NB 993

I just noticed this dim flicker (see video), it happened yesterday for the first time since I own the car.
I attached it to the battery tender overnight and checked it again this morning. The tender was actively charging and it was still doing it even with the key out of the ignition. The car starts promptly with no issues. Battery is 3-4 years old at most.

I pulled a USB charger/FM transmitter out of the cig lighter and it stopped. I am going to go check on it again in a few hours and hopefully that's all there is to it.

The only new electrical addition is an Immoblock that I installed instead of the gong relay. will remove that next if the flicker returns.

Car is a 96 C2, low milage (~38k) and had a full check up including the belts last week, they all look fine to me and are on good tension. Read about the alternator rabbit hole but hopefully it's just that stupid FM transmitter.

Had anyone seen a small device like this doing it? Any other suggestions?

Jlaa

Can you check your battery’s ground and pos connections?
Also, how many volts are you measuring your battery at, while at rest, car off, battery tender unplugged at least one hour prior?

NB 993

Thanks for the response. I’ll get a multimeter and let you know.

I checked it a few times today and went for a drive, the flickering has stopped actually. Hope it stays that way.

boomboomthump

Odd that it is doing that with the key out of the ignition. Not sure how that's possible.

FYI, that warning light is not for the battery/electrical system itself. It's a warning light telling you whether the alternator is charging the battery or not while driving (has nothing to do with charging via a tender). It does so via the alternator belt tension sensor. If your belt breaks, that sensor (it's a wheel do-hickey on the left, lower side of the engine belts) it will no longer make contact and then the light comes on to warn you that you are no longer charging your battery while driving.

An intermittent flicker (while driving) normally means that either the alternator belt is loose or the switch is possibly going bad. Now why this is happening when the car is completely off with key removed, no clue. That shouldn't happen, unless I'm missing something.


BTW, if you want to test that sensor wheel, you can unplug the connector and bridge the connections on the harness side. That's actually what's done to ensure that light isn't lit if you convert to a Clewett pulley setup.

pp000830

Did you replace the bulb with a led?

NB 993

I replaced the exterior lights (headlight and rear) with HID/LED but not the dash. Flickering stopped before I made the changes, I wanted to wait a few days before changing anything electric but it was one nice day we got in a while to get some work done on the car.

Currently all is functioning ok and the blinkers are at normal rate with the flash relay swap from Tor. Keeping the battery on tender u til I can check it with the multimeter tomorrow.

budge96

If the light was flickering or on with the key removed I believe the only explanation is a short at the alternator , possibly time to pull it and check the wiring off the rear and if any associated wiring is frayed .
As far as I know that's the only place the dash bulb could receive positive power the charging cable returning to the battery...Bert

orangecurry

Before going mad with anything else, if the battery negative cable is the original 25 year-old item, replace it - with a quality one. I'd find one from an electrical/cable specialist rather than just going to Porsche, as the OE quality may not be being replicated by Porsche's current offerings. (there's a joke in there....)

If the earth cable's not the problem now, it will be soon with something else.

This advice is for every old car of course - the 993 is nothing special when it comes to electrics.

boomboomthump

Having just sourced a new one via Porsche, I'd love to hear a compelling argument as to how the original design is superior?

The newer ones are better and frankly how they should have come from the factory in the 90's, instead of the even decades older design of bare ground wires that get corroded and frayed easier, leading to electrical problems and the need to replace them. The new ones are fully insulated and sealed, including the ends. No bare copper exposed at all.

pp000830

I know it's a long shot but maybe your car was channeling a local FM radio station and the light was pulsing with the music, you know like the lights one sees at a wedding when the DJ gets going?

NB 993

quick update:

So the battery reads are fine, 12.7 at rest and 14 at idle. Car operates fine, fires up at first crank with no delay whatsoever.
The negative strap is actually updated by the PO and it's totally clean on both sides with perfect insulation.

Have gone on a couple of drives since I notice the battery light and it never recurred to the extend of when that FM transmitter was in place, there might be a 0.5 second delay when I turn the car off for the battery light to go off than the rest of them, maybe I am looking at it too much!

I hear a faint hissing sound when the engine is running (see video), it looks like it might be from the alternator sensor (now that I know where it is) or maybe belt slipping but it could also be what it's supposed to sound like. Would appreciate more seasoned folks chiming in. I am a complete rookie.

NB 993

and tonight, the alarm went off spontaneously.
Now the battery light is constantly on with the key not even in the ignition and the fob is not working. when I press the button the red light in the doors, flashes twice quickly but the door locks don't open or close. I thought it's a dead battery but the volt meter reads 12.5 still, just like prior.

I am confused. something is off electrically.

I pulled the ImmoBlock since that's the only addition recently prior to all this and reconnected to the battery tender until I figure it out.

jay@EZimmoblock.com

NB -

1) Power to light that warning lamp comes from relay R11 (the 15e bus).
2) Relay R11 should only be on when the ignition is on.
3) IF relay R11 were stuck on (or being driven on when it's not supposed to be by some unknown path) all sorts of strange (and unrelated) things can happen because the 15e bus goes to a ton of places.

So...a simple test: with the car off and warning lamp ON, pull relay R11. Let us know if it goes out. BTW, there are a number of that same type relay in the the fuse box so if the warning lamp goes out, try swapping one of the others in. If the warning lamp stays out, the relay is bad, problem solved. If it comes back on we'll need to find what's turning it on...

AR_Motorwerkz

Hopefully nothing serious.

NB 993

Thank you all for your inputs.

I woke up to a completely dead battery this morning.

so I just pulled the negative terminal and left for work. Will do what you suggested Jay if possible with a different battery.

unsure what could’ve caused it. I had a simple inspection done 2 weeks ago with few electric additions (immoblock and light upgrade from Tore) but the light flickering started before any of the additions.

will report back.