Jim Chambers

History: Right front signal out. Checked bulb, OK. Checked fuse, not OK.
Replaced fuse. Front still out and now back out as well. Tried new flasher. No change. Rechecked both rt. f. and rt. r. fuses. Neither blown. Used test lamp at each right fuse while signal switch on...only very dim flashing light.
Did same on left fuses while flashing and test lamp flashed brightly.
While checking to make sure both rt. fuses were solidly in place I touched the rt. front fuse and it was very hot, too hot to touch, but not blown.
Where to look next? All thoughts welcome.

Mrmerlin

put new fuse and deoxit 100 on the fuse blads you fuse connection is dirty or loose or both

Alan

You don't mention a year - are you sure you have the right bulbs installed?

What is the history - was it working correctly before? what has been done since?

Any issues with the combination switch on the steering column?

Alan

Jim Chambers

Only owned the car for 3 weeks. Car is a '78 US. Certainly could be the switch (really hope not). Not sure how to test that, but it works left side and until lately also worked right rear. As I mentioned, the switch will send juice to the right side fuses but only enough to make a test lamp glow rather than flash brightly as of the left. I'm sure bulbs are correct.

Callum_GT

sounds like the grounds need cleaning to me

dr bob

Jim--

Spring the Big Bucks for a Rennlist membership, and you can add a car profile in the signature area. Beats having to type in the same info into every post.

When your car comes by for the shift linkage work, we can get out the meter and find exactly where the turn signal current is slowing down.

If one of us can man the camera and the other do the meter, it would be an interesting lesson to share with the group. I have a camera...

Jim Chambers

Sounds like fun Bob.

Which ground terminal do I check? Please don't say "all of them" (though that would be a good idea). I just want turn signals on the right side now.

Just joined for 2 years....already noted.

Jim Chambers

Just did a recheck. Fuses are well seated and terminals are shiny new looking, fuses are new as well. Still only a glow from test lamp on both right side fuses, brightly flashing on left side. Rt. front fuse gets very hot very soon when signal lever on. Wonder if the entire circuit is hot as well! Should I be looking behind the relay/fuse panel? Hate to open that can of worms.

Thought about checking behind the rt. front light assembly but can't figure out how to get there. Thought the light bucket would simply unscrew but not so.

928 DesMoines

For what it is worth, I had a similar problem. Everything looked good/checked out. Eventually, I was spraying deoxit in the bulb socket and tail lamp harness connector to see if that was the problem, and yes, the innards of the bulb socket just crumbled/flushed out. I still have to get the new socket; but I think that was the problem for me.

Mrmerlin

I think that before you do further testing you need to run a full lamp cleaning inspection this should take a few hours to complete,
you will also need to remove the front fender block off plates.
you want to inspect the side marker lamps and the wires and the harness where it comes out of the chassis just under the headlamp look for a damaged harness from the the wires being pulled too tight.

NOTE did you install good fuses or china knock offs,
if the fuse is getting hot and the connections are clean then you may have installed a set of the non blowing china fuses... DrBob can advise

Jim Chambers

The fuse that is "hot" is from a box I bought at NAPA, Buss brand, manufactured for Balkamp Inc, made in Taiwan. Do they qualify as "China knock offs"?
I will swap for one the "old" 8's tomorrow and see if it still gets hot. I think you are saying it should "blow" rather than just get very hot.

Front fender block off plate gives access to the side marker/signal harness? This all started with non-op rt. front signal and a blown fuse for that lamp. Sounds like there is a short which blew the fuse and only heats the replacement. Correct?

ltoolio

Do 'em all. Doesn't take terribly long, and might help mitigate any still-to-be-found gremlins.

Mrmerlin

Jim yest to everything you posted post 11

dr bob

Jim--

We'll get it while the car is up on the lift. It will give me something to do while you change the linkage bits.

For those playing along at home:
Each of the turn signal "loops" is fused individually. Service/diagnosis starts with removing the bulbs and inspect/clean the sockets as needed. Then check continuity to ground from the fuse holders with fuses and bulbs removed. There should be none. The symptom of hot fuse with low test light intensity suggests a 'partial' short to ground between the fuse holder and a bulb, or a high resistance in the fuse holder itself.

The Buss/BK glass fuses may or may not be OK. The bullet tips of those fuses are chrome/nickel, vs the original copper foil in the ceramic/plastic fuses. Resistance in the fuse connection itslef will melt/blow the original fuse before it damages the fuse holder or the plastic CE panel behind it. In addition, the blades of the fuse holder are beryllium copper, and "self wipe" when the copper fuse is rotated in the holder (part of annual maintenance ritual on early cars...). Not so much with the fuses with the plated ends.

In many years of tracing electrical issues in the pre-mid-eightees Porsche (and other German cars) with the ceramic fuses, I've had consistent good luck with the original style fuses. Replace in kind if you possibly can.

Bad News is that I gave my massive collection of spares to Dan Bise way back when, as he was chasing issues in his earlier car at the time. Good News is that new ceramic fuses are still available.

Jim Chambers

Thanks Bob. Here is a pic of what I have. On the left is a fuse from another location in the panel, assume it is German. On the right is the "made in Taiwan" fuse which came in the box shown. It is the "hot" one. I have yet to try the other fuse to see if it will blow, showing the short. I look forward to your help as always.