Printed circuit burned on trace going to lower right pin two
 

My printed circuit burned the trace going to lower right connector pin 2 "Masse" or ground.

The 5th pin from left reads masse as well but has a differnt color wire as pictured.
This resulted in my cluster lights going out. I am supicious of the dimmer potentiometer and the cluster connector wiring. I changed the blue black wires on the pot to go to the lower connector as they were on the upper when I got the car with non-working circuit card.

Should pins 2 and 5 from left on the right cluster connector both be brown wires as the wire is in pin 2 pictured.

Sorry, first post so will just throw some pics up.

http://forums.pelicanparts.com/uploa...1296876331.jpg
http://forums.pelicanparts.com/uploa...1296876351.jpg
http://forums.pelicanparts.com/uploa...1296876468.jpg

Car is 1980 Euro S by the way and for clarity, I burned mine in the exact same place as the burn where this jumper is, from another post by Rupesy..

http://forums.pelicanparts.com/porsche-928-technical-forum/584773-79-speedo-not-working.html


http://forums.pelicanparts.com/uploa...1296876752.jpg

Have you checked in your console, near the base, in vicinity of ashtray? I've found several cars with heat / fray / chew damage in that area and its the same circuit -- could be contributory.

Any other thoughts on cause?

Thanks for the quick reply. I will check there as well. I saw some loose ground wires brown / white under steering column as well as some creative wiring and use of colors by PO. Cleaned battery, ground strap, and contacts, went looking for the ground spot in the engine, but i think I located the positive block on passenger side fender above compressor. Cleaned that as well.

I am suspect about the positions 2 and 5 "MASSE" on the lower right cluster connector with two colored wires as in my cluster connector pic. The wire on 5 is not the same color.

When I got the car, the cluster did not work but the tach and right guages.

How can I eliminate the potentiometer dash dimmer, just join those wires blk / and black - blue. Mine has that 4 pin molex connector coming off the potentiometer and washer button.

Yes you can bridge across the potentiometer for the lights.
There might be another one on the opposite side for intermittent wipers?

yes there is another one for intermittent, but it is yellow / red and yellow pair, looks ok from what i have seen

I'm not sure if you have a wiring/current flow diagram, it can help you trace. These may help...Manuals...scroll down to find what you need.

Thanks JhwShark. The cannell site is familiar, I downloaded these a long time ago for the 89 S4, but haven't been back since. I'll report back after I get back out to the garage this weekend.

I sure hope I don't have to trace the cluster connectors out, but printed circuits are not cheap and it seemed to jump from $120.00 to $287.00 for whatever reason...

Have a 930 S wheel on the way, but can't put it on and drive the car due to the wiring issues. At worst if it fries again, it is no pod lights, and temp guage flaky. All others were working after the scorch.

Good idea JhwShark. I was thinking of the shop manuals, and combing through them is cumbersome in pdf format to find what you need. But the current flow diagram is great. I just wish I were better at these diagrams, I like pics and layman descriptions. But I am cheap, so I will be motivated not to fry another circuit trace!

Well as for lead numbers, the MASSE contacts are pins 7 and 11 on the lower right connector to cluster.

My grounds match up, so i cleaned their attach points and will check fuses for illumination. I feel that there must be a hot wire in the ground circuit with a crosswire somewhere on the switches.
http://forums.pelicanparts.com/uploa...1297015214.jpg
http://forums.pelicanparts.com/uploa...1297015385.jpg
http://forums.pelicanparts.com/uploa...1297015424.jpg

note the odd 4th switch taped in blue and spliced into the leads for the dimmer pot and intensive wiper push button
http://forums.pelicanparts.com/uploa...1297015550.jpg

i think it may be one of these two, the dimmer pot or the washer push button, i have
http://forums.pelicanparts.com/uploa...1297015651.jpg

meant to have my printed circuit lower right pic included as well next to the connector.... The MASSE loop is from PIN 11 and PIN 7 which matches my connector and i did a connectivity check with tone and connectivity tool

http://forums.pelicanparts.com/uploa...1297015933.jpg

What's that crazy cobbled-up trailer light harness doing there?

There is an extra Euro light socket taped up inside all these dashes.

