Idle stop solenoid wires red hot

[MarcusFedler]

So. I got the itch to start the car and get it ready for spring. Started up after a few turns and idled nicely. Then smoke poured out of engine compartment. Shut car off popped hood and found the two wires to idle stop fried pretty good. I would assume some sort of short in the sensor itself. Car ran a bit rough at first but just started after 4 months sitting not sure it was that rough.

Thoughts on repair?

[Nanonevol]

Odd that it would fail - maybe a short somewhere? If it's fried I'd say replace it.
I store my car for winter also and usually have to run around a bit to get the bugs out.

[MarcusFedler]

Further diagnostics show pink wire to solenoid fried. The 2nd wire to ground was also fried. After locating that wire it was not connected to ground. It must have been disconnected when I replaced the alternator last fall. I traced the pink wire back into the wiring harness until there was no indication of heat damage. I assume there would be no problem rerunning the pink from there with a new wire to ground. Thoughts?

[spider2081]

Have you looked at the wire diagram for your car?? I assume you have a 1978 Spider. I am reading the 1978 wire diagram in the mirafiori site There isn't a pink wire on the idle stop solenoid. There is a pink wire on the thermal switch for the ignition mode relay. This pink wire originates at Fuse 1 and is power to the switch. The idle stop solenoid should have a gray/red wire on it and a ground wire on it. If the cars ignition system has been modified and it no longer has dual points someone may have connected the pink wire to the idle stop solenoid at that time. If the car has only one set of points it does not need the ignition mode relay circuit. It still need the idle cut of solenoid circuit.
The idle stop solenoid needs to have power on one terminal ( when the ignition switch is in the run position) and ground on the other terminal all the time.

[MarcusFedler]

It's definitely pink. It was a bit confusing at first because the wire had no insulation on it. But as I look through is definitely pink. I don't know what the color of the ground wire was because it's completely bare now. I did see the wiring diagram have gray red and I don't have a record from the P.O. about any modifications to the wiring being done. He owned it twice but has been the main owner for most of its life with meticulous records. Most of which are routine maintenance. Very little mechanically had been done to this car since it only has 77k miles on it. Of course now that it's getting used things like this are bound to pop up.

[MarcusFedler]

The pink wire definitely went to solenoid. Not sure about rewrite but i did see the wiring diagram show gray red. So there must be some modification. I ordered a new solenoid and haven't received it from Vicks yet. Once I can replace the solenoid I'll know for sure. What I have done is rewired the system back to untouched insulation to rule out internal resistance. From that point back still gets hot. So either the entire wire is bad or the solenoid. I'll need to replace the solenoid before rewiring back further. I'll post update after solenoid. Any confirmation on my troubleshooting would be appreciated. Thank you!

[spider2081]

First I am not clear on what you are saying about the ground connection relationship to the pink wire. The pink wire should not be connected to ground. The pink wire is power to the solenoid.
On another thought. for the pink wire to overheat and melt I would question the value of Fuse 1. It may have been replaced with a fuse of a higher current rating then belongs in that position. I am guessing Fuse 1 should be an 8 amp fuse and the only 16 amp fuse would be for the horn circuit. A circuits fuse should blow before a wire protected by it melts.

[MarcusFedler]

As it turned out, the previous owner at some point removed the Ignition Mode Relay Thermo Switch. So the Pink wire came into the switch and went out with Gray/Red to the Idle Stop Solenoid. The Blue wire from that and associate blue black from the same circuit was tied back into the wiring harness. If I would have followed that first, I would have recognized it immediately. I mistakenly recreated the pink - Gray Red wire and sent the 2nd line to ground. (It didn't make sense to me either but I didn't clearly understand the wiring diagram and was working with a lack of information. I'm somewhat newbish when it comes to wiring...)

When the alternator was replaced, I must have jiggled the gray/red wire out of the tied back harness and the connector end touched ground. It burned up to the point where I couldn't tell what the color of the insulation was. When I recreated the wiring as it was, I should have left off the jumper gray/red and didn't. It was a bone head decision that I realize now WAS stupid and should have trusted my instincts initially.

So, the pink wire should have gone to the solenoid and the engine block created ground. Like I said before, it seemed stupid to me, but for some reason I though it needed a ground just because of the way the wiring was cobbled up. Thank you for your help!

[spider2081]

The wire diagram shows the pink wire protected by fuse 1. If fuse 1 is the proper value your wire should not have melted. The fuse should have blown. It would blow every time you replaced it until you ungrounded the pink wire.
I really think you need to check the value of Fuse 1 and check to make sure the pink wire is being protected by the proper value fuse.

[MarcusFedler]

Will do.