308 Frequency Valve Help

These "protection" relays come in both "with fuse" and "without fuse" configurations. You can use the "without fuse" type, but only (safely on a F) if you add a 10A fuse between the wire normally directly connected to terminal 30 and terminal 30. Any added inline fuse in the area?

Even though they function the same, the original '84-'85 US 308QV protection relay has 5 terminals (of which only 4 are used). The 328 protection relay has 4 terminals, and it can be used as a substitute, but only if you move the wires around. Obviously, your system has already been mucked with, but this jpeg describes how to connect the wires in a US 308QV to the US 328 protection relay:
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Hopefully, you should be able to figure things out from the wire colors, but give a shout (and post some photos ) if you need more help. If your "replacement" protection relay had the same terminal numbers as the stock 308QV protection relay, connecting 30-to-86 would cause the fuel pump to run (but that's not what's wanted) -- on the older 308QV protection relay connecting 30-to-30a would be the same as connecting 30-to-87 on the 328 protection relay (but before ever doing this jumper test, you should measure the battery voltage when the engine is running at ~2K RPM -- even if poorly. The function of these protection relays is to protect the ecu from a haywire alternator output).

The available online 308QV parts manuals are for the euro/standard version only (and those, being K-Jet without Lambda, don't have a protection relay).

 

Correct, the older US 308QV 5-terminal protection relay is no longer available -- and I'm (now) having a vague recollection that the (non-user-replaceable) 10A fuse is built inside so it probably is the stock piece that you have (so please ignore the "added fuse" stuff).

Our latest information is that the 92861512400 has been superceded by 92861512402 (and can be had from Porsche part suppliers, although some of the F part suppliers prices aren't terrible), but if you can find a 92861512400 that's fine too:
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I have a question for Steve M.

So, my FV is not working also which I came across this thread where its mentioned about this protection relay and with that said, I purchased a relay tester. My question is... are these large protection relays supposed to "click" when they are tested? Strange thing is, it doesn't click but the tester gave me a green light. Then to see if the tester is working like it should, I also tested the two small relays on K-jet box and they both click, so I know the tester and the 2 relays are functional. Thoughts?

 

Yes, the Protection Relay has a moveable contact armature inside that should "click" when activated, but your problems are:

1. Even though the male spades on the Protection Relay are in the same physical locations and orientations as the little cube Bosch relays (so they both can plug into the same kind of female socket), the terminal functions are not in the same positions, and

2. The Protection Relay has many more electrical components inside so has more electrical "paths"/stuff than the little cube relays (this could "fool" a simple tester).

Here is a picture of the terminal numbers of the Protection Relay -- note that the 30 terminal on the Protection Relay is not in the same place as the 30 terminal on the little cube relays:

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This jpeg describes how the Protection Relay works. If you want to manually bench test it (with fuse in place):

1. Apply ground to terminal 31
2. Apply +12V to terminal 15 (it should "click")
3. Measure the resistance between terminals 30 and 87 = should be 0 Ohms (or just a small value)

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Thanks Steve... Like before, you're always a HUGE help! Thx U

 

I should've added that my comments are for the later 4-pin Protection Relay. I believe your 1985 US 308QV might have originally come with the (now unavailable) 5-pin Protection Relay. -- if so, the testing for that is a little different and the pins/terminals are different (terminal 31 = ground and terminal 86 = +12V should do the "clicking", and connect terminal 30 to terminal 30a) . If you need to replace an older 5-pin with a newer 4-pin, you need to move the wires around in the female socket like this:

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Steve... you mentioned a good point, in which I've should stated in my help text... my Protection Relay it's not original, the previous owner converted to the four pin relay, color coded pig-tails coming off the original five pin base connector... I have a 1985 QV GTS US car