jpitman2

I would look seriously for a new fuse panel, as it will be a big job to clean all the relay contacts there. Looks like it has had water leakage onto the panel. Relays marked '53' are generic, so anything can go there. Important one to get right is the fuel pump, which has an extra pin for sensing sparking, and a start-up prime. If you try to repair this one, get the right tools for releasing the female sockets from the panel - cheap on ebay, just have to find them.
https://www.ebay.com/itm/18x-Car-Wir...-/273498864492

jp 83 Euro S AT 57k

Hey_Allen

Amazingly enough, the fuel pump relay is one of the few that is functional, once I got the fuse to make contact.
I had that working, but nothing much else, before I pulled the CE panel and found this mess.

Like Karl was suggesting, I am trying to get the car running before sinking a lot of money into making everything I find "right".
This car was rescued from being scrapped, as I wanted a project, and the 928 is the only Porsche body that has ever really caught my eye.
That said, I'm only into the car for a couple hundred dollars at present, and I don't want to invest significant amounts of money into it, only to eventually find that there is something completely destroyed, making it a wasted effort.

I don't mind projects, but I don't care for outright wasted time, effort, and expense.

I do have a 25mL bottle of DeoxIT D100, and will have plenty of time this winter, so will probably go ahead and tear the panel apart terminal by terminal, making sure that the contacts are at least passably clean and intact.


I am finding that many of the relays don't seem to match up to anything for a 928, and some that have 928 part numbers still don't seem to match up to anything.

One example: in the XI position (AC Compressor), there was a relay with part number: 928 615 103 01
This "relay" broke when I was extracting it, and turned out to only have a pair of diodes inside.
I can't find that part number anywhere online, nor does it match the current flow diagram, or the CE Panel diagram that is annotated with the supposedly correct ratings and parts for early body cars.
From what I can see online, the AC Compressor relay should be one similar to the fuel pump relay, but with a higher tach speed detection threshold, not a pair of diodes...
I'm not particularly worried on this relay, since the AC condenser is missing, and the system is empty, but there were numerous goofy mixed up relays on the panel.

jpitman2

Here is how you can pull terminals out of relay sockets:
1. Steel blade 2.5mm wide (3/32") - curiously I find such things fall off the brushes used by street sweeper machines. Round the end a tiny bit with a file.
2. Narrow steel blade out of the set of tools linked to above.

3. Push the wide blade in the little slot next to one of the 1/4" sockets; push the socket IN from the back to unload the retaining tag; Push the steel blade HARD - I tapped mine with pliers, and simultaneously pulled on the wire from the rear - out she came.

4. Similarly with the narrow blade on the small sockets (1/8") where present (fuel pump etc).
Result - note the retaining blade at an angle.

They are a real PITA to get back in - need to be straigt and correctly aligned. Surprised to hear of a specal on the A/C. The number sounds like the fuel pump relay, which needs to detect ignition pulses to keep running after its short prime run is over. Are you sure you have a correct map for the relays and fuses? I have seen maps for my 83 showing pump at fuse 13, but its at 22 in reality.
All my spare board relay sockets have sockets for 2 small pins, 2 of them have 4 such sockets, but its hard to see how many are occupied.
jp 83 Euro S AT 57k
j

Hey_Allen

I was using the attached drawing for the relay numbers, but it could be wrong.

Here's a link to the spreadsheet I put together, trying to keep track of what I found where, and what appears to belong in each position.
https://drive.google.com/open?id=10h...H_3cnHKSPKHY18

karl ruiter

Not important right now the the AC relay is called the 'AC speed control relay' or something on the wiring charts. I think its job is the shut off the compressor during starting. On my '79 I have a jumper on it, and that seems to be OK for now.

Hey_Allen

In the interest of keeping it cheap and getting it running again, I started with checking the wiring on the CE panel.
I was somewhat amazed to find that despite the discoloration on the plastic from the rusty relay blades, the copper(?) contacts inside appear to have nothing beyond a little oxidation on most, and the worst was a bare hint of some verdigris on the crimp of a couple.

Now, the relays were in fairly rough shape, and while I was able to get a few cleaned up, it looks like I'll have to source a few replacement parts.
Luckily, most of the broken relays are the generic ones with no smarts, but a couple were fancier, and will require eventual replacement if I want their functions to work properly.

Thank you, JP, for the tip about the street sweeper blades!
I had to rummage a little bit to find the stash of them that I've found over the years, but one already had a bend in one end that made a great handle, and I was able to use it to pop the terminals out with relative ease.


