German Relay Pin Numbering

[ctaylor738]

All -

I was talking to my friend Dave, who is now the shop supervisor at Porsche of Arlington, and a long-time Porsche tech. I was describing my efforts to get the idle control system on the 380SL to work, and my suspicion that the OVP relay was bad.

So he said, "Just bridge 30 to 87 to test it." So I looked on the wiring diagram, and sure enough, that would bridge the battery voltage to the output to the idle controller.

Dave then explained that those numbers on the relays are actually standard. Here is my recollection of what he said, and after looking at the wiring diagram.

30 - Battery (hot at all times)
15 - Hot with key on (KOEO)
85/31 - Ground
86 - Hot in run or start (or run only?)
87 - Output

Maybe everyone except me knows this, but it was an eye-opener for me.

[cth350]

Those numbers are indeed stamped on the top of the relays for a somewhat grand uniformity.

The 87a contact is the reverse of 87 BTW. Also, I have a cute little red relay from a parts car, who's schematic stamped on the can shows pins 15, 30, 31 and 31a. I presume in this context, the 31/31a isn't "ground", but "return" used to energize other relays. To prove that, I'd have to remember what car this thing came off of and look it up in correct electrical troubleshooting guide.

-CTH

[ctaylor738]

Well, it didn't take long for the secret code to come unglued.

I think you are looking at an OVP relay, similar to the suspect in the 380SL. My cute little red one has 31, 31a, 30a, 30 stamped on it.

From the ETM:

30 - always hot
30a - power out to lambda and idle control
31a - ?
31 - ground

But on the emissions control diagram, they are labeled


30 - hot
31 - ground
15 - to or from "e" not otherwise identified
87 - out to lambda and idle control

[j9fd3s]

even the newer ones are numbered, they have a little diagram cast into the side too which is nice