Would that be a freebie from Porsche? lol

Why is it half wired up?

Its for the rear foglight. All the cars got certain remnants of wiring across markets.

On the Euro cars, the bottom left switch is the rear foglight. That's the fixture you found. Usually its tapped with old beige masking tape.

The odo reset switch is replaced with something under the dash instead.

Thanks, I do know my rear foglight worked prior to going in. That is why I was confused about the push buttons, because I believe one is for trip reset and one is for intensive wash. I know that some cars have two pushbutton switches intensive wash and trip reset and two potentiometers dimmer and wiper delay. While in holding pattern for fuses, I was in the panel and found at least 7 fuses that are coated in white paint or corrosion. Not sure if they are dummy fuses, but I have only 2 "not used" slots in the 80 Euro S.

I took a dremel with a nice hard rubber disc which was thin enough to do the middle and both ends of the bullet fuses until they had a nice shine and are now conductive. 7 and 13 were not used if I recall, but I cleaned about 5 others. I think 11 and 12 are for instrument lighting among a few other things. Both looked shoddy, but they have continuity now at least. I am soon going to reapply power to the cluster with the new printed circuit. I just want to be sure there is no hot line in my ground circuit.

Is there any risk in putting the wrong white switches in the wrong white plugs for the rear fog light and the fog light switches? I am referring to the white switches you see when you pull off the buttons in position 2 and 3 on left of pod.

Thanks...good info diferentiating between Euro and US...good to know!

Where did you get a new printed circuit board? It looks like I need one also. My rebuild didn't work even though it looked like it should have. I have several gauges not working and no instrument illumination. All the warning lights work though. There is a place in Greensboro,NC that is a well known VDO rebuilder. Gunar

Check with 928 International for your the board...

@ gbgastowers

Yes, I got the printed circuit here at pelican, nut the price is way up from weeks ago. It more than doubled to $287 now. It is for 79-81 and you were 82.

928 International - Printed Circuit 79-81 - Printed Circuit 79-81 - shop.928intl.com

I will keep my eyes peeled for you.
I may have some parts for you once I get mine working.

Updates:

I just replaced all fuses tonight and properly replaced all oddball Amperage fuses. There were 25A fuses in 8 slots which is probably why it allowed the damn thing to fry my cluster.

I used the rubber disk dremel attachment on a lower speed and cleaned every fuse socket. I cannot stress enough that I was astounded that so many fuses where a corroded white powder coated look with no continuity, yet were somehow "working" systems. I first cleaned them, then just replaced the aluminum fuses with the newer brass / ceramic bullets.

I closed up the fuse panel. Getting closer to applying the "All Spark" to the cluster!

Here are my shiny new fuses.http://forums.pelicanparts.com/uploa...1297151207.jpg

Here is the german cluster that I am installing in place of my mph euro cluster
it came in rough shape,
http://forums.pelicanparts.com/uploa...1297151331.jpg

I used mothers and meguiars headlight restoration, only the foam rotary on a drill, no sandpaper and it looks new! I love the red needles, just like on my 04 2.7T Audi!


http://forums.pelicanparts.com/uploa...1297151445.jpg

Update:

-Tried new cluster, replaced all fuses.
-No tach, (will try with known good)
-Fuel registers full, voltage registers.
-Warning lights seem to work, handbrake, Stop Brake, etc..
-One 3W on but no others.


This cluster was from a german 80 manual / mine previous is 80 S automatic.

-I disconnected fuse 23 which controls interior lights just to be sure there wasn't something interfering.
-My headlights work, external blinkers work, fogs, driving, rear fog all work. Car starts and runs. No dash lights with lights on or off, well one light is on bottom right 3w.
-I shorted the wires black to black / blue for the potentiometer (dimmer) left side to bypass it, no change.
- Mileage Reset Works - Tested the black pushbutton under my dash for mileage reset and it works.
-Turn signals click and work outside, but not in cluster light


If anyone has a picture of the wire pinouts for an 80 Euro S as they are on the cluster cable I would appreciate it for comparison. My 3 printed circuits all read tacho for pin 1 left connector, the flow diagrams specify this wire as green or something. My wire is not green.

I think the PO has moved things around.

