Power Window/Power Seat Circuits Crossed?

[Smoove1010]

Starting a new thread since the issue in my 87 Cabriolet is no longer a battery-drain as described here: Battery Drain in 87 Cabriolet (Or Not?), it's determining why the power seat circuit (fuse 2 on block 3) is energizing my power window circuit (fuse 1 on block 3.)

With both fuses in, the power windows work all the time, even when fuse 1 and the power window relay are removed! Oddly, this condition is also causing the PW relay to stay energized at all times, resulting in a 90mA drain.

When just fuse 2 is removed, the windows work as described in the manual, i.e., they work with the key on, and when the key is removed until a door is opened. When the car is parked the drain drops to an acceptable 10mA.

As noted in the other thread, Fuse 2 is for the "seat adjusters" and "booster fan" according to the fuse panel label. I noted on the "Seats" schematic 970-44 that both the red/blu and red (always hot) wires have close proximity, though it appears that the red/blu is for the seat heater circuit, and my car doesn't have them. Also noted two symbols on the schematic labeled "J/C (Blue Tape)" and "J/C (Red Tape)" - what are they and where are they? Also on the drawing, below J/C (Blue Tape) there appears to be a connection between the red/blu wire and a red one - am I reading that right, and if so, where might I find that?

It's clear that my car's wiring has been at least slightly molested (there are a number of wires-to-nowhere and a couple of unrelated splices in the frunk) but there a no obvious signs that either of these circuits have been messed with.

One clue - the driver's side seat adjuster has a button missing, and I'm inclined to disconnect it to see if damage to the switch is crossing the circuits. It looks like the seat has to be removed or at least unbolted and raised to get at the connections underneath. If that doesn't do it, the next step is to see how the seat wires are routed to look for crush or cross-points.

Any wisdom or suggestions would be most appreciated.

Thanks,
GK

[cabmandone]

Sent you a PM. If my offer will help, PM back your email address and I'll reply back with the diagrams.

[Smoove1010]

When I wasn't prepping for blizzard Juno today, I took a few minutes to follow steely's advice from the old thread:
- Lifted the driver's seat (there's a fun job...) and located the seat adjuster switch plug and pulled it; disconnected the seat-belt switch harness (just because I could); figured out how to disconnect the passenger seat adjuster control plug without lifting the seat and did so. No joy. This was a long-shot as the Bentley schematic 970-44 shows the red/blu wire feeding the seat heaters (which I don't have) and not the seat adjusters.

- Still following steely's advice, I disconnected the red wire and the red/blue wire from fuses 2 and 1 respectively. There's no continuity between the screws on the fuse block, which is good, but indeed there are 0 ohms between the red and the red/blu wires, which is bad, and the essence of my problem.

Next step: follow the black fabric tape-wrapped wire harness from behind the fuse block as it snakes its way under the fuel filler toward the dashboard. I'll be looking for signs of splicing or pinching. I'll also be looking for the "J/C" objects noted on the schematics.

My windshield wipers won't park, so I might be taking out the ductwork and blower to access the wiper relay and get a good visual on the black-snake-harness while I'm at it.

Additional thought: My fuel pump runs continuously when the key is on even when the car isn't started. I believe that it's supposed to only run for a short period before shutting off if the car hasn't started. I'm wondering if this is a related issue or just a coincidence.

I'm wondering if I need to pay extra attention to this mess of wires just below the fuse panel, under the fuel fuller pipe:

If anyone sees a smoking gun here, let me know!

thanks,
GK

[steely]

Originally Posted by Smoove1010

Additional thought: My fuel pump runs continuously when the key is on even when the car isn't started. I believe that it's supposed to only run for a short period before shutting off if the car hasn't started. I'm wondering if this is a related issue or just a coincidence.

thanks,
GK

Hi GK, nah, you shouldn't hear the pump, and I wonder too if it is related.

When you start the car, the DME gets powered and tells the DME relay to furnish power to the pump by using power from the IGN. If the car doesn't start, and you let go of the key, the relay relaxes/de-energizes and relay killing FP power. If the car starts, the DME looks for good speed/reference signals and uses this logic (that the car is actually running) to keep the FP relay closed/energized (in lieu of the IGN power). I can dig out the real operational concept if you want.

I only see 2 items of interest in the pic - one a missing screw on a fuze terminal and the other a potentially exposed wire circled below.

I will try to look at my schematic based on the new info (no heaters, a persistent fault with the seat unplugged, and a semi-hot wired FP).

