My ACC fuse used to blow every once in a while, mostly while using the cigarette lighter to charge stuff when the car wasnt running. Now it doesnt blow anymore, the fuse is still good. But none of the accessories work.

So I busted out the voltmeter, and of course none of the accessories have 12v. Not even the cigarette lighter which is supposed to have a constant 12v. (Yes I took off the bezel). Tried the dome light, door lock switches none of them have 12v.

So whats my next step? I have the wiring diagram but that doesnt really help me locate where the stuff actually is, like where the fusible link is, and where the is split into all the accessories.

 

I would check for a bad connection or burnt wire on the back of fuse box where the acc fuse is located. Also check that you have 12 volts on both sides of the fuse

 

I have 12 volts on both sides of the fuse.. Didnt see anything out of the ordinary behind the fuse box.. I do have a black wire and a black/white wire that are stuck together and just dangling under the dash, not connected to anything.

I already checked the cigarette lighter, its not getting 12v behind the dash. My dome light was kind of intermittant.. Would a short there cause the whole circuit to not have 12v anymore?

 

 

Well whats the first accessory? This diagram seems to indicate everything is in parallel. http://www.austinthirdgen.org/mkport...s_ACC_fuse.jpg

The wires just went into a wire loom up into the dash, so I guess I have to dig deeper. It was kind of hard to get a look behind the fuse box, even after dropping it out of the clips

 

Is there any way to take out the fuse box instead of just flipping it down? Its way too hard for me to see whats going on back there

 

Pull the dash pad off.
Only a few screws hold it in place, and you can get at them all with a 75-cent screwdriver.

When the pad is out of the way you should be able to easily inspect the yellow wire that feeds the accessories.

Some doofus probably had at the yellow wirer with his pocket knife to tap power while he was installing a Remco mirror-ball or some such garbage in a sordid chapter of your third-gen's history.

 

Some PO's just have no shame.

 

This probably wont help you but since nobody has answered you in awhile I thought I would try. On my 92 rs the same fuse would blow for me once in awhile, operates the cig, the horn, and the dome light. After replacing 3 times in the same month I finally found that my cig lighter was rusted just enuff to be the culprit. Unplugged the cig lighter (still have not replaced) and have not had a problem with that fuse again.

4 some reason site didn't show last 3 or 4 replys - my bad.

 

Did you do any changes to the car prior to when the fuse would blow out? And check your battery cables, and the negative cable should have a ground to the chassis/frame of the car.

 

I did install a deck and sub around when it start happening. There was another aftermarket deck in there before, so it already had a wiring harness. It was just plug and play. There was also another sub in there before, so that was also plug and play. I did replace the power wire to the sub with a larger gauge, and I didn't replace the ground wire to match the larger gauge. I just double checked the wiring harness connections. They all seem solid, though whoever did it left some bare wire poking out of the sides of the insulation. They did wrap it in tape at least.

I'm gonna fix it tomorrow, but if the yellow accesory wire wasn't going through to the head unit, it wouldn't work right? So that's weird, it seems the head unit is getting the accessory power from the yellow wire, but nowhere else is. I will dig deeper behind the head unit and follow the yellow wire to the fuse box.

Could it be because I'm using a 200A fuse near my battery for the power cable to my amp? I know it's overkill, but a lot of people have told me it shouldn't matter.

I tried disconnecting the cigarette lighter and that didn't help.

The battery ground looks good. The metal is very bare, and it's a bolt close to the battery so the ground cable is short.

 

I still can't find the problem.. I've had my dash apart a lot since I'm putting in another amp. I redid a few small wiring mistakes in various places, but still can't find why the whole circuit wouldn't be working.

It's weird, my aftermarket deck works fine, and the light in my trunk works fine too. (when I open my trunk, the light near the trunk motor turns out)

 

Hey,

Not trying to hijack your thread - but I have a similar problem. Difference is that my interior dome light DOES still work. But something is fried on my end as well, and I didn't see anything obvious behind the fuse box. Guess I will pull my dash off as well. Here is my post:

The wires running to one of my manual cooling fans was routed under the battery and 2 of them were frayed, causing the AC/Heater fuse to blow. I replaced the fuse with a higher rated one and then something fried - and that fuse melted a bit but never burnt out...But the digital dash went out, so did the information center, the heat/AC has no power to it, nor do the power door locks, power windows, or power mirrors.

Other than that the car runs great! But it's a sweat box, and un-drivable without any functioning gauges.

Any ideas what could have fried? Is there a relay or something that could control all these accessories?