RDS928S

Gents,
My early 86 928S started blowing interior light fuses(#18) on the fuse block like crazy. Today I went through (4) 15 amp fuses. What is the next step in diagnosing the root cause of the short?.

Thanks Rich

Bill Ball

Check the overhead light. It is famous for fracturing and then shorting againt the inner roof.

RDS928S

Bill,

Thanks.
I will check both the front and rear overhead lights.

rICH

Phil Silano

Rich,

I don't envy the task ahead of you. Hopefully you have a wiring diagram and a good meter.

I would start by removing all of the interior light bulbs, if the problem goes away then your short is probably in the "ground" section of one of the lights. If so, replace one bulb at a time until the fuse blows. That will at least isolate it to a particular light. This is probably not the issue, a fuse will usually not blow if the problem is after the bulb.

That means checking each of the "hot" leads to each bulb. The resistance between the lead and ground should be infinite. Disconnect the battery first. If any lead shows a zero or low resistance you have found the bad circuit. Then you need to trace tose wires to find the short.

Hope this helps.

Phil Silano

RDS928S

Phil,

Yes that will definetly help. Great advice-but not looking forward to that task.

Rich

IcemanG17

Rich
My car did exactly what Bill described...Just be careful with the clear plastic "hooks" that hold the bulb...they are pretty brittle....I just superglued mine to fix the problem! Been almost a year with no problems! When you pull the light out be careful not to lose the two little tensioners that hold it in place...I managed to drop one inbetween the center console and drivers seat! It was not fun finding it!
Brian

RDS928S

Brian,

good tip-thanks.
What is the procedure for pulling out the interior light housings?.
The light in the rear upper roof is already loose and a bit out of alignment. I suspect that is the one that shorts out when I hit bumps.(althought it could be any one of the others)

Thanks Again
Rich

IcemanG17

There is a little slot in the sides of the light housing...use a small flat tip screw driver to slip in there and push the spring tensioner back....then carefully pull it down...once you release one side the other should come out pretty easy!
Brian

RDS928S

Hey guy's

Thanks for all the advice. Could'nt have done it with out you.
I pulled the upper rear hatch/roof interior light out and it was a mess. The clear plastic "hook" section on the right side was completly broken off and the bulb was loose. Also the red wire to the right side was flooting around in the housing.
I removed everything and taped all connections with electrical tape. Ordered a new housing from 928 Specialist.
Replaced the interior light fuse and it DID'NT BLOW!!!.
I think we have it solved.

Regards Rich

AO

Same thing happened to me. Noticed a correlation between the lights and the fuse. Today I found that the rear hatch light had fallen out fo the socket and was causing the problem.

RDS928S

Andrew,

Check this out for weird 928 electrical maladies;

when the interior roof hatch light would short out and blow the interior light fuse (usually when you hit a bump) the seat belt/door open chime would sound constantly when driving, the rear power hatch release switches would not function, the lighted numerical automatic gear selector in the dash pod would glow very dim.
When the interior light fuse was replaced all these maladies cleared?.

Go figure.

That fuse is only for interior lights-right?

Rich

AO

For me, my radio works off it too, so if that fuse blows, no tunes! May have to change that around.