Circuit to Clock, Cig. Lighter, Glove box Lt. DEAD

[Gatornapper]

Need an electrical expert here............

I'm pretty good at electrical stuff, but cannot find circuit break in circuit that feeds the Clock, Cigarette Lighter (needed for GPS), and Glove Compartment Light on my 944 S.

The fuse, #8 I think, is fine.

Trying to trace the circuit it appears to run through the Instrument Cluster. Is that true?
Page 3 of Electrical Schematics, point 16. Seems to go to "Fuel Consumption" meter or gauge? What in the world is that?

Thanks,

GN

[944 Ecology]

Look for voltage at pin 42 on the K connector on the bottom of the fuse block. Trace from there...

Don't worry about the instrument cluster. The 944S does not have a mpg gauge.

Also, I believe it's fuse #11

[Gatornapper]

George -

Thank you! Yeah, think it is 11 - was going from memory.

And glad to know it does not go through the cluster. You guys have to be good if you repair clusters!

Parts: need one of the small knobs that go on bottom of original Baupunkt radio, Bass/Balance/Treble ones. Suspect you might have one laying around....

GN

Originally Posted by 944 Ecology

Look for voltage at pin 42 on the K connector on the bottom of the fuse block. Trace from there...

Don't worry about the instrument cluster. The 944S does not have a mpg gauge.

Also, I believe it's fuse #11

[944 Ecology]

Sorry, no radios left...

[Gatornapper]

Power good from fuse block - interior light works fine.

Can you tell me how the circuit is routed? Seems the overhead interior light would be the last point on the circuit.

Pull right panel, glove box, glove box light, clock & cig lighter to trace?

GN

Originally Posted by 944 Ecology

Look for voltage at pin 42 on the K connector on the bottom of the fuse block. Trace from there...

Don't worry about the instrument cluster. The 944S does not have a mpg gauge.

Also, I believe it's fuse #11

[944 Ecology]

Originally Posted by Gatornapper

Power good from fuse block - interior light works fine.

Can you tell me how the circuit is routed? Seems the overhead interior light would be the last point on the circuit.

Pull right panel, glove box, glove box light, clock & cig lighter to trace?

GN

Don't know... never had a problem with that circuit, so never had to figure out the routing. I assume that it is somewhere in the dash.

[Monkey Wrench]

lighters draw big amps and sometimes stick so Ive seen those blow fuses often. If you dont smoke you may never use it but you might use it to run other things too.


check with your meter, not only the fuse but put a probe on either side of the fuse from the brass connector. often the fuse is good but fuse holder is corroded. pull the battery cable off and you can go deeper maybe use a brush and contact cleaner. near the fuse will be a tab that the spade connector pushes onto wires can fail at the crimp connector or the spade can corrode. sometimes that spade connector is not right adjacent the fuse as the same source can feed more than one fuse so look nearby too.

specifics of porsche wiring , how it's run. I'll leave to those with more experience on this car.

you can check a fuse with a meter sure but also pull it inspect near to it for corrosion. Its not unusual for that style of fuse to break , especially the small ones.

with ignition on the fuse should be hot on both ends , you can check that as well as continuity through the fuse.

another car I have uses those typical plastic push in fuses. I had a lighter gizmo to charge my phone in the lighter socket. I had bought some fuses that have a red LED that lights when they blow. I found that even when the fuse blew, because the fuse itself had a LED I guess it still conducts somewhat. I was confused at why , if the fuse is blown that the LED still came on on this USB adapter in my lighter socket. I think it was feeding enough microamps through the "blown fuse" to light the LED in my adapter even though that fuse had blown.


Ive never seen fuses of this German style include the LED gizmo. I guess under ideal conditions having a blown fuse light up helps, I found it only confused me.

I think the LED feature must be relatively new. I hadn't seen them before. I decided I dont like them either. I dont know if they will or do make this euro style of fuse with that feature, but if they do, just a heads up..

sometimes a digital meter can detect a voltage even if there are only micro amps of power actually available. Then sure it's technically hot, it has 12 V but if you try to run anything off it then it wont do much for you since that tiny bit of current isn't enough to do actual work like light an incandescent bulb. ive heard this referred to as an "erroneous voltage"

sometimes an analog meter ( with a needle and pointer) work better visually or a test bulb wont give you a funny reading with 12 V and almost no amps available. I've seen that scenario throw people off.

[Gatornapper]

I'm an old EE and have decades experience trouble-shooting all kinds of electrical/electronic/computer devices.