1. Does anyone know which leads on the L R and Center connectors would give the dash illumination and what their wire colors are?

2. Any other ideas as to why it is not working?
If bypassing my potentiometer did not work, then maybe these wires have no current eh?

I don't think these early 78-81 clusters have gear position lights or indicators in automatic or manual.

tacho: pin 3M, green

dash illum: pin 12R, black/blue

did you confirm the ground, which is common for most of the lights, is clean at the body?

What diagrams are you looking at?

What is the condition of the signal processing box mounted underneath the dead pedal?

Hi Landseer
Thanks for responding

I am using the 80 Cannell.co.uk guide because I do not have an 80 Euro S flow diagram. I will try to contact porsche and see if they have something. Then cross referencing with 79 and 81 for comparisons and likenesses.

Tacho is 3m Green. So position 3 middle connector? The printed circuit label says the word "tacho" on L1, but the wire going there is not green so I will check 3 middle.

I went looking for the passenger side ground, in the wheel well, but fell short after removing the flap there, did not see it. I found the 14 pin up front and cleaned that. Cleaned the negative battery ground strap and all battery connectors. And cleaned the ground under the steering collumn. There were at least 8 brown wires going there. I will hunt down the other ground locations.

I do not know of the dead pedal or where it is yet.

Well, trace from pin 11R fried in the exact same spot again as in the picture.


The tacho has a green wire on 3M
The lights have indeed a blue/black on 12R
- I am getting continuity from this pin to the ground in the steering column with power off or on.

-Odo reset works and all lights work on exterior.

I dont think that is correct, so I must have a hot wire on the ground circuit right?

I do think the dash lights are wired correctly except there is a hot signal burning the lead off 11R an inch past the first bulb. So I still get that one rightmost 3w bulb only illuminated.

I now know the other ground location is behind rear right wheel, i was looking at passenger front wheel panel first.

If you are burning the trace off you have a short circuit someplace "downstream" of the failed area of the circuit. If I understand you issue you also have 2 of the 3 bulbs not lighting up in the instrument illumination? I would pull each of the bulbs and verify they are good by hooking them to a 12 v battery....a small alarm battery from say Radio Shack is a reasonable choice.....but don't stick it across the + and - terminals on the circuit board untill you have found your short. A bulb can fail "shorted" by the way, not often but they can.

Another suggestion I have is get the subject WSM wiring pages enlarged. I had mine printed out at Office Max in 18"x24" format, I think I will have them printed 24x36 next time. Makes troubleshooting a bit easier. I had about 11 pages blown up to the 18x24. Cost me a $1.60 per page...I am guessing that the UK has similar office print shops...

As others have pointed out there are other bulbs in the circuit that are controlled by the dimmer, like the clock light, the gear selsctor indicators on an auto transmission car, the radio backlight, and the ash tray light...

The net of it the 7 conventional "ground points" are not your problem but rather there is a point in the circut that is grounded that should not be.....and that is causing the foil to burn off your circuit board......

A lot of the dash lights trigger when powered by the Central Warning system.

Isn't there a fake pedal on the floor by driver's feet? Foot rest? Take it apart, the central warning box should be hidden inside. Its part of your circuitry.

I'm looking at USA wiring diagrams because Euro and USA shared most of the wiring and the CE panel.


Dash lights also are on the same circuits as the lights in the console I think. Lots of times mice or bad stereo installers mess-up the purple/black or blue/black wires in the console and cause the problems for the dash lights, but usually the fuse blows. Do you have the right fuses in the right slots. Never use an overrated one.

Looking at the '80 USA wiring diagram the 3 lights in question are pretty much directly in and directly out of the panel itself, with the positive connection being 12R and the ground being terminals 7R and 11R with 7 and 11 being connected together with an external jumper between them. I suffered a burnt trace of these lamps in my '84 also, but it was a result of me accidently shorting across the + and - conductors on the board. A lot of the rest of the instruments use the same grounds, since they are working correctly it would seem the cause of the burning conductor would need be on the other side of the bulbs but still on the board itself? Any possibility some one has put in the wrong bulbs for the 3 instrument illumination bulbs? Like maybe 1.5 or 4.5 vdc bulbs? Something is drawing excessive current and it would seem to be in the bulbs or the sockets themselves....

