Fused Blowing

[Innov8]

I had some body work done on the ds rear quarter after a meeting with the gaurd rail at LRP (2 years ago!). Since that time, the drivers side parking lights have been popping fuses repeatly. I only really driver during daylight hours so it isn't that big of a deal but I just want it fixed... I've gone through 2 boxes of fuses trying may different things. For awhile this evening it seemed to be fixed, as soon as I finished re-assembly, and close the door...the fuse blows again.

I have:

Cleaned the ground and checked all the wires into the housing.
Cleaned the ground and checked all the wires behind the fixute and into the engine compartment (I didn't look behind the CD box but the body damage wasn't really that bad or deep so I doubt that there is a short back there...)
Try unplugging all of the bulbs
The only time it seemed to work was when I unplugged the bulbs from both tail light fixtures and plugged them back in one by one... but this doesn't make any sense becuase the driver side and passenger side are on different fuses and when the fuse blows, it is only the drivers side that goes.

I'm stuck. What do I try next...following the wires back all the way to the fuse box? Is there something I am only looking? Could it just be coinsidence that this is happening after the trip to the body shop?

Pls help with your always sound advice. Does anyone know of a good automotive electrician in WS CT? Thank you!

[JMAN718]

I had a same problem , just try disconnecting the wires from the rear deck lid. There is a light outlet that seem to get rusted in time. I hope this will solve your problem.

Jman718

[Innov8]

Thanks Jman.
Unfortunately, there is no light on the aftermarket engine deck lid. BUT maybe the loose end of that wire became dislodged during my off-track trip at LRP and is now shorting out the fuse. I'll look at this again when I get back home. Any other ideas to chase down?

[kidrock]

+1. Most likely the wires to the deck lid light.

[dshepp806]

Just get an ohmeter on the light buld wiring and start moving/flexing things to see if the socket is seeing a short.

Socket(s) in good shape?

Best,

Doyle

[Innov8]

Thx Kidrock and Dshep.
I got home late tonight so I won't get back to it until tomorrow. I have an OHM multimeter but how can I check the sockets if the fuse blows as soon as I switch on the light...? I guess I don't really know how to use the multimeter...does it send it's own charge through the circuit?
The the deck lid light...is that on the driver side or passenger side? I can't find the wire (I have an aftermarket lid so there is no light fixture installed)

[Hugh R]

For the trouble, buy a resettable circuit breaker and jump the fuse connections until you figure out the problem.

[Innov8]

Thx Hugh R, I now have a good reason to buy a new tool! If I blow 8 amp fuse, what would you all consider safe increase without burning us lights or sockets? I would march the resettable circuit breaker up from the 8 amp but how high is too high amperage before I risk perm damage?

[T77911S]

check for a crossed wire. maybe they connected something backwords.
also look for pinched wires or wires that may be nicked.
remove the bulbs and the fuse. with power off, check the resistance from the side of the fuse holder to ground that goes to the bulb. if it is shorted, this will allow you to work with the power off and not blowing fuses
with power on and bulbs out, check for power on the pins of the 2 sockets and compare, make sure the same pin for each side has 12v on it.

[dshepp806]

Just don't connect that ohm meter to a hot circuit. Meters are sometimes unforgiving when doing just that.

Best,

Doyle

[donporfi]

Fuses are a safety device. Do not jump the fuse or use a larger capacity one.
Most likely there is a short in the line on the drivers side. Or when they repaired that side they left something loose.
Follow T77911S instructions.

[Innov8]

Thx guys! I picked up the circuit breaker this evening. Need to create the jumpers and then I'm going to try and find the short. Great punchlist T77911S! I will follow your notes and try not to burn out my meter! Watch this space and enjoy the holiday everyone. Patrick

[T77911S]

if you have a test light, i think they are better and you are less likely to blow your meter.
remove the fuse, connect the clip to 12v and stick the pic into the side of the fuse holder that goes to the ciruit, or the other way around, which ever is easier. if the cicuit is shorted to ground, the light will light, plus the bulb in the TL is a load so you are not blowing fuses or melting wires. as you remove bulbs or disconnect things, whatch for it to go out. i dont know the circuit you are working on, but try to find connectors to disconnect so you can isolate the circuit.
you can also use the meter the same way. one lead to the top of the fuse holder (fuse out) and one to the bottom. if it shows 12v, something is completing the circuit to ground.
TS electrical stuff is not that hard, just hard to explain while typing.

[Innov8]

OK. First thank you all for the sound advice. I just spent too many hours hunting this down with no luck. The test light was an invaluable tool...the best $4 spent in my tool box. I think that I failed to see the obvious here...read on.

As I mentioned the car has been popping fuses since it returned from the body shop a couple of years ago. For no reason, I never looked too deeply into the issue until late.y. Well after thorough poking around, disassembling all the connections I could find on the driver's side parking light circuit, I noticed that the passenger side circuit had a different colored fuse! Could it be that the shop didn't have the right 30¢ fuse and inplace of teh 16 amp (red) fuse, they used what they had on hand...8 amp (white) which I had continued to replace and replace. I've looked through all of my books and I can't seem to confirm that both the driver and passnger side parking lights take 16 amp fuses but i can confirm that I have had a 16 amp fuse in the passenger side and the lic plate light circuit since I have owned the car and have never had an issue with either...so I THINK problem solved.

BUT, I would feel much more comfortable about not melting my circuit if comeone could confirm that they run 16 amp (red) fuses on both driver and passenger side circuits. Thank you again for your help and advice. Patrick

[Innov8]

Update: Found the wiring diagram here: http://www.pelicanparts.com/911/911_parts/Electrical/911_electrical_82SC_Part2-1.jpg

The wiring diagram states that the fuses for the side marker/Parking lights for both sides should be 5 amp. I'd been blowing 8 amp fuses on the D/s and the P/s already had a 16 amp fuse in the fuse block...never has been an issue.

Could anyone comment on whether they use 5 amp or 16 fuses for the parking lights (Driver and Passenger are separate circuits). Thank you for your help.

[T77911S]

check the wattage of the bulb

[RoninLB]

they make a short circuit tester.

you replace blown fuse with gizmo and trace wires with another gizmo

it may cost $30-50

[dshepp806]

Originally Posted by T77911S

check the wattage of the bulb

+1.

Doyle

[Innov8]

thanks dshep806 and T77911s, I confirmed that the bulb wattage was what is shown inside the fixture... BUT when I compared the problem driver side with the passenger side (original), I realized that the side marker light was a different type. I set about converting the replacement housing to include the side marker fixture from the old, damaged housing. I just finished this and the whole thing works. I then changed the 2 fuses (going down from 16 amp to 8 amps for both the driver and passenger side) to be closer to the 5 amp required in the wiring diagram found in the shop manual.

I hope that this trouble shooting will help someone else in the future. Thanks for all of your help and suggestions. Patrick