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C. Walker, Jr.
C. Walker, Jr., Auto Mechanic
Category: Subaru
Satisfied Customers: 711
Experience:  Shop training and experience.
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I was swapping the battery while I had the ignition on but

Customer Question

I was swapping the battery while I had the ignition on but car off and all the power inside shut off.
I can't even start the car I hear the open door sound but I try to over ride the alarm but nothing happens when I push the button.
Submitted: 1 year ago.
Category: Subaru
Customer: replied 1 year ago.
I forgot to mention while the key was on the on position but car off I kinda messed up and put the positive in the negative and the negative in the positive. After that nothing worked inside no power all other than the alarm flashing lights and no start. No crank. Nada
Expert:  C. Walker, Jr. replied 1 year ago.

Good evening, there are three fuses that are now going to be blown. 2 30amp and 1 80 amp fuses. These are under the hood in the fuse block.

Customer: replied 1 year ago.
Weird I checked those and there good.
Customer: replied 1 year ago.
Could you send me a pic of a blown fuse?
Customer: replied 1 year ago.
The only one I saw blown was inside the dash it was a 20amp
Expert:  C. Walker, Jr. replied 1 year ago.

That is impossible. I literally tested a fuse yesterday and it also said it was great making me spend 4 hours trying to diagnose a problem that was just the fuse the entire time. I would just replace the fuses to be sure they are good. But those 3 are the protection fuses coming right from the battery.

Customer: replied 1 year ago.
Okay. I could find those at any auto parts?
Expert:  C. Walker, Jr. replied 1 year ago.

Yes you can get them from any parts store. You can as a temp way to verify it is the fuse just run a piece of wire in between there just to see if it is those 3 fuses even know they look mint it sometimes is very deceiving even a skilled mechanic as myself missed one yesterday as my multi-meter told me it was good.

Expert:  C. Walker, Jr. replied 1 year ago.

Also another big thing you have to make sure of is the battery is not reversed. If you put a volt meter accross the positive and negative it should say 12v if it shows - 12 volts than you have to discharge the battery. Make sure as it will fry the system if you try putting a wire in the fuse holder and the battery is discharged. If those fuses are good that is a BIG issue because the negative current got passed them into everything if you shorted out the ECM engine control module that will be a headache. That is what those are there for is if the battery is shorted to ground or spike in voltage they should 100% be blown!

Customer: replied 1 year ago.
Okay the battery I reversed the cables with was fully charged. For a fact because I used that battery to start my car and then I would let the car run while disconnecting the batter to put in the battery that was discharged. I'll check those tomorrow morning when I was putting my focused more on the smaller fuses than those that you are talking.
It should be two red 30am
And one that is being held by 2 nuts right?
Expert:  C. Walker, Jr. replied 1 year ago.

Yes, slots 1(nuts) 5 and 6 the 30s get back to me asap I will help you until we resolve the problem. But I am pretty sure that baby is popped been doing this a long time and its pretty common but very good for you as it saves you thousands in computers.

Customer: replied 1 year ago.
Okay.
I'll even send you pics of the fuses tomorrow morning.
Will you be available tomorrow morning around 9am?
Expert:  C. Walker, Jr. replied 1 year ago.

I will be here.

Customer: replied 1 year ago.
the 2 30amp where in good shape but the 80amp was shot
Expert:  C. Walker, Jr. replied 1 year ago.

It hits the 80 first so that is normal. Sometimes it will kill all 3 but you are good. Everything working now and your back up and running?

Customer: replied 1 year ago.
Just got the fuses
Just replacing all 3 just in case like you said to make sure everything is running
Expert:  C. Walker, Jr. replied 1 year ago.

That is the only way to be sure. Keep the 30s as spares you never know one day you will need them.