Thanks Tmpus and Landseer. I was in there a few hours today. I rebuilt both the german cluster and the english euro cluster. I repaired the burned trace from R11 just past the 1st immuminaton bulb.

If I put a continuity checker on R12 and R11 / R7 ( the two grounds) it lights up green meaning continuity. I do not know which ABC terninus on the CE the blue / black on R12 goes to. I tried a tone signal from my tester, but it goes everywhere since there is ground short.

I am fairly certain that the issue is with the blue black on R12.

I replaced all 3 illumination bulbs with 3W bulbs. I tested for illumination with a 9V battery each bulb before putting in. They do light up.

After repairing the burned trace, I used the tester on the middle speedo ring and the R12 pin. I have continuity across the cluster. I used a circuit pen, wasn't easy, I put tape behind the burn, then drew a new trace, then covered with tape on the front.

Do you guys know where the R12 blue / black cluster illumination lead terminates in the CE panel. If I can find, I can run a new one that I know is direct with no ground detours.

I still haven't found passenger side ground. There is one in the rear right hatch. One under steering column. Is it by the 14 pin under the hood?

Side note... Found the leveler switch
I had an 89 S4 which had hatch release left of the drivers seat. This 80 euro model has a dimmer switch that rotates right and left rather than lifting like the hatch release.

OK.

Ground bolt location isn't necessarily corresponding to the item grounded.

You should remove the wooden covers and passenger side tray above fuse box.

The grounds are on the firewall above the fuse box. Umm, same for S4. I can see the brown ground wires in the picture of your panel, above it.

Its more efficient in hunting down any electrical problem on a 928 if you have first done 4 things.
1. Remove, polish, inspect and re-fuse the CE panel. Confirm right relays in right slots and change the critical relays with new. (and seal the fan while in there)
2. Clean all grounds.
3. Remove the console side panels and look for rodent damage or melts.
4. Remove all aftermarket wiring

You did some good work with the terminal cleaning and refusing. Did you remove the panel to do it? It needs to come out now. Use of high amp fuses and melts means you could have melt cross circuits on the back of the panel, rendering any further work useless. If you had removed the panel (which really isn't as bad as it seems) you would have discovered the passenger grounds in the proceess. It will force you to look closely at each of the wires in each of the colored distribution plugs at the base of the panel. Great evidence there if you see insulation decay or melt.

On your panel picture, you still have one scabbed vampire wire connection on plug to the left, A or B?. Rid your car of that crap.


Read my 16V ground thread for more (at least skim the pictures, they will help some).

The wiring diagrams do a pretty good job of mapping the circuits. They define the grounds for each circuit, too. You just have to spend some time looking closely at them, all of them. It will save time in the long run.

I'll take a look and see what I can find regarding the instrumentation wire path to get you started. I think clock light and cigar lighter illumination also run on that circuit. That's where I've found problems on 4 different cars.

On 4 cars I've found badly melted wires. 2 have had wire melts behind the panel causing intermittent short circuits. All 7 have had corrosion on grounds. Very common occurences on cars that have lived lives where it rains.

So, interesting circuit.

I took a cursory look. Confirm what I say with diagrams.


Fuse 11 is 8 amp.


(Black / Blue wire color is used for illumination and other things. It is not exclusive to a particular fuse or use )

Here are items on fuse 11, which is 8 amp:

Fuse 11 outputs to Two black wires that leave the fusebox at B8.

One of those black wires from B8 feeds full power to the illumination of the headlight switch.

The other black wire from B8 goes to the potentiometer --- and part splits-off before passing through the potentiometer as a black wire with full power to drive the lights in the heater control and the A/C switch.

The part of the voltage that enters the Potentiometer --- black in, black/blue out.... leaves as a controllable voltage to 3 instrument illumination lights (via trace R12)
and also branches off as a black / blue wire for use by the clock illumination light in the center console



Now, grounds are local to the subcircuit being fed.

So fuse 11 sends power to various places as noted, and these accessories ground locally.

So the clock grounds on one of the two ground studs on the firewall above the fuse panel noted as ground point "6" on the diagrams.