Usually can find problems quickly & easily. If not, then all I need is a good schematic drawing. The schematics in Porsche drawings leave a lot to be desired, especially older ones. Tons of information missing.

I'm just trying to avoid having to tear the whole dash apart to find the break in the circuit, but may just have to do that.

I'm thinking the 12v + line is indeed broken somewhere behind the cig lighter. Getting to it is not fun. Saw video on how to get to clock to put new digital face on it - which I will do someday - so I know how to do it.

Was hoping someone would have experience in knowing how this circuit is routed. Again - have power at interior light.

I need the cig lighter for 12v + simply for my cellphone charger.

GN

Originally Posted by Monkey Wrench

lighters draw big amps and sometimes stick so Ive seen those blow fuses often. If you dont smoke you may never use it but you might use it to run other things too.

.......................
sometimes an analog meter ( with a needle and pointer) work better visually or a test bulb wont give you a funny reading with 12 V and almost no amps available. I've seen that scenario throw people off.

[944 Ecology]

Here are the wiring diagrams... I will make them available to download for a week...

https://drive.google.com/file/d/1Jr5Bmub4csCuXOGAbSJsd680MCWkPxc6/view?usp=sharing

and, this primer might make reading the later diagrams a bit easier:

A quick primer on reading the Porsche wiring diagrams

[Monkey Wrench]

I would think the lighter itself probably has a connector that's accessible if you can easily pull out the socket for it. Often they are full of tar crud so bad connections inside.. maybe that is obvious but I;d pull the socket and check behind, rather than inside the lighter socket itself . most Ive seen have either a short wire and a connector or a spade connector on the back of the socket. you can check with a meter if the socket is grounded , it should be.

that feed wire might be an easy and obvious place for a radio installer to hack into, to get power..

I stuck one of those phone charge adapters in my van and through the back window the red LED can be seen from a block away, kind of looks like it might be an alarm or something so I leave it on. the draw is very minimal.

I cant; imagine the power wire going "through" anything, it might run several things in parallel But I'd seriously doubt it has any series connection. It could be something like where the power is carried through from one spade connector to another spade connector, being daisy chained at a terminal point. Then the spade connectors and wire might be in series but not the loads that draw from it. In that case a wire could come off.

if access that hard, would fishing a new wire from the lighter to the correct fuse be easier? I dont see why a parallel connection right from the fuse terminal would be any different electrically. Im sure its just a wire pulled off but is it worth taking a lot apart to make it correct? a consideration for me would be what if I break some plastic part during my hunt into the depths of the dash for a wire that probably got pulled off it's connector.

if everything run off that fuse had it's own separate wire to the fuse, That's not different from an electrical stand point, it just saves wire and maybe keeps things a bit more neat and tidy.

an orange wire with yellow tape wrapped around it like a barber pole would appear as it was " marked "to any other troubleshooter that came after you..
you can also attach note that "the wire isn't original" so as just to not confuse anyone else, Then if you do need to go all into the dash it would be a simple matter to connect it and remove that non original wire.. if the only issue is that the lighter's not working.

often where the lighter is mounted it is surrounded by plastic so it also needs that ground wire.

Porsche dash specifics I'm not qualified help with but I'm booked for some sessions at school of hard knocks, so I'll get there.. ;-)

[Gatornapper]

WOW! THANK YOU!

All I have is Haynes Manual which leaves a lot to be desired.

As an EE, I've been reading Porsche diagrams for years, and had these documents for my 1980 924 Turbo I restored.......so glad to have them for my 944 now.

Main challenge is finding the correct page!

GN

Originally Posted by 944 Ecology

Here are the wiring diagrams... I will make them available to download for a week...

https://drive.google.com/file/d/1Jr5Bmub4csCuXOGAbSJsd680MCWkPxc6/view?usp=sharing

and, this primer might make reading the later diagrams a bit easier:

A quick primer on reading the Porsche wiring diagrams

[Gatornapper]

Page 151 is exactly what I needed - shows circuit routing from clock to glove comp. lt and for cig. lighter - have some studying to do now........

Thank you so much.

BTW - I was never suggesting any circuits were in series - only wanting to see connecting points of circuits where breaks could be. This diagram has them.

GN

Originally Posted by 944 Ecology

Here are the wiring diagrams... I will make them available to download for a week...

https://drive.google.com/file/d/1Jr5Bmub4csCuXOGAbSJsd680MCWkPxc6/view?usp=sharing

and, this primer might make reading the later diagrams a bit easier:

A quick primer on reading the Porsche wiring diagrams