Here's the DME relay power schematic.
http://forums.pelicanparts.com/uploa...1422393103.jpg

http://forums.pelicanparts.com/uploa...1422393117.jpg

Thanks Gerry. I may come back to you and ask for a little clarification or confirmation as to what colors/stripes are on some of those. Your relay layout and number looks a little different than mine but Bentley indicates that, aside from relays, the 86 and 87 should be identical (barring the "subject to change" disclaimer.)

Thanks again for this.
GK

I'm doing this next. It may not fix my power window relay mystery, but then again, it might!

THX
GK

After I look for a fuse that disables the pump when pulled, I'm doing this. Excellent suggestion, thank you.

GK

Thanks for the explanation about the J-connectors. I was looking at that thing last night and wondering if that's what it was. I'll have to see if I can get better access to it - it's wedged in that spot - and see if the wires are crossed or shorted.

I am by no means a wiring expert, but I agree with you - the wiring in this car has the look and feel of a basic system that's been added-on to time and again. On the up-side, it's all pretty accessible and relatively easy to lay eyes on. I'd never have the big-brass-ones to pull it all out and start over like you did though... There's the temptation to just button it back up and leave as is, but I'm a little too OCD to live with something that's not working as designed, and the fuel pump issue is a safety issue.

Thanks again!
GK

Today I love my snowblower almost as much as my 911...

On that black wire feeding fuse 1, I see what you mean, and I can at least be confident that it's "correct" even if it doesn't look right to my uneducated eye.

I guess if the orphan wires are terminated by a connector, it's just part of the harness that's not used for my lightly-optioned car. If it's taped off, it's a sign of corruption... As far as I know, there were no features that were removed. I believe the front bumper and valance to be un-original, and I wondered if it might have had headlight washers, but there's no headlight washer switch inside. This car has a few little mysteries like that.

Thanks to you gents I've got some good directions to pursue. I'll be reporting further on this mystery once I've gathered more clues...

Thanks again!
GK

[QUOTE=scarceller;8458595]Here's the DME relay power schematic.

http://forums.pelicanparts.com/uploa...1422393103.jpg

Power from the ignition switch comes in on the line to connection 86 and powers the right hand coil in the diagram. It exits through 85 on the brown wire to ground.

This lets unfused power from the Battery + in on the large red wire at relay connection 30. This power flows out connection 87 to the DME, powering it. It also flows though the left hand coil closing that relay. The closing of that side is controlled by the DME through the ground of that coil wire 85b. Once the DME closes that ground and the left coil is energized, the the power in from 30 is now routed to power the fuel pump out connection 87b. It flows to Fuse 3 and then to the pump. If you pull Fuse 3 then your fuel pump should not run. Based on the schematics above, it should be Red/Green wire on the top of Fuse 3 and Red on the bottom.

On my car (late 1985), that large red unfused fuel pump power feed is a ring terminal connection at the battery + terminal. It is encased in black protective tube so that it looks like a black wire. It routes down between the tank and the tub below the fuse block.

So, if the DME relay fails, you can jumper 30 and 87b to bypass the DME relay and get the fuel pump working.

For your fuel pump to work, assuming normal wiring, whenever the key is switched on, both coils would have to close. You either have a jumper in there somewhere, or the ground control wire 85b is hard grounded (or DME module fault causing a hard ground), or someone has moved the wire to the fuel pump that is downstream of the DME relay to switched power location (at the fuse block?). The fact that your first photo showed no wire on the output of Fuse 3 says that maybe someone has moved that wire to a switched hot location. The power for the fuel pump comes in at the top of the fuse block and out through the bottom. I would look for that red wire that is moved to a location of switched power.

If it was me, I would be checking this wire here (in blue):

http://forums.pelicanparts.com/uploa...1422422018.jpg

Is that a red medium gauge wire in electrical tape? That could be the fuel pump wire as well (correct gauge and it could fit at the lower fuse location. If it is, then someone got real creative with your fuel pump wiring.

The other area in green and the fuse to the left of it - there should only be one red feed for the cabriolet top. There are two up there and that is switched hot feed. I would check those next. Pull them one at a time, isolate them, and see if the fuel pump works.

Thanks Mike,
I agree, that taped-off red wire is a red flag, it will be one of my avenues of investigation. I may start at the FP and try to work my way back.

Regarding the leads that you circled in green (fuse 8 on the middle block) the diagrams indicate this:
http://forums.pelicanparts.com/uploa...1422454558.jpg
...and the power top is powered by fuse 3 on block 3. Regardless, There's a big red wire on the power side of fuse 8 that isn't accounted for in the diagram. In addition, I don't have a power top or headlight washers and still my car has connections to fuse 3.