The headlight switch illumination grounds at the steering column (ground point "3")

So do the three bulbs illuminating the instrument panel.

Headlight illumination and heater control / A/C button lighting does not vary with potentiometer. I don't see right-off where the ground is connected, but am pretty certain its also one of the grounds on the firewall above the CE panel.

Instrument illumination and clock illumination do vary with potentiometer.



It gets real interesting on cars where the fuses have been jacked-up like yours.

The melting generally occurs with in the harnesses, too, not just on the circuit board.

I've had to remove the insulation from harnesses to separate melted wires out and to patch the collatoral damage --- sometimes intermittent short circuits, sometimes permanent ones.

Can happen behind the panel, tool. Several times I've found the defroster wires melted into other wires of all types on the back of the panel.


The film on the pod is usually damaged from solder breaks or tears due to mishandling. If there is a burn, I think it comes from other root causes.


Pay special attention to the plugs on the CE panel. Any damaged wires or any scorch marks on the plugs (or adjacent to fuses) is very important evidence.



Pay attention to J5 on the CE panel, too. It feeds illumination to the other dash switches, feeds the mileage reset unit, and the lights associated with front and Rear cigarette lighters. The reason I mention it is its use. The cigarette lighters get hot and get a lot of manipulation, plus they have some heavy power coming from a separate circuit that drives their heating elements and its usually powered-up (IIRC) all the time --- and the little rubber wire caps get brittle ---- and the wires are all in close proximity ---- that crap is all ripe for shorting and cross feeding and even burning down the car. The front cigarette lighter in particular, with the tight fit of the removable ashtray, interference of the gear shift lever with removal of it, and the fact that Stereo installers have there "talented" hands in their looking for power to scab or just manipulating the area as they bungle with the stereo head..... all these factors point to needing to check it. The illumination of the gear selector area is another source of problems in the console on some cars, though I didn't see that light mentioned in the diagrams.

Thanks for the great info Landseer and the double post.

I did not remove the CE panel last time, just cleaned all contacts, like you say, there are signs of melting on red wires on the first few lettered connectors at bottom, will check out J5 as well.

There could easily be melting into the ground circuit. Even R12 illumination lead tests circuit complete when i touch the other lead to ground!

4 hours yesterday repairing both clusters, swapping known working tach into the german cluster. I even repainted the tach needle from the orange original tach to match the more fluorescent red of the german cluster. Getting very familiar with these clusters now. : )

Cluster warning lights seem to work since they must be on another circuit.

One thing is the clock does work and illuminates. This is one tough clock.

Pulled my instrument cluster from my '82 Euro.

several of my board connector traces are pealed back?
What is the general solution here?

Does anyone have a diagram of the instrument cluster connections?
I've got a 3 connector version -- not sure what year.

Not sure exact year
http://forums.pelicanparts.com/uploa...1297706367.jpg
http://forums.pelicanparts.com/uploa...1297706389.jpg
http://forums.pelicanparts.com/uploa...1297706427.jpg

thx,

Mike

It looks like yours is burned in exactly the same place as mine. Does your illumination work on the cluster? Yours should be 3 12 pin connectors I believe in teh 82 Euro. The labels on the circuit film have names for what they go to, usually in german, then match it up to your flow diagrams. PM me if you need, or google cannell.co.uk and porsche and you can download there. You may want to start your own thread / post so we can help you there and keep issues separate. We'll catch you on your thread.

started new thread....

I have the same issue after totally refurbing mine. No instrument illumination,no tach and no fuel or temp gauge. All the warning lights,clock and HVAC,dimming function work. I'll be watching for the outcome. Gunar

Here's what I did with mine. Scroll down the pics:

Porsche 928 Forums dot com - View topic - Pics of my First 928 and Current Project

Wow, GBGastowers, I would bet yours has same ground issue. Sounds like my nightmare all over again, lol.

MPDano, that is fantastic work, I will take a good look once home from work!

Why do you think its a ground problem?

My R7 and R11 short to R12. 7 and 11 are brown wires to looped grounds on the printed circuit, and
R12 illumination from pot. As you suggested, I also think wire melt somewhere is joining them. There is a stereo install as well. Splices abound. Many repairs in harness wires are hidden behind shrink tubing.