81 Fiat Mystery Wires

[searya]

I am reinstalling my dash components and have a few left over wires

Anyone know what the wires in the picture are for? These are below the main dash near the radio.

https://drive.google.com/open?id=1IDiQC ... QoE_Yy_JnZ

https://drive.google.com/open?id=1IDiQC ... QoE_Yy_JnZ

colors are Red with black dashes coupled with Red with Black stripe, Dark Blue with violet stripe, Light blue with White stripe. All end in female spade connectors.

Thanks,

Sean

[RRoller123]

Those are pretty unique wire colors, the schematic should show not only the colors but the connection type at the end, no help there?

[GeorgeT]

Possibly wiring for power windows, I think the cars were prewired for them.

[spider2081]

I think the radio power antenna switch has red/black wires bringing power to the switch and light blue/white & Dark blue/red wires going back to the power ant motor driver side in the trunk. The trunk end of the wires would be behind the side carpet forward of the gas fill door. There are 4 red/black wires 2 are for the antenna motor switch. One of the red/black wires comes from the hazard switch and one red/black wire goes to the courtesy light assembly.

[rridge]

I was looking at those same four wires hanging down from somewhere in the vicinity of the relay tray under the glovebox today. I'm installing a new radio and was poked around looking for the factory wiring. The aftermarket radio installed by the dealer in 1981 bypassed the factory harness and created a birds net of extra wires behind the upper console.

As Dave says the factory schematic clearly show these four wires as the inputs and outputs from a power antenna switch. I can find the two blue wires in the cable bundle running along the driver's floor between seat and rocker panel along with the rear taillight harness and disconnected seat belt buzzer wires. But the schematic does not show the switching circuit or hint at its location.

Right now my power antenna in the driver side rear fender is powered directly from the fuse panel with a second wire bringing a power signal to the antenna's own relay switch when the radio is on. The antenna finds its own local ground in the rear fender. I don't see why there would be a separate power antenna switch and I don't see where it would sit but I have not dropped the relay tray or removed the glove box to look for it. Nor do I understand the circuit logic.

[spider2081]

I don't see why there would be a separate power antenna switch and I don't see where it would sit but I have not dropped the relay tray or removed the glove box to look for it. Nor do I understand the circuit logic.

I think many of the car radios available in the 70s and 80s did not have a switched power output to control the power antenna. The separate switch was needed for power antennas to be installed with these radios. These power antennas needed power polarity swapped similar to a power window to be driven up and down.
When car radio manufacturers included the switched power output to control a power antenna or power amp the power antenna was redesigned so it automatically went up when radio turned on and came down when radio turned off. This design means the antenna is either full up or full down. The older design allowed the operator to determine how far up the antenna traveled. It also did not automatically go down when the car was turned off. The switch had to be activated to bring the antenna down.

[rridge]

Dave, you got it. There would have been a physical switch mounted somewhere below the radio, perhaps in a modified courtesy light. I found a full description on p.56 of the 1980-81 Spider 2000 Electrical Diagnosis Manual. The switch circuit looks a lot like a power window switch. Inside the switch case were two individual switch throws that reversed the polarity of the power using the two blue wires to change direction. Power was from the red/black wire that through the jumper continued to the courtesy light. The ground was through the switch case itself. When the "up" line was powered, the "down line" was switched to ground and vice versa. The power got to the rear fender via the rear harness. The switch wiring connected to the rear harness at a twelve pin connector under the steering column, connector C-18.

The Electrical Diagnosis Manual can be downloaded as a pdf form Mirafiori library. You must be a registered Mirafiori user and have signed in to use this link: https://www.mirafiori.com/forum/viewtop ... 41#p511878

[spider2081]

The Electrical Diagnosis Manual

There are a lot of negative opinions about Fiat electrical. I find their "electrical Diagnosis Manual" is one of the most comprehensive Automotive publications published. I think every Spider owner would have a more reliable drive if they spent a few hours reading this manual. Just an opinion