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Fried my Rear harness

PostPosted: Sun May 22, 2011 9:26 pm
by sg18438
I just got my car back from the painter"s ('61 Bugeye)...I am reinstalling all the lights,etc. Re-hooked up the tailights, rear turn-lights and license plate light. I did not connect the front harness to the rear. I thought I'd try out the lights I had installed and turned the ignition on and activated the left and right rear turn signals (they both worked)...however, I immediately smelled cooking wires and saw smoke coming from both the rear harness near the gas tank filler tube and on the firewall near the rubber grommet. I unhooked the battery and surveyed the damage...I'd fried the insulation off the (ends only) of all the red "hot lead" wires (4 wires).
What happened? What have I done wrong? Thanks, Steve G

Re: Fried my Rear harness

PostPosted: Tue May 24, 2011 1:44 am
by Charlie Tolman
I have looked at the wiring diagram for the Sprite I, and found the red (red only) wires in a few places.

From: Ignition and lighting switch, post S.

To: Right and left tail lights, and license plate light.
To: Left and right side lights.
To: Panel (dash) light switch. This switch then connects to the cigar lighter, dash light, speedometer light, and tachometer light, through red-white wires.

One (or all ?) of these red wires must have been grounded, or one (or all ?) of the red-white wires were grounded if the light switch was in the "on" position.

Charlie T.

Re: Fried my Rear harness

PostPosted: Tue May 24, 2011 10:07 pm
by sg18438
I went through the entire harness today.(soldered my little heart out) The short was clearly in the lighting circuit... based on level of damage I'd guess the hot lead (red only) into the license plate light was somehow grounded...it's tied into the tailights and turnsignal lights front and back. I've decided to put a couple of inline fuses into the lighting circuit. Plus I've ordered a mini fuse panel from Moss. Tomorrow I'll rehook-up all the lights and see what happens. Thanks for the input. Steve G.

Re: Fried my Rear harness

PostPosted: Wed May 25, 2011 12:04 am
by hoggie
Can't remember where I read it, but a good idea to use when resolving wiring problems is to insert a temporary fuse between the battery terminal and the battery cable. I think a 10 amp would be safe. Then you will blow the fuse instead of burning wire.

Re: Fried my Rear harness

PostPosted: Wed May 25, 2011 12:39 am
by Charlie Tolman
The four turn-lights are not on the same circuit as the tail lights and license plate light.

Power is fed to the fuse block via a white wire, then to the flasher via a green wire, then to the turn-light switch via a green-brown wire, and then to the two sets of turn-lights via green-red and green-white wires.

My circuit diagram does not show a fuse in the tail light, license plate, etc. circuit. Strange !
This might explain how a grounded hot (red) wire did not blow a fuse.

Charlie T.

Re: Fried my Rear harness

PostPosted: Fri May 27, 2011 6:00 pm
by sg18438
Well guys, I re-wired, repaired and sorted out everything I could. I re-layed the harness in the car and put an in-line fuse (15A) between the battery and an the unhooked positive battery cable and turned the key on...whalah! everything worked.
I had previously found what I believe was the offending short, it was in the license plate light set-up, it was an original Lucas piece and it was fried to the extent that the metal contacts had eroded away.
Thanks for all the help, the inline fuse idea was great...

Re: Fried my Rear harness

PostPosted: Sat May 28, 2011 12:33 am
by Charlie Tolman
It is nice to hear "positive" results on the electrical re-wiring.
Mike's suggestion, regarding a temporary fuse at the battery, is very good.
Adding a few inline fuses is another good idea, especially one in the tail-light and license plate wiring.

Charlie T.