I do have to ask, is there some strange magic to the Porsche or VW group multi-purpose relays that makes them different than the other Bosch 4 or 5 pin relays with the same pin arrangement? I was shocked when I looked up the part number and saw that the Porsche part was listed for ~$120, and the OEM non-Porsche parts were listed for various prices, from $10-60, depending on what application they were listed for, even with the same part number interchange...

jpitman2

For the fuel pump relay Roger does the correct unit (spark sensing, short priming run) around $20 last time I bought one. Obviously the double headlight relay is unique, so no options there. Dont remember which others are special. There is a VW wiper relay that is programmable (pause wipes) that is cheap.
jp 83 Euro S AT 57k

Hey_Allen

I'll have to look into the VW relay if and when I get that far, but luckily the fuel pump relay works, and the other relays appear to be unnecessary for basic engine start and run functional testing.

Hey_Allen

Well, I went ahead and reinstalled the CE panel, after cleaning the two ground points on the brackets that it is secured to.
After testing to see if there was any difference in the fuel pump or cranking behavior after all this work, and found that the pop-up headlights appear to be possessed now.

If the ignition is off, the headlights now crank up and down, no matter what position the headlight switch is in.
If the ignition is on, and the switch is off, the lights will go stop, at any position, not just fully up or down...

Unrelated to this, I noticed that fuses 4, 6, 13, 25, 27, 31, and 33 all appear to have nothing connected to the second terminal, unless there is a connection other than the spade terminals on the rear of the panel.
I'm trying to figure out just what they might be intended to be connected to, as the 78 and 79 schematics are not quite identical, but the 79 schematics have wiring color codes, as opposed to the 78 one that I have, which has no color information. The original manual might have had color, as opposed to just color labels, but I don't have the original book version.

Wisconsin Joe

There are internal connections in the fuse blocks. What appears to be "unconnected" fuse holders actually have bars that are hidden connecting them.

That is one reason why switching the fuse blocks between panels is something that must be done with great care.

Also, many of the relays are simply Bosch "53" type relays.

Roger at 928s R Us has them at a very reasonable cost. He also stocks the 'oddball' ones, and although they won't be as cheap, he charges as low or lower than anyone else that I would trust.

Yes, you can find really good deals on "Genuine Porsche Parts" on E-Bay.
But do you know and trust the seller?
Do you know for certain that you aren't getting cheap knockoffs?

And, FWIW, Roger charges less for genuine Bosch relays than some of the E-bay sellers charge for the knockoffs.

Hey_Allen

I gave up for the night and unhooked the negative terminal to get the headlights to quit cycling up and down last night. I left the battery maintainer to top up the charge while took a break to dig through the forum for any likely leads on why they were doing it.

Regarding the relays and the headlight motor, the relay that supposedly controls them did not stop the cycling, even when it was completely pulled from the panel. I even pulled the fuse that I thought provided power to that motor, and it kept running, so I'm going to be doing some digging to see what extra wiring may or may not be up there, or what I may have cross-connected when I was reinstalling the panel.
I did plug in the cables letter by letter, but who knows...

karl ruiter

Last I bought, Roger had the general purpose TYPE 53 relays for stupid cheap. I don't remember the price, but I did not hesitate to just replace them all.

checkmate1996

If it were me, I'd pull the engine given how dirty and most likely corroded. Save yourself sometime...it'll payoff in the end.

Hey_Allen

How and why would corrosion in the interior electrical wiring pay off in pulling the entire engine, from a car that is from all accounts here, a royal pain in the rear to pull the engine on?
I'll be the first to say that it's not a show room car, but that seems like taking the "while you're in there" principle a lot far, not just a bit.

I'm more than willing to accept input and suggestions, but I'm missing something here, where the logic leads to pulling the engine as I seem to so often see suggested?

Hey_Allen

On the electrical troubleshooting side of things, does anyone know what car this relay is supposed to be from?
P/N: 928.615.103.01
I don't see any in the schematic showing three diodes inside a relay package, but I found this in my CE panel, and am wondering just how many cars may have "donated" parts courtesy of inexperienced owners or maintainers in the past.

I found it in the XI position on the CE panel, which should be the AC Compressor relay, from the 77-79 CE panel drawing I was working off of.
The 78 schematic doesn't label the relays by location like the later ones do, but even going by the relay schematic symbols, there are some that have a diode or two in the package with the relay, but none that are only filled with diodes in a relay housing.
Looking on the application specific search on one of the vendor's sites, it looks like there should be a 928.615.117.00 relay there instead, which I found one of in the X position.