'81 put in reverse and fuse blows

[rjkoop]

So I looked at the '81 Fiat artigue wiring diagram and the colors don't match at all. But this looks like original wiring. It doesn't look like a hack job at all.

Primary connector from wiring harness on driver's side...


Another picture of the driver's area...


I've got light green, blue/black striped, white, black, yellow/black lines, red, yellow/red lines.

According to the diagram it should be black, white, red, light blue/black, light blue, yellow/black, yellow/red.

Not sure what to make of it. I'll look at the other diagrams and see if something matches closer/exact.

And the driver's side works perfectly. So maybe I should worry too much about the colors. And just trace it through to the other side.

I did another test as well. I disconnected the main connector on the driver's side, touched the ground post bolt and got connectivity on all but 1 of the wires on the main connector that comes from the hiring harness to the driver's light fixture. Does this make sense? I thought from the ground post to the wires I should only see the black one have connectivity with the ground post. What am I not understanding?

[aj81spider]

Can't help you with the colors. However you should see ground through all the wires (with some resistance). You are basically connected to ground through the bulbs. The wires turn on the bulb by applying power at that connector you are measuring at. With the connector disconnected you are looking into the bulb connected to ground. The only resistance will be the filament of the bulb.

If you turn the voltmeter to measure ohms you should see some resistance to ground. I forget what the current draw on the tail lights are, but as an example, if the bulb draws 1 amp then the resistance will be about 12 ohms.

[spider2081]

Checking for shorts in a car's light circuits with an ohm meter is very difficult because there are so many lights in parallel. When you check from the rear connector say tail light to ground, you are measuring the total parallel resistance of all the remaining bulbs in the circuit. That would be at least the 2 front parking and side lights. If each were 20 ohms the parallel total for the 4 would be 20/4 =5 ohms.

Colors feeding drivers side from my 80-81 Fiat Diagnostic Manual

White: Back up
Red: Stop light
Lt Blue/Blk Left turn
Lt Blue right turn
Yellow/Red left tail light
Yellow/Blk Right tail light
Blk Ground

I think your problem is most likely to be in driver side PC board. The ground from the feed connector is not getting to the output connector for the passenger harness.

[rjkoop]

Great info once again. Thanks. Of course even if the rear connectore is disconnected the fronts are still connected. Makes so much sense once I get the xplanation.

[rjkoop]

Post deleted. Sorry.

[rjkoop]

Richard, I have extra tail lights if you are interested in swapping them to see if that is the issue

Jay,
Used new board that you loaned me and works perfect. All lights on driver's and now passenger's side work perfectly! I cleaned, dremeled the connectors and light sockets and sprayed with electrical cleaner and I've got bright reverse, blinker, brakes and hazard lights. Thanks goes to Jay, my local Ottawa parts guy!

Richard

[4uall]