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Something could now be reverse-polarized. If anything like a dynamo with windings was connected backwards, it could now be opposite due to being connected backwards. A fuse isn't going to know the difference in "polarity" in this case, so one isn't going to blow if you connected things backwards. You're looking for something like a diode or something that only allows electricity to run one direction. Any DC-motor would have run in reverse when connected this way. You say it was connected and drove normally for 3 days connected backwards with nothing apparently inoperative?

I'm surprised the computer couldn't tell the difference between +12v and -12v and allowed anything to operate in the first place. connecting jumper cables backwards could cause very bad things to happen, but you seem to be saying you just connected a single 12v battery backwards. RIght?
 

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What I would do: I own a multimeter and an inductive clamp on current probe. Also have a variable voltage current limited power supply. I might be tempted to slowly turn up the voltage and watch where the current is going. Just to get a rough idea. or remove a fuse, use clip leads to get access to the current, flowing through the fuse and measure the current that way. The hardest thing for me, would be to try to avoid guessing, and acting on a guess. I always guess wrong and waste time. Instead, figure out someway to find the smoking gun. I’m sure this is already stuff you’ve thought of.
 

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Discussion Starter · #23 ·
It didn’t run for a few days reverse. It was connected that way for a minute before I realized my mistake. Got a new battery after that and it ran a few days before going dead.
 

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Ok, so you're saying you temporarily (for a minute) connected the battery in backwards. You realized your mistake and swapped them around. It drove fine for 3 days and now the battery is dead? Is that right?

An alternator has diodes in it as it produces alternating current which must them be converted to DC voltage for use in the car. It could be that these diodes have failed or that the alternator itself is now reverse-polarized (I don't know how the windings between a generator an alternator differ), so you basically have no charging system. A new battery would work, but would also go flat in a few days. You can check that with a meter, of course, verifying the output voltage from the alternator. Back in the day, people would actually take apart alternators/generators to swap out the diodes, brushes, and the bearings to re-new their alternators.
 

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Ok, so you're saying you temporarily (for a minute) connected the battery in backwards. You realized your mistake and swapped them around. It drove fine for 3 days and now the battery is dead? Is that right?

An alternator has diodes in it as it produces alternating current which must then be converted to DC voltage for use in the car. It could be that these diodes have failed or that the alternator itself is now reverse-polarized (I don't know how the windings between a generator and alternator differ), so you basically have no charging system. A new battery would work, but would also go flat in a few days. You can check that with a meter, of course, verifying the output voltage from the alternator. Back in the day, people would actually take apart alternators/generators to swap out the diodes, brushes, and the bearings to re-new their alternators.
I'm one of those people who used to take alternators and generators and voltage regulators apart to fix them.

I can assure you - due to the basic differences in how an alternator and a generator work (one has permanent field magnets, one doesn't, one has a segmented commutator the other doesn't) that an alternator will never put out reverse polarity.

It may however put out a voltage that measures OK with a voltmeter, but has no current behind it (limiting charging) or DC voltage with a high percentage of AC ripple on it (caused by shorted diodes - the clue for that is the diodes often "sing" - make a singing sort of noise 'zzzzzzzzzz' when shorted.) And sometimes both happen at the same time.

The battery in the car works like a great big capacitor and helps to dampen the AC ripple. It's enough with a healthy battery/alternator that the ripple isn't an issue. If the diodes are shorted, or the battery is weak - enough ripple can get through to disable some devices and perhaps destroy other devices.

Part of what causes electronic device failures after a battery reverse connection is the sparking that occurs as you connect the battery and then in a panic disconnect it. That sparking causes high-voltage spikes to travel through the entire electrical system of the car, causing damage that may not immediately show up (eventual solid-state-device failures - used by "T" failures of the device substrate.) They might show up hours, days or even weeks later.

That's also the reason that in general - jump-starting of any modern car isn't recommended or suggested by the vehicle manufacturers. They typically call for charging the battery, sometimes with the positive lead from the electrical system disconnected. It's not JUST the reverse connection that causes the issue (as I mentioned - that's pretty simple to protect against) - but it's the high-voltage spikes. That's harder to protect against (think surge-protectors, typically once they see a surge the protection is now no longer active - the device sacrifices itself to protect the other devices that are connected to it.)

I believe what he said was - he reversed the battery connection, disconnected it, reconnected it correctly and the car ran. Now after 3 days it no longer runs despite installing a new battery. I think he also made mention of the fans running as soon as he hooks up a battery to the car.

The hardest thing for me, would be to try to avoid guessing, and acting on a guess. I always guess wrong and waste time. Instead, figure out someway to find the smoking gun. I’m sure this is already stuff you’ve thought of.
David made a very astutue comment here.. guessing gets expensive since the last part you change will be the defective one - but you might change a LOT of other parts getting there. Hence my suggestion (strong suggestion) of getting it hooked up to a diagnostics tool.
Or take it to a dealer who I'm certain is no stranger to this issue.
 

