how to trace out electrical problem.....please help me

[jkcrewsn]

I don't know where to start. Sometimes my tach is screwy.....sometimes my turn signal is slow, sometimes fast....but what really bothers me is with the car off and the doors shut when I try to put a fuse (15 amp) in my interior light fuse holder it blows. So where to start? Anyone have any ideas what could be the problem, or what to check first? Thanks so much.

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Jeff

'79 930
http://www.pelicanparts.com/gallery/jkcrewsn

[jkcrewsn]

I just read the thread below...could this be a voltage regulator problem too??


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Jeff

'79 930
http://www.pelicanparts.com/gallery/jkcrewsn

[Joeaksa]

Jeff,

Some of these are easy...

>>sometimes my turn signal is slow, sometimes
fast>>

This one is a burned out or loose light bulb in one of your turn signals. When you put the turn signal on, check which side is flashing faster and when possible get out and look at front and rear of the car with the switch on and its flashing double speed. One of the bulbs will NOT be flashing...

>>but what really bothers me is with the car off and the doors shut when I try to put a fuse (15 amp) in my interior light fuse holder it blows>>

This is easy to figure out but could be more difficult to fix. You have a dead short somewhere in the wiring to the interior lights to the car. Start by taking the light fixture out (you did not say if it was a Targa or Coupe) to start. Look inside the place where the light(s) fit and check if the terminals were hitting on the body, shorting out. If you do see signs of arcing here, leave the light fixture hanging out, replace the fuse and if it then stays OK, you have found your short.

If this was the problem, then put some tape or other insulation over the connectors and replace it in the car. I have seen the terminals on these light fixtures bent too far out (almost 90 degrees) and they then made contact with the body, and shorting out. If this is the case, gently bend the terminal to a more horizontal angle and replace it in the body.

If the fuse then blows again, you get to track the wiring back down and you will find a short somewhere...

Hope this helps...

Joe

[jkcrewsn]

Thanks Joe. I will look for the short, that makes sense. The thing with the turn signals ... I thought about the lights out, and I do indeed have a brake light out, but as I said, its not a constant thing. Sometimes they work right, and sometimes they act like they are on crack. But I will change the brake bulb (with fingers crossed), and hope it helps.

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Jeff

'79 930
http://www.pelicanparts.com/gallery/jkcrewsn

[Planter91C2]

the bulb may be good (check it), if it is then take some emery cloth and polish the contacts in the bulb socket. this happened to me once and the socket had some corrosion on it. once removed everything worked fine.

[MJ]

I had this problem with the bulb once also. I went a step farther though as the socket and contacts were worn (older 911). I had to solder an extension blob onto the bulb's contacts to get them to make up well. Worked for me as the sockets are pretty hard to work on. The only down side is that I probably have to repeat this whenever a bulb is changed.
Marty

[Roland Kunz]

Hello

Any problems with the ignition switch ?

Is your blower working ?

Your cigarette lighter ?

Ground wires checked ?

Light bulb in the trunk renewed lately ?

Grüsse

[Rick Lee]

I had to replace the turn signal switch on my '87 911 Carrera last week. All worked well for a day and then the left rear signal went out. Always clean the bulb contacts before assuming it's something else. Mine looked clean, but as long as I had them out, I ran a steel-bristle tooth brush over all of them. And everything worked fine then.

[Kurt B]

The interior light, glove light, and trunk light are on the same line (so is clock). Often the trunk light wiring gets pinched in the shock or thereabouts and shorts. Mine did this and burned all the wiring (fuse didn't blow for some reason, probably too big). Anyway, start there.


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Kurt B
1984 Carrera Cabriolet
911 Page
carrera_cabriolet@yahoo.com

[RoninLB]

simple 2 part tool available to track shorts, about $40........Ron

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RoninLB

[Joeaksa]

Kurt,

Good call! If the wires you mentioned are not pinched somewhere, I wonder if the clock might be shorted internally? Easy to check, pull it out and disconnect the power wire...

Joe

[kepperly]

Hold it, Hold it!!
Do not check for a short by replacing fuses
if you want to keep from selling your car to
your insurance co.. Get a true digital, not
anolog metre and learn how to use it. Get some alligator clamps and hook up the meter
from ground to the bottom of the fuse holder
that protects that circuit.(after you remove that fuse). It should read infinite resistance. If it doesn,t then you have a short and are on the path to "tracing" down
your problem, not burning up your car!! Also
get a wiring diagram and invest some of the brain power you have that allowed you to earn enough to buy a Porsche into understanding it. I,m in the electrical bussiness and that would be like an electric
contractor looking for the right circuit breaker by shorting out a conveinance outlet.
your banker would be proud
keith