I wouldn't be surprised to find some "creative" solutions in this car - the PO used to take it to one of those national chain tire stores whenever he had issues with it! Lucky for me, I really like solving puzzles.

After spending the day moving snow yesterday I had lost my initiative for wire-chasing, but it could be a busy night in the garage tonight.

Thanks!
GK

Unplug the DME relay and turn key to 'RUN', does the pump run? If so it's not the relay nor the DME.

After looking at your picture of the fuses I see a issue, the 3rd fuse from the left (blue fuse) is the Fuel Pump fuse and it's missing the screw and the wire at the bottom that feeds the pump! Looks like someone moved the FP wire else where! The red wire at the top of that fuse comes from DME Relay pin #87b. That missing wire is your problem!

And the 4th fuse from left with the cut taped wire is for Brake Lights and Cruise Control.

I have a theory (hunch) what may have been done, they may have removed the factory alarm from the car and if this is done the pump will never run when key goes into 'START' and they did not know howto properly fix the issue. So instead they simply moved the FP wire to a fuse that always has power in 'RUN' and 'START'. Was the factory alarm module removed?

As already mentioned, fuse #8 from the left looks odd. I bet that the red wire at the top is the FP feed that was relocated from Fuse #3.

If the alarm module is removed you must jumper these 2 pins as shown in this picture I marked up:
http://forums.pelicanparts.com/uploa...1422459533.jpg

That's an easy test, and I'm adding that to my list of tactics, thanks.


Agreed. The remaining questions are, 1) where is the red wire that feeds the FP? (Probably tapped into the power side of the fuse panel) 2) What were they trying to "fix" when they did this? (and there are many potential answers to that...) As far as the taped wire goes, I think there is already a wire attached to that 4th fuse, but I have to look at it again in person, photos can be deceiving.

The module is in place, but I'll have to look for cut or bypassed wires going to it. It could also have failed, necessitating a bypass.
Thanks for the suggestions, much appreciated!
GK

GK, the FP wire may be one of the red wires sitting at the top of fuse #8 now. My bet is that the pump will run with the relay out, if so then remove the 2 wires from fuse #8 does it stop running?

Kudos to Sal and Mike for spotting the culprit, i.e., the tap on top of fuse 8:
- I disconnected the fuel pump relay and as Sal predicted, the fuel pump ran with the key turned on;
Referencing this pic with Mike's highlighting:

http://forums.pelicanparts.com/uploa...1422422018.jpg

- I removed the red wire on the power side of fuse 11 (fuse 8 on block 1, the pink fuse) and the pump did not run with the key on;
- Followed that red wire down behind the fuse panel and under the filler neck, and found where it is spliced into a harness here:

http://forums.pelicanparts.com/uploa...1422500961.jpg

You can see the red wire that's connected to the fuse panel is spliced to a red wire that leads into a black plastic sheath that leads toward a hole in the frunk floor, apparently headed to the fuel pump. Also in that sheath are two brown wires and a light weight red wire w/ white stripes that's simply cut.
The brown wires in the sheath are spliced to two brown wires that lead to the grounding point on the inner fender near the fuse block.

As far as the taped-off red wire (circled in blue above) I can only trace it to the point at which it enters the black-fabric-wrapped harness immediately behind the fuse block.

Next steps:
- The taped-off red wire still seems like it ought to go to the FP - I think I need to jack the car up and look at the wiring underneath for more clues. The splice job I found might not have been into the original fuel-pump harness;
- I see at least three other points in that maze of wiring near the filler neck where there are other splices, i.e., crimp connectors wrapped in tape. There was clearly some improvising going on here at some point, and it's a bit disconcerting. I may be in for a little more than I counted on...
- I suppose I could take that red wire that I now know is connected to the FP, attach it to the load side of fuse 3 (with the missing screw) and see if the car starts and runs, and if the fuel pump runs only when it's supposed to.
- Back to my original quest to figure out why the power window relay is always energized, I took a close look at this connector which, thanks to SpyderMike, I now know to be a J-Connector:

http://forums.pelicanparts.com/uploa...1422502075.jpg

What's confusing to me is that Bentley schematic 970-44 shows two separate connectors and seems to indicate that the red wires from fuse 2 are isolated from the red/blu wires from fuse 1. In the J-connector in my picture, the red and red/blu wires seem to be all connected together! How could this be correct if the effect is to bypass the power window relay since the power to the red wires is always on?

Thanks again for your help - the quest continues...

GK

Hey, this beats watching TV!

Why someone did what they did is a mystery. Maybe they cut the wrong loom (all of the wires in the loom you show have been cut) and it cascaded from there. Unfortunately I am 1000 miles from my car for a while. It has the wires for each system separated by circuit at this time and it would be easy to help you further.