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Discussion Starter · #26 ·
The battery is fine. The fans immediately start when hooked up, the car recognizes the key and unlocks the steering wheel, the doors lock/unlock and the trunks open but that’s all that works. Battery shows 12.5v
 

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Discussion Starter · #27 ·
Update. I haven’t got the scan tool yet but I did find the relay in the rear trunk for the engine compartment fan, pulled it and same noise. I pulled everything back apart and dc the starter. Turns out it was the starter constantly spinning while battery connected. Once I dc’d it everything else in the car works again. I’m going to have the new starter tested tomorrow but is there a starter relay/ switch to lock for as well and location would be appreciated.
 

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Update. I haven’t got the scan tool yet but I did find the relay in the rear trunk for the engine compartment fan, pulled it and same noise. I pulled everything back apart and dc the starter. Turns out it was the starter constantly spinning while battery connected. Once I dc’d it everything else in the car works again. I’m going to have the new starter tested tomorrow but is there a starter relay/ switch to lock for as well and location would be appreciated.
I think if you're intent on solving this yourself - it's time to man up for an AllDataDIY subscription. I can snip things from my subscription, but since your car (from memory) is a 987.1 and mine is a 987.2 - things may not be the same. Circuits might not be the same. Somewhere I posted a message about how to get a discount subscription to ADD that makes it reasonable for the average DIY'er to subscribe to.

Here is what my subscription shows for a 987.2 starter circuit:

Rectangle Slope Font Parallel Diagram


Before replacing anything - I'd suggest disconnecting terminal 50 on the starter. This is the power feed to the solenoid on the starter. That solenoid does two things - it connects high current battery voltage to the starter windings so the starter turns and it pull the starter pinion out to engage with the teeth on the flywheel so the turning starter will turn the engine over.

Since the starter motor is running, it's almost certain the starter solenoid is passing current to the starter motor windings. The question might be - if that's true - why isn't the pinion being moved out to engage the flywheel? This might point to a defective starter.

If you disconnect terminal 50 (yellow wire) - that should de-energise the starter solenoid. If the starter keeps running at that point - then there is a defect in the starter. If it stops when T-50 is disconnected, then you need to look upstream for the issue, perhaps at the stater relay they show in the diagram.

Good luck, let us know what you find out.
 

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Here's what the 987.1 schematic shows
I did it as an image of the PDF - which makes it possible for people to view it without having to download it to their computer (some people just won't do that..)

Rectangle Slope Schematic Font Parallel


The diagram is basically identical for the starter part except for the PAS and MFI-DI (whatever those are..) but the important part is terminal 50 on the starter. This will be the SMALL wire going to the starter, in the case of a 987.1 it appears to be red/gray instead of yellow as on the .2 car. Disconnect it - hook up the battery - if the starter turns the solenoid on the starter is cooked and you need a new starter.
 

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Discussion Starter · #31 ·
last night I disconnected the small single wire before anything else and it still spun when the battery was connected. I had the starter tested today at autozone and a starter/ alternator shop and both said it was good but I suspected it would test good and still be the problem.
 

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Do this at your OWN RISK.. I'm not telling you to do something, I'm telling you what I would do in this situation.

Assuming you have the starter out.. and you have a 12V battery and some jumper cables..

Find a way to secure the starter to a bench of some sort (a large vice would work, or even wood clamps)
Carefully connect the black jumper cable to the negative terminal on a battery and to the housing of the starter (normally there are lugs with holes that are used to bolt the starter to the block.. attaching the negative cable to it should work fine.)

Then take the positive terminal and connect it to the big terminal on the starter (terminal #30) and then to the positive side of the battery.

Does the starter immediately start turning? If so - the solenoid is bad.

If not (it doesn't turn) - proceed to the next step:

Starter connected as above - take a small wire and run it from terminal 30 on the starter to Terminal 50 (the big terminal) do you hear a "clack" noise and does the pinion on the starter output move out from the starter body? And does the starter start turning? If that happens the starter is probably OK.

DO take off any rings/watches/metal jewelry before starting this test (DAMHIK - IJD) DO be very careful not to cross the cables from the battery or let the ends of the jumper cables touch each other.

let us know the result of the test above.
 
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I did it as an image of the PDF - which makes it possible for people to view it without having to download it to their computer (some people just won't do that..)

View attachment 285794

The diagram is basically identical for the starter part except for the PAS and MFI-DI (whatever those are..) but the important part is terminal 50 on the starter. This will be the SMALL wire going to the starter, in the case of a 987.1 it appears to be red/gray instead of yellow as on the .2 car. Disconnect it - hook up the battery - if the starter turns the solenoid on the starter is cooked and you need a new starter.
Thanks Don makes sense
 

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Discussion Starter · #34 ·
When I had it at autozone today I watched them test it and it did as you said in the second test with the pinion coming out but when it was in the car and battery hooked up it was just constant spinning with no contact to the flywheel. It’s still out and I’ll probably do this tomorrow
 

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Discussion Starter · #37 ·
Can’t forget to mention how I would love to slap the **** out of everyone at the parts stores with the “joys of owning an import” comments. Bitch I’ve owned my car 5 years basically problem free this happened because of me. All of my vehicles are imports for that matter.
 

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Glad to see you figured it out. I assume when you connected positive to the big gold bolt nothing happened. Then you jumpered from the big gold bolt (12V+) to the small terminal (T-50) the starter spun and the pinion extended?
 
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