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Brad
Brad, Jeep Dealership Tech
Category: Jeep
Satisfied Customers: 7511
Experience:  19 Yrs Chrysler/Dodge/Jeep. ASE Master (L-1) Certified
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I have a 2013 Rubicon Wrangler and I upgraded to a 300 amp

Customer Question

I have a 2013 Rubicon Wrangler and I upgraded to a 300 amp alternator and dual batteries. When I turn the ignition key to on the uconnect radio works and stays on but when I start the engine the radio stops working, goes off. Could it be a relay that is protecting the radio by shutting off, due to a surge from alternator. Not sure just guessing.
Please advice thanks. Frank
Submitted: 9 months ago.
Category: Jeep
Expert:  Brad replied 9 months ago.

Good afternoon and welcome to JustAnswer!!

My name is ***** ***** I have worked for a Chrysler-Dodge-Jeep dealership for 19 years and I will do my best to help.

I work part-time here on JustAnswer to help you and other repair their own vehicles, and I get credited by your ratings.. So before leaving the site make sure and leave me a rating. You can still reply to me as many times as needed, even after the rating.. I will need for you to be my hands and eyes since I'm not there, and to be honest with today's electronics a scantool may very well be needed to retrieve the codes or to monitor data to see what's going on...

Frank can I get the last 8 of your VIN number so I can grab a wiring diagram for your radio so we can see what's going on?

Talk soon,

Brad

Customer: replied 9 months ago.
DL612178. The uconnect radio worked fine until I installed the 300 amp alternator and dual batteries. Thanks
Expert:  Brad replied 9 months ago.

Thanks for the info!!

Ok I attached the radio wiring for your vehicle.. Can you start it up and check fuse M12 in the fuse box under the hood which supplies 12v to the radio.. Test it when the key it on and then running and let me know what you find.

Talk soon,

Brad

Customer: replied 9 months ago.
Hi Brad, with a voltmeter on DC 20 v, I removed the 30amp fuse and tested the fuse port with just the ignition positioned to on it tested at 1.8v but with the engine running it tested at a negative -3.6v. Frank
Expert:  Brad replied 9 months ago.
Leave the fuse in it and test at the top of the posts that stick thru the fuse.
Customer: replied 9 months ago.
I have over 12v either way, ignition on 12.6v and engine running 12. 5v.
Expert:  Brad replied 9 months ago.

Ok if you have 12v with it running and the radio will not work then you will need to pull the radio to make sure it's getting 12v and ground...

Customer: replied 9 months ago.
Ok, how could anything have changed regarding the radio, just by upgrading the alternator and installing batteries? The radio worked fine before I did these changes. Thanks Frank
Customer: replied 9 months ago.
Brad, wouldn't the radio already receive 12 volts since it's on when ignition key is on. If not receiving 12v or no ground wound the radio work when just in on position or does everything change when engine is running? Sorry just trying to understand.
Expert:  Brad replied 9 months ago.

I'm not sure but the next step will be to see if the radio is getting 12v from fuse M12 and if it has a ground.. If yes then you need a new radio.. If not then we need to start tracing wires back to the fuse..

Customer: replied 9 months ago.
Ouch!! Thanks
Expert:  Brad replied 9 months ago.

You are very welcome!!

If you need anymore assistance feel free to reply and don't forget the RATING before leaving the site!!

Have a great day,

Brad

Customer: replied 9 months ago.
Brad I checked the volts and with the engine running the fuse reads 17.8 volts. It seems their maybe a surge. Would a higher amp fuse help?
Customer: replied 9 months ago.
Not sure why it changed but I checked twice and it's at 18v.
Expert:  Brad replied 9 months ago.

What does your cluster amp meter say? 18v is too much and it seems the alternators are not being regulated down..

Customer: replied 9 months ago.
I checked various other fuses and they also register at 17.4 to 17.8v. I bought the alternator from ebay? Does the alternator need to be grounded or is it grounded by its attachment to the engine?
Expert:  Brad replied 9 months ago.

Yes the alternator is grounded when it's bolted to engine.. The PCM regulates the alternators so what is the voltage when you disconnect the small wires at the alternator? It would also help to now what % the PCM is commanding the alternator to charge at..

Customer: replied 9 months ago.
Hi Brad, when I disconnect the small wires on the alternator the radio is fine and stays on when the engine is running. What now? Good call man
Expert:  Brad replied 9 months ago.

Well that means the alternators are not being regulated properly. I would call the manufacturer and see about getting a replacement and tell them what it's charging at..

If you need anymore assistance feel free to reply and don't forget the RATING before leaving the site!!

Have a great day,

Brad

Expert:  Brad replied 9 months ago.

Well that means the alternators are not being regulated properly. I would call the manufacturer and see about getting a replacement and tell them what it's charging at..

If you need anymore assistance feel free to reply and don't forget the RATING before leaving the site!!

Have a great day,

Brad

Expert:  Brad replied 9 months ago.

I see you haven't rated yet which means I have not been credited for helping. Don't forget to honor your good faith deposit by rating my assistance..

Thank you and have a great day,

Brad