Why does Fuse #23 blow as soon as I install it?

[Ozz]

A couple of weeks ago fuse #23 under the dash blew. I knew it because my dash clock, door lock switches and interior lights didn’t work. I replaced it and was fine for two weeks.
Today when I got to work I noticed that the clock was out again. I reached under the dash and removed #23 which was blown again. Since I still had a few new fuses in the cup holder, I popped another one in. It blew instantly, as did a third one…
I had the doors closed so I don’t think it was the interior lights, or door locks. What could be causing this?
The owners manual says this fuse controls the following: EATC Module, Instrument Cluster, Clock, LCM, Interior Lamps, Door Lock Switches.
What is the EATC (something 'temp control' I assume) and LCM?
<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com /><o:p></o:p></P><P><FONT face=Modifications I have made that may affect this circuit:
Changed speakers in the doors about 5 months ago. Changed the oil and volt gauges to new AutoLite pieces – used stock wiring.
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I will check the harness in the door and try to install the fuse with the switches unhooked but what else can I try at home to diagnose this problem? I really don’t want to pay a dealer to fix this.
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Thanks!!

[RoyLPita]

Are you still in base warranty?? If so, take it in. If not, try disconecting the clock and other items that apply.

[grampaws]

The interior lights have a wires going under the drivers kick
plate. Often they have a plug at the bottom of the B-pillar that
with a little moisture or pinched under the plastic panel shorts out..
The int light wires would be the place i would start...

[Ozz]

...I also have my radar detector hard wired into the connector in the overhead console... hmmm.. I will look there too.

Any other ideas?

Thanks!

[STLR FN]

What is the EATC (something 'temp control' I assume) and LCM?Too answer this question EATC is the Electronic Automatic Temperature Control(your heat and A/C) and LCM is the Lighting Control Module-controls your theater(dimming) lighting when you open and shut the doors.
As far as what's causing the fuse to blow out?? dunno but radar detector and unplugging things like Roy said would be a good place to start.

[Ozz]

LCM... hmmm... I have different bulbs in the interior than stock. They use slightly more wattage. Combined, all 7 interior bulbs use 10 more watts than the stock bulbs.... negligible I think.
The door was closed and the lights were off when the fuse blew today so I don't think it's the bulb draw but the draw may have messed up the LCM...
Would an extra 10 watts fry the module???
Where is the LCM by the way? I will unplug it and try the fuse again.

What about the EATC - where is it located?

THANKS!

[STLR FN]

LCM... hmmm... I have different bulbs in the interior than stock. They use slightly more wattage. Combined, all 7 interior bulbs use 10 more watts than the stock bulbs.... negligible I think.
The door was closed and the lights were off when the fuse blew today so I don't think it's the bulb draw but the draw may have messed up the LCM...
Would an extra 10 watts fry the module???
Where is the LCM by the way? I will unplug it and try the fuse again.

What about the EATC - where is it located?

THANKS!The EATC is your heating and a/c controls right above your gauge pods and below your radio. As posted by shakes 26 in this thread:
http://www.mercurymarauder.net/forums/showthread.php?t=25301&highlight=LCM




Its pretty much right above the accelerator pedal, but closer to the center console than the firewall.

You'll need to pull the access cover, a few plastic trees, thats all that hold that.
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[Ozz]

So EATC means the actual visible control head? I was thinking there was a module or something else behind the visible part.
I think I will unplug everything else before tackling the EATC. Lighting first!

Thanks for the info!!!

[STLR FN]

So EATC means the actual visible control head? I was thinking there was a module or something else behind the visible part.
I think I will unplug everything else before tackling the EATC. Lighting first!

Thanks for the info!!!Yeap and no problem. I would seriously doubt it's the EATC.

[carfixer]

Fuse F2-23 covers a lot of stuff.

One of the most common things we see are the visors shorting out at the pivot. Try moving the visors to a different position and see if a fuse will go in without blowing. If the fuse doesn't blow right away, try moving the visor and see if the fuse blows.

Other things it protects:
All interior lamps, including the trunk, hood and glovebox.
Power to the overhead console.
Door ajar switches.
Clock.
Instrument Cluster.
A/C head.

[fastblackmerc]

1. Disconnect all devices that are powered by that fuse.
2. Hook up one device at a time until you find the one that blows the fuse.
3. Replace / repair that device.

