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Battery light stays

Tiny
JACKWILSON7272
  • MEMBER
  • 2014 JEEP COMPASS
  • 4 CYL
  • 80,000 MILES
While installing a new battery, I crossed connected the battery cables and sparks flew. Made the correction, car started but battery light is now on. Advance Auto tested the battery and it was okay but down just a little. Told me to keep driving and the light should go off. Car gave out and had to call my wife to come get me. Took battery out, swapped it for new one, light still on. Was told alternator was bad. Now have new battery and alternator, but light still on. Now between Googling and YouTube, I am lost. The worse news I got was that I needed to take it to the dealer and have them check the "master fuse", whatever that is. He claims it is very expensive and very hard to do. Any idea's. On YouTube someone change the relays around and it worked but not on my car. Another site said it is a fried wire going to the starter. Mine are okay, so the friend who checked it said. Any ideas? I am not a car person and cannot give a dealership a couple of thousand dollars to "check it out" Any ideas that can save me? I am praying it is something simple. Thanks, Jack
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Sunday, October 8th, 2017 AT 12:02 PM

7 Replies

Tiny
STEVE W.
  • MECHANIC
  • 13,018 POSTS
Reversing the polarity on a battery on modern vehicles can easily destroy expensive parts.

The battery light being on means the charging system is not working. That is why it died after you let AutoZone check it.

The first step will be to test all of the fuses. To do that you want a simple test light.
https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester
Hopefully it is a simple fuse failure but it usually isn't that simple on newer vehicles.

To provide better information please provide the engine size and if it is two or four wheel drive. Jeep used a 2.0 L and a 2.4 L in the Compass and the wiring is different.

If it is not a fuse you are probably looking at replacement of either the TIPM (smart fuse box which has a lot of electronics in it) or if it hit the regulator itself the PCM may need to be replaced as well. Neither of those are a DIY item as they both need to be programmed to match your vehicle.

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Sunday, October 8th, 2017 AT 1:52 PM
Tiny
JACKWILSON7272
  • MEMBER
  • 5 POSTS
Thanks. I think your probably right. Took it to a station a friend of mine has and he said he thought it was the Power Train Module which I guess is the same as the PCM. He never mentioned the TIPM. I checked all the fuses in the top fuse box and only found 1 that was blown, a 20 amp interior lock and light fuses, and replaced that one. He suggested I take it to a "auto electric" place to have it tested. ( $103.00 with a 2 day wait) It's truly a nightmare as I now have 2 new batteries, had someone install two alternators because I was told they where bad and now the guy who has the station said, "heck, it might not have been the alternator at all" REALLY! Now, so far, I've spent over $300.00, and the car is no better off then the day it happened. And it looks like it's still a huge uphill battle.
I'm not sure if I have a 2.0L or a 2.4L. I will check on that when I get it from the station tomorrow. Maybe I'll get real lucky and the battery will have enough life to make it home. Thanks for your help. Very much appreciated. Not sure what my next step will be but we appreciate ya.
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Thursday, October 19th, 2017 AT 4:08 PM
Tiny
STEVE W.
  • MECHANIC
  • 13,018 POSTS
The TIPM in them is REAL easy to fry. It has electronics inside it that control a lot of stuff as well as passing power around. BUT it's not a cheap part. Sounds like you need to find a good diagnostics shop, that alone can be a nightmare.
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Thursday, October 19th, 2017 AT 7:31 PM
Tiny
JACKWILSON7272
  • MEMBER
  • 5 POSTS
Thanks for getting back Steve. I know you said these are not DIY parts but I was checking some things last night and came across a PCM website and it said "plug and play" no programming needed. Is this a option or no. Thanks
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Friday, October 20th, 2017 AT 12:59 PM
Tiny
STEVE W.
  • MECHANIC
  • 13,018 POSTS
I would be REAL careful. The PCM has to have the correct VIN and options programmed to match your vehicle. They may offer that as part of the service but I prefer doing it on the vehicle. That way you also get all the latest updates and are less likely to have a brick.
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Saturday, October 21st, 2017 AT 12:19 AM
Tiny
JACKWILSON7272
  • MEMBER
  • 5 POSTS
Which one normally goes 1st, the TIPM or the PCM in a situation like this? I know it's probably hard to call but just "in general" is there one that may get sick before the other. (Still messing around with this thing) Thanks
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Saturday, October 28th, 2017 AT 9:31 AM
Tiny
STEVE W.
  • MECHANIC
  • 13,018 POSTS
50/50, it depends on what was on or came on at the time the battery was connected.
The light itself is simple. One side goes to the regulator and connects to it's feed from the alternator. The other side goes to the alternator and reads what voltage it is putting out. The light will come on with the bulb check and go out when the alternator starts charging and the voltages match on both sides.

That would point at the problem being in the alternator or the PCM. BUT the PCM gets the voltage it compares the alternator voltage to through the TIPM.

What I would probably do is find the wires in the diagram, then measure them for voltage. The one that is dead with the engine running is the one to trace.
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Saturday, October 28th, 2017 AT 5:22 PM

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