Wire gage, fixes, and connection questions

[PeterLlo]

1977 Spider 124. Out of the blue, while working under the hood, smoke arises. The green and black plus brown and white wires in the harness connected to the 30 amp Bosch relay started smoking and melting (near each plug end) when I turned the ignition on to test my lights. I'd earlier converted all dash lights to LED, (except the alt. bulb) all worked then didn't, nor did the tach for that matter. I found a blown fuse and replaced it.

I had just finished working under the hood replacing the brake booster and MC, clutch cable, and fixing the cracked firewall. I thought the burning issue then could be a broken or dislodged wire. This led me to dig around on the Internet and forums. My thoughts were to do the brown wire fix, headlight, and wiper relay fixes all at the same time. I have the two kits.

While feeling around the starter wiring posts, the black wire ring connector broke. Question one, Could the degraded connection before its break have been the source of the above-noted overload to the relay harness? (Does anyone have a spare harness they'd like to sell?).

Question two, with the black wire needing a fix, I decided to run fresh brown, black, and red wires to the starter cutting the three before the starter harness plug and eliminating that altogether. There was a lot of oil and grim down there. It appears the red and black wire is 8 gage and the brown, is 10, is that correct?

Question three takes me back to the relay kits. Should I connect power for each of them the to primary starter post with the other three? Alternatively, can I connect them to what appears to me, as the unused secondary post?

Question four. There seem to be two camps on the brown wire fix. At the end of the day is doing it a benign thing that may, or may not, help but will not hurt? I did pull the ignition out and all of the wiring and plugs are in great shape, with no burns, discoloration, or cracks.

This car seems to take a perverse pride in adding seemingly unrelated problems as I go through it, quite an education.

[spider2081]

While feeling around the starter wiring posts, the black wire ring connector broke. Question one, Could the degraded connection before its break have been the source of the above-noted overload to the relay harness? (Does anyone have a spare harness they'd like to sell?).

First I would not make any changes to the cars original wiring until the overheating wires issue is corrected. Modifying a cars wiring makes it very difficult for future trouble shooting. Anyone trying to assist you would most likely be looking at the original wire diagrams for the car. If it has been changed there probably is no diagram to follow.

I think the black wire at the starter solenoid connects the alternators output to the starter solenoids battery terminal. When the engine is running the alternator's output powers the cars electrics and charges the battery through this wire. When the engine is not running this wire puts battery voltage on the alternators output post.

I don't think this degraded wire condition contributed to your over heating wires at the relay.
Note: Judging from the wire colors ( green/black and brown/white) I think the relay in question is the ignition control relay. Its function is to select which set of ignition points the engine should be running on. Does the distributor still have 2 sets of points in it?

I am not a big fan of the "brown wire fix" for the most part its bypasses C19 a 3 cavity connector located on the driver side fender well under the hood, near the charcoal canister. The connector has a red wire and a brown wire in it, one cavity is empty. The brown wire brings battery power to the ignition switch and the red wire powers the starter solenoid when the ignition key is in the "start" position. The connector often becomes intermittent contributing to the infamous "click" when trying to start the engine. Cleaning and tightening the connection usually cures that issue.

Hope this is some help

[PeterLlo]

Thank you for the input. I agree wholeheartedly about the wiring changes. While I do have those kits, my install plan would be to do that after I get this issue fully resolved, and one at a time at that.

With regard to the wiring, the only changes I have made are to cut out previous damage and replace sections of the wiring where necessary. To keep the color circus to a minimum I'm using the same color for the replacement. I figure that way one can find the original color wiring and trace from there. I've cleaned and renewed almost all the grounds as well. I pulled each relay one at a time and cleaned up the contact prongs and reinserted them.

The PO owner had some work done to the car including paint, the wiring looms weren't covered so I've spent time removing silver overspray. A stereo was added with crappy connections. All I have done there is redo those weak connections with sharing wrapped butt connectors. Then I sorted out the bird's nest he left under the dash. I just found a brown wire that is disconnected from the fuse box and has been spliced with a black wire leading to the new stereo. So I am not sure where exactly that needs to plug into the fuse box.

The car does retain its dual point distributor. The two condensers attached to the distributor have one wire running into the passenger compartment, one is green, and the other is green/black like the burnt wire. I wholly admit I am a neophyte here. How does one test a relay?

[spider2081]

I think you might find joining Mirafiori.com helpful. There is a library available to members that contains most wire diagrams. I would print out the wire diagram for your car and use it as a reference while trouble shooting.

[18Fiatsandcounting]

The car does retain its dual point distributor. The two condensers attached to the distributor have one wire running into the passenger compartment, one is green, and the other is green/black like the burnt wire. I wholly admit I am a neophyte here. How does one test a relay?

The dual point distributor setup is complicated and prone to issues so many owners end up converting the system back to a single set of points. In a nutshell, here's how it works (if not modified):

There are two sets of points, each with their own condenser (capacitor) across them. There is the primary set of points which uses the green wire, and there is the secondary set that uses the green/black wire. The secondary set of points provides an additional 10 degrees of ignition advance when the engine is cold or is being restarted when warm. The ultimate need for all this was to meet increasingly stringent emissions laws in the mid to late 1970s.

Depending on model year, the selection of which points are in use (primary or secondary) is made by an "ignition mode relay" which is usually in a tray under the glovebox. The ignition mode relay gets its signals from a temperature switch on the bottom of the intake manifold and, depending on model year, a signal from the low oil pressure light circuit.

Setting ignition timing on dual points can be tricky because you have to make sure that you set the timing while on the primary points (green wire). If any wiring has changed or the ignition mode relay is stuck, you can end up setting the timing on the secondary points which then causes the engine to not run well when it does move back to the primary points.

As for how to test a relay? It depends on the relay's function, but most are simple switching relays, so if you apply 12 volts across the two terminals for the coil inside, you should hear it click. Sometimes (but not always) the relay terminals will have an 85 and 86 designation next to them which are the terminals for this activating coils. Note that relays don't go bad that often although their contacts do deteriorate with age.

-Bryan

[PeterLlo]

Thanks for all the input. Right now I'm getting the breaks sorted and will return to the wiring issues after. I've been off the forum a bit, working to support the habit.