I'm betting you are correct and I have wiring switched back at that turn signal. Back to the garage to puzzle it out.
 
Fixed it. Thanks Gerard. I had the correct wires on but one of those itty bitty wires was touching in the wrong place. I now have brake and tail lamps pending a change of the other tail light fixture but at 10:45 PM that's a battle for Saturday PM. Thanks Gerard for the help.
 
Yep, gotta watch for that; all it takes is one strand. Glad you found the source of the short.

As far as IDing color codes, if you still have the cloth coating on the wires, and they are unreadable, you can trim back some of the cloth bundle wrapping a little ways to where it has not had exposure to atmosphere. Colors should be intact in the previously unexposed areas. You can then label the wires with some color coded shrink wrap or some of those adhesive number labels. Label both ends and you'll have a way to easily identify wires in the future.

Jim_Gruber said:
Fixed it. Thanks Gerard. I had the correct wires on but one of those itty bitty wires was touching in the wrong place. I now have brake and tail lamps pending a change of the other tail light fixture but at 10:45 PM that's a battle for Saturday PM. Thanks Gerard for the help.
Click to expand...
 
Jim,
Ive got my original wiring harness with the sub harnesses if you want them...some of it is butchered, but most intact.
Rut
 
Back
Top