Check out this photo for future reference if needed:

http://forums.pelicanparts.com/uploa...1422504355.jpg

The wires that go to the DME relay from Batt+ seem to go between the fuel tank and tub then through the smuggler's box. The other wire loom in the photo is going full width side-to-side are the brake warning wires. The wires to the fuel pump from Fuse 3 go down through the hole where all the other aft routing wire looms go (in front of the brake MC Booster).

My notes show a small red/white routing to the bottom of fuse 1-7. It seems like your issues might have to do with the wiring related to that fuse. Take a look at the fuse block diagram up earlier in this thread. The outgoing wires on fuse 1-7 should be red/white.

Let's take it circuit by circuit. Finalize the fuel pump issue and then let's see what else isn't working....just an idea.


Mike

If I get bored painting a ceiling (or maybe I should say "when") I'll go out and pop the frunk and see what I can find for the connectors in that area. Mine is luckily pretty unmolested so I might be able to add some pics for comparison.

Either way it sounds like you're on the right track with the fuel pump mystery.

The wire from the fuel pump '+' MUST go to the bottom of Fuse #3, that's the stock config.

Next test just for fun:
Measure the voltage at top of fuse #3 (it has a red wire at the top) that wire goes back to DME relay 87b. Leave the meter on this wire and then remove the DME relay and jumper pin #30 to 87b at the relay harness (no need to even put key in ignition). Once jumper is in place do you have 12vdc at fuse #3? If so we are good. And we'll move to next steps.

If you wish to really fix the wiring back to stock you MUST locate the solid RED wire that feeds the pump, this was the wire removed from bottom of fuse #3 and I bet it's one of the red ones at the top of fuse #8. Remove one at a time from fuse 8 till you have the RED wire IDed and then put this wire back on fuse #3 and we'll go from that point.

My theory on what was done: Back in the 80s and 90s aftermarket alarms were very popular and often when installing these they mucked with the factory alarm and messed up that alarm module connection to the DME relay. Find the alarm module and look closely to see if they cut into any wires on it, particularly that black wire that goes to the DME relay.

Thanks Cab, I'm especially interested to see if you have the J-connector in a similar place. BTW - I've got a ceiling waiting for my attention as well, tis-the-season for such indoor projects, so naturally I'm out in the garage!
THX
GK

I agree, it DOES beat watching TV except for the part about being warm. Who doesn't like a good mystery though?
Thanks for the pic - sorting out that spaghetti would be so much easier with the gas tank out (and I've been tempted....)
I'm wondering if that thin cut-off red/wht wire is a clue or just a diversion. I suspect that chunks of the existing harness were re-purposed, so that sheath with the two browns, one red, and one red/wht might have been for something else entirely, and was re-jiggered to feed constant power to the FP. The only other thin red/white wires I can find are for the windshield wipers, and they are working (they just don't park or do intermittent.)

Another example of apparent re-purposing: The two browns on the side of that splice that lead to the grounding point are fabric-wrapped with 4 other thin brown wires that were cut:
http://forums.pelicanparts.com/uploa...1422542375.jpg

Which leads me to think that somebody is being deprived of a ground connection, or replacement grounds were improvised, or somebody had chunks of wiring harnesses from other cars laying around... This is like electro-archaeology.

I'm tempted to remove all the electricians tape that I see, and really get to the bottom of this. I know it's probably best to focus on one circuit at a time, but the big picture might help as well.

Thanks for the input! I'm going to keep at it until it's resolved (in the season finale!)
GK

This ^ is an excellent suggestion - this will be my next step. All evidence to this point suggests that the red wire on top of fuse 3 is coming from that relay, but diligence counts. This will prove that continuity without me starting the car.

Getting the wiring back to factory specs in total might be something I do piece by piece - I'll be satisfied to get the FP and power windows powered properly for now. You were right, that red wire at the top of fuse 8 leads to the FP via that splice, but I want to get under the car and prove it without a doubt. I also want to see if the taped-off red wire under fuse 3 might have been the original lead to the FP, if it's possible to determine that. If so, I may put the original one back into operation.

Checking the alarm module will be my 2nd next step. I'm pretty sure it's a factory alarm system, but you never know. As I've been getting intimate with the wiring in my frunk, I'm noticing a lot more black vinyl tape, so even if the wires aren't cut at the module, they might be cut further upstream closer to the fuse panel.

Were there common failure modes of these factory alarms? It woud be terrific to get the alarm system working as designed, though certainly not a necessity for me.

Thanks very much for the insight and the help, it's much appreciated!
GK