Printer Friendly Forum Posts - memory fuse shorting out

First off, I don't know that much about cars, so forgive me for my ignorance. I have a 1992 ford thunderbird, sony xplod head unit, 350w kenwood amp and 2 12" kenwood subs. I just finished installing this system today and the first time the subs kicked in, the head unit died. I finally found that it was the 5 amp memory fuse in the distribution box, and I'm told that fuse is for the computer. It didn't blow when it was mainly door speakers and no sub, but did when the subs kicked in. I made sure the extra wires from the harness were taped off. I used all factory wiring to the speakers. I don't think that this is a shorting problem because I made sure that all wires I spliced and connected are taped off.

Anyone know as to why it's blowing the memory fuse?

Where did you connect the amplifiers power wire?

Was it the fuse under the hood...?

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M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!

I connected the amp directly to the battery and then grounded to metal in the trunk. And yes, it was a fuse under the hood, and not in the fuse box under the dash.

I don't know why the head is pulling power from the memory fuse because there is a fuse specifically for the radio. Don't know if it would be this or not, but the key was turned to the accessory position and engine was not running.

There are 2 fuses that power your radio. The one labeled radio powers the switched 12 volt wire. The radio requires a constant voltage also. The fuse that feeds memory power to the radio usually feeds the cigarette lighter or the horn. Do either of those quit working when the radio quits. Usually it is a 15 or 20 amp fuse in that slot. Look in the owners manual and see if you can find out if the fuse is supposed to be larger than 5 amps. If you can find no info about the fuse size, DO NOT PUT A LARGER FUSE IN THE SLOT. If it calls for a 15 amp fuse in that slot, yut one.You may need to run a 12 Ga. wire to the battery, fuse it at 10 amps at the battery. Connect the Yellow wire of the deck to the newly ran wire.

I think Mr I is spot on with the adding a 12 volt lead....Although my old install buddy would just upgrade the fuse on those cars... I dont know the repurcussions of this(other then the obvious)...But the cars never came back...Maybe because they just burned up where they sat...So...Running a new lead would be the safest bet...!

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M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!

It's been years since I've messed with one of those, but isn't that only a 5A fuse?

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Kevin Pierson

If it is supposed to be a 5 amp fuse, you really need to run the wire from the battery as I suggested earlier.

I looked through the manual and it showed the memory fuse to be 5 amp, but it did not say anything as to it powering the radio. When the fuse is blown, the horn and cigarette lighter still work , but the radio has no power even with the car running. I have replaced it 4 times now, most of the time it blows, but a couple times it ran fine with the volume maxed.

The harness I bought had a ground wire coming from it, so I just connected the radio ground to that. Should I ground it to the car somewhere?

It was made for factory radio...Just run a new 12volt lead as Mr.I suggested...Fuse it and your good...! This is very common on these cars...My very,very,very first install was this very car...And had this very same problem...Again my senior tech just upgraded the fuse...And insisted that was more then sufficient...But lets just be safe and run a new fused lead...2 insulated female spades and a blade fuse will do the trick...!

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M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!

ok, what do I do about power control (remote start ?) because wouldn't wiring it directly to the battery drain it?

Not sure of the question...All radios have a constant 12volt source...This is what holds memory...So unless there is a problem with the radio shutting off...It will work as it always did...Minus the fuse blowing...! The wire it is attached to now is 12 volts even when key is off...otherwise everytime you start the car you would have to reset the bass/treble settings as well as all the presets...etc...!

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M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!

It is actually the red wire on the stereo that powers up with the key and tells the radio to turn on...Yellow wire is constant...Red wire is Accessory...! So connect the yellow(as mr. i stated) to the lead that you run to the battery...Make sure you fuse it...Otherwise that wire will burn from battery to stereo if ever there is a problem...About 6 inches'ish from where you make the connectiopn at the battery...Cut the wire in two...Crimp on an insulated female spade on each side of the cut wire...Push the blade/automotive fuse in each slot...Good to go....! Just to be safe...Make the fuse holder and put it in-line before making connection...! It is very important that the fuse is a close as possible to the connection at the battery...Dont put the fuse on the inside of the car...But ONLY a couple inches from the battery!!!!

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M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!

From the radio, there is a 12v switched and a 12v constant lead. I just attach the new wire to the constant supply, and not the switched?

And let me get this straight, even if the car is running and memory fuse is blown, the radio still won't turn on...even though it has 12v coming from the switched supply?

Correct...It needs both Accessory and constant to turn on...Just having one will not turn the radio ON...The switched should be fine...You can verify this with a meter...!

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M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!

If you were to put both the yellow and red leads to this wire(the one you are going to run from the battery)...Then YES...the battery would drain because the radio would never shut-off...!

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M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!

But it sounds like the constant wire(yellow) is the only one your having an issue with...Right...?

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M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!

I think thats the only one I'm having problems with. I will verify with a meter, run the new wire and post back if that doesn't fix it.

Thanks everyone!

jogie] wrote:

strong>ok, what do I do about power control (remote start ?) because wouldn't wiring it directly to the battery drain it?

I still didnt follow this question...Or does it not matter now...?

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M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!

I see now. I've realized that the 12v switched is what turns the radio on.

change the remote wire from factory fuse. to a different one..............

Wired the radio to the battery using a 16 gauge wire and 10 amp inline fuse. Also wired the radio to a new ground point. Works perfect and no more blown fuses!

Thanks everyone!

mamartinez1213 wrote:

change the remote wire from factory fuse. to a different one..............

What is the quote trying to say...I didnt follow that one...? Glad you got it...Did you fuse by the battery...?

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M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!

Seems that guy is drinking on the job isn't he tommy! I can't figure out what he's trying to say either!

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COMMIT YOUR WAY TO JEHOVAH AND HE WILL ACT IN YOUR BEHALF. PSALMS 37:5

[QUOTE=t&t tech]Seems that guy is drinking on the job isn't he tommy! I can't figure out what he's trying to say either![/QUOTE

Sippin on grandpa's cough syrup...ey...?

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M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!