[cabmandone]

I checked my diagram and my fuse block for my car and the one Dan circled with the missing screw is your fuel pump fuse. The wire coming in the top should be the wire from the main harness IIRC. I had that particular wire pointed to when I removed the harness from my car a long time ago.

On my 85, the wire from the harness to the top of fuse 3 (missing lower screw) is red/green. It appears to be solid red coming in the bottom where the screw belongs. Let me know if I can take any pictures of my fuse block that might help you sort this out.

Any chance you could post a pic of your fuse block showing the top wires in?

[rick-l]

Do you or did you have a power top? I think it ties in to that circuit also.

[86 911 Targa]

Originally Posted by Smoove1010

Starting a new thread since the issue in my 87 Cabriolet is no longer a battery-drain as described here: Battery Drain in 87 Cabriolet (Or Not?), it's determining why the power seat circuit (fuse 2 on block 3) is energizing my power window circuit (fuse 1 on block 3.)

With both fuses in, the power windows work all the time, even when fuse 1 and the power window relay are removed! Oddly, this condition is also causing the PW relay to stay energized at all times, resulting in a 90mA drain.

When just fuse 2 is removed, the windows work as described in the manual, i.e., they work with the key on, and when the key is removed until a door is opened. When the car is parked the drain drops to an acceptable 10mA.

As noted in the other thread, Fuse 2 is for the "seat adjusters" and "booster fan" according to the fuse panel label. I noted on the "Seats" schematic 970-44 that both the red/blu and red (always hot) wires have close proximity, though it appears that the red/blu is for the seat heater circuit, and my car doesn't have them. Also noted two symbols on the schematic labeled "J/C (Blue Tape)" and "J/C (Red Tape)" - what are they and where are they? Also on the drawing, below J/C (Blue Tape) there appears to be a connection between the red/blu wire and a red one - am I reading that right, and if so, where might I find that?

It's clear that my car's wiring has been at least slightly molested (there are a number of wires-to-nowhere and a couple of unrelated splices in the frunk) but there a no obvious signs that either of these circuits have been messed with.

One clue - the driver's side seat adjuster has a button missing, and I'm inclined to disconnect it to see if damage to the switch is crossing the circuits. It looks like the seat has to be removed or at least unbolted and raised to get at the connections underneath. If that doesn't do it, the next step is to see how the seat wires are routed to look for crush or cross-points.

Any wisdom or suggestions would be most appreciated.

Thanks,
GK

Hope this helps:






^^^^^
You will need to print/cut/paste.

Good luck,

Gerry

[Smoove1010]

Originally Posted by 86 911 Targa

Hope this helps:

You will need to print/cut/paste.

Good luck,

Gerry

Thank you kindly for this. I'm focusing on this part of the middle diagram:

Can you provide some insight into what the abbreviations on the right side mean, and what is meant by "welding point?" I'm guessing that this may help me find the physical locations of these wires and junctions.

I'm also noting that I have a fuse and wires attached to fuse 3 in block 3, which the diagrams say are for headlight cleaners and the power convertible top, neither of which are on my car.

Thanks again,
GK

[steely]

The welding point is a distribution point for power. They are designated with Roman Numerals. I do not know if they are a hard point somewhere (like they are for the ground points), or if they are simply a grouping of splices. So for Fuse 1, welding point XII may consist of 3 wires (as an example and I may not be accurate), one from the fuse, one to the Sun Roof, and another to the Seat heaters.

In the string of abbreviations, the first is the wire diameter in mm^2, the color using German abbreviations (RT/BL for Red/Blue), next the NR or number of the branch (2/60 is a big one), then the welding point, then a reference/flag pointer to the schematic sheet where the welding point can be seen. All of the sheets have an alpha numeric grid system with letters running horizontally, and numbers vertically. I can't make the characters out for the Fuse 1 example. If for example it said G20, you'd go to the schematic sheet with G20 on it.

It's a neat system, and a lot of mechanical assy dwgs in the US use the same method, only we call them zones instead of grids.

I found somewhere that the earlier german schematics referred to the ground points as "masse punkt', so you might see some gnd points referred to as "MP".

I therefore wonder is Welding Point was a literal translation for something else that I would consider a junction or 'butt splice'. I can't find anything about it on the interwebz about as I try to teach myself.

[steely]

The weather (juno) is keeping me a little busy too - but so far it hasn't turned out to be half as bad as they said it would be near Phila where I live. But there is always tomorrow.

That said, I didn't get to far in looking at the dwgs, but I did find a diode that I wondered about.
I hate to have you needlessly perform tests, but if you get a chance, can you re-perform the resistance measurement you made yesterday on Fuse 1 to 2 on block 3 - with the fuses out and on the load side (bottom)?

But do it twice to see if there is a diode between them by flipping the leads.
This is a complete guess on my part, so you don't have to try this before I or someone else confirms.

It may not prove anything if I am wrong.
You would do + lead to F2 and (-) to F 1, read, then flip the leads (-) to F2 and + to F1.
If you get a short in both directions, there is no diode there or if there is, it shorted (got old).
If you get diode action, or a short in one direction and an near open in the other direction, you'll still have to hunt some more. (that would show a diode there , and it wasn't the cause of this problem).

BY the way - if Gerry is looking at this, so much the better!

I am hoping that in the meantime I can confirm if the diode is supposed to be there or not.

[Smoove1010]

Originally Posted by steely

I did find a diode that I wondered about.
I hate to have you needlessly perform tests, but if you get a chance, can you re-perform the resistance measurement you made yesterday on Fuse 1 to 2 on block 3 - with the fuses out and on the load side (bottom)?

But do it twice to see if there is a diode between them by flipping the leads.
This is a complete guess on my part, so you don't have to try this before I or someone else confirms. If you get a short in both directions, there is no diode there or if there is, it shorted (got old).
If you get diode action, or a short in one direction and an near open in the other direction, you'll still have to hunt some more. (that would show a diode there , and it wasn't the cause of this problem).
I am hoping that in the meantime I can confirm if the diode is supposed to be there or not.

Gerry, Dan, Cabmando, Rick - Thanks for taking the time to help me solve this puzzle. I love these little missions, I always end up learning a lot.

Dan - I did the test you asked, and there's effectively no resistance between the wires on the load side of fuse 1 and fuse 2 on block 3, regardless of which test lead is connected to which terminal.

Rick - No, I don't have a power top, seat heaters, or headlight washers. Part of the puzzle here is that there's a fuse 3 in block three which is supposed to be for the top and headlight washer.

Originally Posted by steely

Hi GK, nah, you shouldn't hear the pump, and I wonder too if it is related.

When you start the car, the DME gets powered and tells the DME relay to furnish power to the pump by using power from the IGN. If the car doesn't start, and you let go of the key, the relay relaxes/de-energizes and relay killing FP power. If the car starts, the DME looks for good speed/reference signals and uses this logic (that the car is actually running) to keep the FP relay closed/energized (in lieu of the IGN power). I can dig out the real operational concept if you want.

I only see 2 items of interest in the pic - one a missing screw on a fuze terminal and the other a potentially exposed wire circled below.

I will try to look at my schematic based on the new info (no heaters, a persistent fault with the seat unplugged, and a semi-hot wired FP).

As Cabmando noted, the fuse with the missing screw is supposed to be for the fuel pump as shown on the fuse panel label. There's a taped-off red wire just underneath it, perhaps the original fuel pump lead? With the battery connected and key turned on, there's no voltage at the power side of this fuse (fed by a red wire w/green stripe). The DME was replaced by the PO (and looks new) and the DME relay was replaced by me. Perhaps another wiring snafu that caused a PO to hot-wire the fuel pump, or does the DME or DME relay need the resistance of the FP to activate?

The item circled at the bottom is not an exposed wire, it's a red wire that appears to emerge from the black-fabric-snake wire harness, and what you see there is a splice to a red wire with a yellow stripe, which snakes its way behind the fuse blocks and is attached on the power-side between fuses 8 and 9. Thinking this might have been the tap for the fuel-pump hot-wire, I disconnected it, but with the key turned on, I could still hear the FP running.

Cabmando: You had asked for better pics of the top of the fuse blocks - here are a couple, hopefully these will suffice - if not, I'll snap some more! Here's the left side (fuses 1,2,3 are pulled) and you can see the taped-off red wire below and to the right of the missing screw. You can also see the red wire w/yellow stripe tap described above:

Here's the right side:


I'm hoping to have some time in the AM to chase that wire harness up toward the dashboard, at least until Juno finishes dumping on us, and then my day's work will be cut out for me...

Thanks again brother Pelicans!
GK

[steely]

Thanks for doing that resistance test again.
I looked at the schematic for an obvious cause of the sneak path from F2 to F1, and can't figure any out - other than the possibility that a PO in inadvertently swapped a wire between the red and blue tape.
On the schematics they are drawn as jumpers/connectors with 4 M/F pins/jacks, but I don't know the location.