[Marauderman]

1. Disconnect all devices that are powered by that fuse.
2. Hook up one device at a time until you find the one that blows the fuse.
3. Replace / repair that device.
...see.....now that is how to find it the simple way.............and he's in our Carolina Marauder group......( a kinda solve-it-all type guy) ......and ....no .......no one can have him...I'd try it his way ---you'll be suprised.....he's had more years than he'll admit on this stuff....a jack of all....naw---we're not going there---carry on....:lol:

[Master]

FYI: Regarding the question "would 10 more watts be enough to blow a fuse":
W=VxA.
W is Watts
V is volts
A is Amps
We have a 12 volt system, so the 10 watts / 12 Volts = 0.83A, or just shy of an extra amp. Now add on the radar detector - How many amps? I don't know. Add any extra load from the new gauges (if any).
I'm not saying that an extra couple of amps will blow the fuse - they are usually sized about 30% above design load. I'm just adding this so you, and anyone else who might make electrical changes is aware of how simple it is to see if you have exceeded the spec for a fuse. Keep in mind that exceeding spec doesn't mean you should be putting in a larger fuse. The wiring, too, is sized for this load. Unless you feel like re-wiring your car, try to keep the added load to with 90% of the fuse as a maximum. Any more and you run the ristk of popping fuses on a regular basis.
Again, I don't think this is your problem based upon the information you provide. I concur completely with those members who have suggested a methodical approach to troubleshooting.
Best of luck with this issue!

[Ozz]

carfixer wins the prize.

As I was driving home last night I realized that the last time the fuse blew was on a sunny morning like yesterday. To block the sun I moved the visor to the side to get to the secondary visor (the regular one hangs down too far and blocks my view of the road). I then remembered that I had the visor out about a month ago to install some sound absorbing insulation above the headliner to eliminate a 'scratchy' noise that was driving me nuts... It also occured to me that nonfunctioning visor lamps/pinched wire/difficult visor install are common warranty/build issues.
I checked and sure enough, the wire was pinched under the visor attachment. I taped it up and reinstalled the visor and all is well.

I was planning a scientific approach much like fastblackmerc recommended but thought that there was probably some 'insider information' on this site about 'typical' problems that occur with this particular circuit. carfixer supplied this info and it turned out to be spot on. THANKS EVERYONE!!!

PS: The radar detector was jumpered to the circuit that powers the compass so it was not on the problem circuit.

[Dragcity]

Yet another satisfied customer....

[fastblackmerc]

Glad you found it. Electrical shorts can be a real pain-in-the a$$ to find.

[ckadiddle]

Carfixer is da bomb.

[David Morton]

Carfixer is da bomb.

What he said. Knew it the minute I met the guy.

[GrazniM]

This is an old thread, but in the past week or so I encountered the exact same issue (and blew a pack of fuses unsuccessfully trying to figure it out). It turns out that in my case as well carfixers note re. the visor was absolutely correct - if I moved the passenger visor ...POP.

Thanks to carfixer :2thumbs: , and just some additional comment for FUSE #23 victims that may search MMNet threads in the future.



Fuse F2-23 covers a lot of stuff.

One of the most common things we see are the visors shorting out at the pivot. Try moving the visors to a different position and see if a fuse will go in without blowing. If the fuse doesn't blow right away, try moving the visor and see if the fuse blows.

Other things it protects:
All interior lamps, including the trunk, hood and glovebox.
Power to the overhead console.
Door ajar switches.
Clock.
Instrument Cluster.
A/C head.

[Ozz]

It's funny this thread was resurected. I worked for the company that made the visors when I started this thread. I bought my car from the Director of Engineering at the same company. I found out later from one of her engineers that my car was used to try out CV/GM/MM visor changes/fixes before I bought it from her. No wonder the visor wire got pinched... I must admit, the visor wire was fine until I took it out and reinstalled it. :rolleyes:

[GrazniM]

I've been using the visors heavily - I tip them down to help hold a reflective sun shield in-place when I park the car out in the sun (often); I guess I wore-out the passenger side....:o




It's funny this thread was resurected. I worked for the company that made the visors when I started this thread. I bought my car from the Director of Engineering at the same company. I found out later from one of her engineers that my car was used to try out CV/GM/MM visor changes/fixes before I bought it from her. No wonder the visor wire got pinched... I must admit, the visor wire was fine until I took it out and reinstalled it. :rolleyes: