V1 Mystery Wires

[DUNE]

Hey everyone!
Manitoba weather is finally getting nice enough to make some serious headway on my donor and after a couple evenings of tinkering I am almost ready to drop the powertrain! The only thing I have left to do is identify 2 mystery wires that I have going from my engine/headlight harness to the main harness that I am unsure of. For context, I have the 2009 turbo SS.

Wire #1 (First Picture)
Spliced into my headlight harness, there is a green and black wire that connect to what looks to be a relay which is in turn connected to the main harness that goes into the cabin. My current best guess is that this runs to power the amp when the ignition is turned on? The black wire is grounded and the green taps into one of the front headlights. Can anyone confirm before I start cutting wires?

Wire #2 (Second Picture)
This second wire I am more unsure of. It is a single purple wire tapped into the cylinder 3 spark plug and running back through the firewall where it disappears. Does anyone know what the purpose of this wire might be? Its currently my last wire connecting my engine and body.

 

[Gtstorey]

Add you donor to your signature. There are differences in the wiring between them.

Not sure anyone is going to be able to say what the splice is in picture 1. If connected to headlights, maybe they had other lights powered by the relay. However they may have had a bad stock relay, and are using this to power the OEM headlights. Need to identify the pins the wires connect to and see which side of the stock relay they are on.

What's the color of the oem wire the additional coil wire is attached to.

 

[RCK605]

Do you have any aftermarket gauges like a tach or shift light? They could have possibly tapped into the coil to get RPM.

 

[DUNE]

The purple coil wire disappears through the firewall and I haven't been able to track down where it connect to OEM wiring yet. Maybe ill have to do that before dropping the powertrain
There doesn't appear to be any aftermarket gauges. Just the factory boost pillar gauge

 

[Gtstorey]

What color wire does the purple wire attach to in bundle by the coil?

It's possible someone had a bad 12v+ wire feeding the coil break and they powered it with something else. Or they might have added a ground.

Most likely is aftermarket tach or shift light though.

 

[DUNE]

What color wire does the purple wire attach to in bundle by the coil?

It's possible someone had a bad 12v+ wire feeding the coil break and they powered it with something else. Or they might have added a ground.

Most likely is aftermarket tach or shift light though.

Its connected to a light blue/green wire running into the spark plug.

While looking at that one I also found another purple wire coming out of a different engine multi-plug, pictures are below. This one is the same deal where this spliced in purple wire runs into the cabin. Are there wiring diagrams for these plugs that I can reference?

 

[Gtstorey]

Technically, that isn’t running to the spark plug, it’s running to the coil. Light blue/green iisn’t a choice of colors for the coils on the later
models, just light blue for coil 3 or dark green with white strip on coil 4. These are the fire signal for coils so likely was aftermarket tach.

Im not aware of any free wiring diagrams for the later models. You can subscribe to Alldata or buy the service manuals. I

 

[Gtstorey]

You need to show the end view of a connector for good if. It looks like the last pictures is probably the fuse block x2 connector. Only solid purple wire on that connector is windshield wiper motor-high speed.

 

[Gtstorey]

Very first picture. X3 connector light green with black stripe is the hi beam feed after the pcb relay and fuse. Either they were switching something from that through a relay or the pcb relay died and they rigged something to replace it. Depends on what the wiring of the added relay does.

 

[DUNE]

Thank you for the detailed responses Gtstorey! Based off that I think ill just cut and label the mystery wires and trace them to their source once I have more of the harness accessible. Then if necessary I can re-connect them when I rework the harness

 

[ah.b.normal]

Its connected to a light blue/green wire running into the spark plug.

While looking at that one I also found another purple wire coming out of a different engine multi-plug, pictures are below. This one is the same deal where this spliced in purple wire runs into the cabin. Are there wiring diagrams for these plugs that I can reference?

The "Black Wiring Box" that connects under the fuse box is the "engine harness". Goblin doesn't have you modify this harness much, if at all. So Goblin doesn't talk about it much. Sadly many prior owners have cut into these wires leaving "mysterious wires" behind!(I call this stuff "NEW" For "Non Essential Wiring") That fat purple wire off the black fuse box wiring block is the starter wire. It is only live and feeding power to the starter solenoid(S terminal) when the key is held in the start position. Where does that (NEW)black wire go and is it just tapped into the purple wire or what? The other end of the fat purple wire(it only goes one place to do one thing, energize the starter) is a single connector that plugs into the Starter Solenoid at the starter(earlier models use a stud and nut with a ring connector at the end of that 8* purple wire). I believe your starter will have a 13mm nut on a (10mm)threaded post for the 0* or 1* gauge wire(tech term: really, really fat wire)battery feed(from) the battery and another similar gauge wire running to the the tall 10mm nut/stud on the front right corner of the fuse block(jump start post?) It may have a smaller 8*-10* gauge wire that feeds the 6mm threaded post on the back of the Alternator, but that may just be early models? When the battery is connected all of these wires are carrying +12volts battery power, AND lots of amps of power!, shorting(touching) them to ground(most every surface of this car) is BAD. It will cause sparks and even minor unintentional welding. ***DANGER*** In your engine compartment there is usually another black large gauge wire normally taped onto the huge wire running from the Jump post on the fuse box to the Starter Solenoid Battery post. Though this Jump post positive wire and this MYSTERY are similar wire size and color AND are taped together in their original installation, these large wires DO NOT in fact connect to each other! They are only taped together at the factory for assembly convenience. This other MYSTERY fat wire is the Engine to Chassis Ground. One end usually is connected to either a stud on the motor under the oil filter area or onto one of the bolts that hold the engine to the trans. The other end attaches to the body under the left headlight on most Cobalts. This fat wire is a GROUND ONLY! and should NEVER be connected to the copper threaded post on the Starter Solenoid!!! NEVER! Sorry if all of this sounds scolding but I have seen a couple of cases where Goblin builders have, in error, also connected that wire to the battery post on the starter! That sort of thing causes "a dead short" to the battery, which if you are lucky, causes the vehicle to not start, and if you are NOT LUCKY it can cause your GOBLIN to catch on FIRE!(Which nobody wants!) I know many folks will find this post pendantic and even repetitive but more than one builder has been tripped up by this one! I believe the wiring videos only mention this heavy ground wire once and not every builder has the benefit of having worked on GM cars since the mid 80's.(Historical FYI: On Chevys, the purple "start" wire has been the same since (at least) 1955)