A portion of the schematics or work shop manual that I do not have unfortunately is the chart that shows the 3-space xyz location of devices and harness connectors.

Power leaves F1 for the windows, the sun roof you don't have, and the seat heaters you don't have either - these are all common to the mysterious blue tape connector.
The power from F2 feeds the A/C, the footwell blowers, and the seat adjustment -and is common to the Red tape connector.

With the short on the load side between F2 and F1, the F2 power would furnish power to the windows, completely bypassing the window control relay, and in fact, leaving it on (when it is plugged in). You found this, but I wanted to confirm for myself from the schematics as a possible mode.

So, we're back to where we started - a possible short between the F1 and F2 in the harness or just maybe someone jumpered the red and blue taped connectors. Another chance is that the short could be inside the 8-pin seat connector on the harness side. If the seat adj power touches the seat heater ckt insde of the backshell of the connector -badabing.
Porsche wired the harnesses near completely, even if you didn't get the heater option in the seat.

For the fuel pump, the disconnected / taped red wire used to go directly to the pump from the bottom of fuse F3. I wonder if the other end was dead-ended at the FP?

The Red/Green wire should come from the DME relay to the top of F3, and this is what you found. It will be dead with the key ON. It will only go Hot when starting or running.

Can we say that when you measured this Red/Grn wire with the Key ON and found it dead - was the fuel pump running? Can you check it with the car running? That might show that the DME FP control is still working albeit unused.

sorry if I am repeating myself or if you already answered this above.

BTW - I mentioned earlier that the welding points are for power distribution, it looks like they can be used for GND distribution as well.

good luck in the snow tomorrow - I hope it isn't as bad as they're calling for.

[Smoove1010]

Originally Posted by steely

Thanks for doing that resistance test again.
I looked at the schematic for an obvious cause of the sneak path from F2 to F1, and can't figure any out - other than the possibility that a PO in inadvertently swapped a wire between the red and blue tape.
On the schematics they are drawn as jumpers/connectors with 4 M/F pins/jacks, but I don't know the location.

A portion of the schematics or work shop manual that I do not have unfortunately is the chart that shows the 3-space xyz location of devices and harness connectors.

Power leaves F1 for the windows, the sun roof you don't have, and the seat heaters you don't have either - these are all common to the mysterious blue tape connector.
The power from F2 feeds the A/C, the footwell blowers, and the seat adjustment -and is common to the Red tape connector.

With the short on the load side between F2 and F1, the F2 power would furnish power to the windows, completely bypassing the window control relay, and in fact, leaving it on (when it is plugged in). You found this, but I wanted to confirm for myself from the schematics as a possible mode.

So, we're back to where we started - a possible short between the F1 and F2 in the harness or just maybe someone jumpered the red and blue taped connectors. Another chance is that the short could be inside the 8-pin seat connector on the harness side. If the seat adj power touches the seat heater ckt insde of the backshell of the connector -badabing.
Porsche wired the harnesses near completely, even if you didn't get the heater option in the seat.

For the fuel pump, the disconnected / taped red wire used to go directly to the pump from the bottom of fuse F3. I wonder if the other end was dead-ended at the FP?

The Red/Green wire should come from the DME relay to the top of F3, and this is what you found. It will be dead with the key ON. It will only go Hot when starting or running.

Can we say that when you measured this Red/Grn wire with the Key ON and found it dead - was the fuel pump running? Can you check it with the car running? That might show that the DME FP control is still working albeit unused.

sorry if I am repeating myself or if you already answered this above.

BTW - I mentioned earlier that the welding points are for power distribution, it looks like they can be used for GND distribution as well.

good luck in the snow tomorrow - I hope it isn't as bad as they're calling for.

Dan -
Thanks for thinking this through, and for being so methodical in your approach. Indeed I did not test the red/grn wire on fuse 6 with the motor running, but will do so. It makes sense that the car would have to be running for the DME to provide power on that lead. At some point I'll have to get under the car to see if there's another dangling wire near the FP, or search for a jumper somewhere upstream. It would seem like a common hack to bypass the DME relay permanently in this way, but I'd rather restore this to the way it was intended to run (and carry a spare DME relay...)

I'll check the innards of those 8-pin connectors at the seats for a possible short there as well. The seats on this car have been out before, so you never know who mucked with what. I also want to chase the wires from those connectors up toward the firewall to see if there are any pinch-points or obvious hacks.

While I'm getting up-close-and-personal with my car's wiring, I find it disconcerting that there are so many loose connectors/wires-to-nowhere up front. Could they all be for the headlight washers and high-intensity window washers that I don't have? Also - the black wire on the power side of fuse 1 seems to be rather small in size considering it provides power to a 25a fuse, and the red/blu wire on the load side is easily twice as thick.

Luckily Juno dumped about 10 fewer inches on us than expected, but I've still got 8" of powdery snow blowing around out there to clear. At least we avoided The Big One!

Thanks again, I'll be reporting back on progress and/or other clues.
GK

[cabmandone]

Could there have been a jumper created at the DME relay to power the fuel pump when the key comes on? It would be interesting to know what fuse kills power to the fuel pump since it can't be the one that was designed to do it.

[86 911 Targa]

^^^^^
With the exception of the fog lights (grey/red-spice) wire modification,
here is the correct stock fuse panel wiring.

G.

[cabmandone]

Originally Posted by 86 911 Targa

^^^^^
With the exception of the fog lights (grey/red-spice) wire modification,
here is the correct stock fuse panel wiring.

G.

That's strange, your fuel pump fuse (6th from the left) appears to have two wires on the bottom side. My 85 does not.

[steely]

GK - glad about the snow reprieve - we got 3or 4 inches, instead of 8.
The F1 wiring gage difference is correct, although I don't know why the size difference either. The snippet of Gerry's schematic in your post #8 shows 2.5 mm^2 SW (Schwartz) in, and the larger 4.0 mm Red/Blue. That, and the pic from Gerry show yours to be stock.
Maybe rick, Gerry, Cabmando know - perhaps it is larger to permit splicing downstream (more physical wiring technique than a current handling question?).

I too have found some orphan wires in my care, but they are usually terminated to unused connectors). Although I haven't had a need to search for them, so maybe I have more and don't know it. I also don't think my wiring was changed, especially around the fuse boxes. Sorry I can't respond with a class-1 answer on the washer wiring. Do you know if you had this stuff once and it was removed?

[scarceller]

Originally Posted by cabmando

That's strange, your fuel pump fuse (6th from the left) appears to have two wires on the bottom side. My 85 does not.

Bingo! the fuel pump fuse should only have 1 wire on each end.
The fuel pump should only run while cranking 'START' and then the DME keeps it activated once the engine catches.

Investigate the mystery wire on the fuel pump fuse, most likely it's back feeding the pump. Also unplug the DME relay, does the pump still run? it should never ever run with the DME relay unplugged as it's not possible in the stock wiring configuration.

Do those tests and we go from there

[steely]

Originally Posted by cabmando

Could there have been a jumper created at the DME relay to power the fuel pump when the key comes on? It would be interesting to know what fuse kills power to the fuel pump since it can't be the one that was designed to do it.

+1

I'll have to look at this to refresh my thin memory to see how the DME gets power.
If the PO didn't rob power at the fuse box somewhere, the DME would be a next choice since it's so close to the relay. There was a neat article on the DME logic (diode or'ing) to the DME replay I found once on dorkiphus.net that explained it.

[SpyderMike]

By the way, if you didn't know, the clear-ish plastic housing behind the lower red circle in your pictures is a J-Connector - a FASTON connection grouping. The Weld Points are more like crimp type butt splice groupings covered with a plastic or heat shrink protector (example in my photo to the right of the green vertical tape). Here is a sample showing the main Red/Blue feed going to the Weld Group and the J-Connector. This is from my 1985.



That Dorkiphus thread regarding DME is a great resource:

http://dorkiphus.net/porsche/showthread.php?t=16859

Regarding your comment about the relative sizes of the black wire on top of fuse 3-1 and the much larger red/blue wire on the bottom of the fuse, I can only comment that we don't get off easy with this car wiring scheme. That large blue/red wire (on my car anyway) goes only a few inches before it branches over to a few other (see my photo).

It probably started out straight forward wiring scheme on the very early cars. By the time ours were made, there is now a convoluted scheme that morphed over time as new systems were continuously added. I got tired of trying to sort it out and pulled the fuse block completely. I am stripping the car back to basics and rewiring mine using buses and straight forward fusing and relays (once circuit per fuse type of approach that does not use the ignition switch and or any other switch for major power distribution). I have been scratching my small brain about this for months and am finally getting it together. I couldn't stand back and understand the overall scheme - it is too complex. I had to take it circuit by circuit and understand each circuit as a stand alone.