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If removing relay #4 will remove the +12v on fuse C7 fused side, then relay #4 is leaking +12v into the circuit.
I will try undoing my fix this weekend and see what happens with that. Another data point - with relay #4 removed, the fog lights and rear driving lights no longer work. Reinstalling #4 restores them, which I think would tend to confirm your theory about #4 being shorted!
The simplest is to undo your fix then remove relay #4, if the temp sensor fan stops and everything else (i.e., lights, heated seats, etc) works and the ONLY side effect is no rear defroster and heated mirrors, then it's very likely you have a bad relay #4 (which has electronics inside to implement the latching function of the defroster switch).
The simplest is to undo your fix then remove relay #4, if the temp sensor fan stops and everything else (i.e., lights, heated seats, etc) works and the ONLY side effect is no rear defroster and heated mirrors, then it's very likely you have a bad relay #4 (which has electronics inside to implement the latching function of the defroster switch).
My friend, you're a genius! I couldn't wait to find out what would happen so after dinner I ran out to the garage and undid my jumper and reconnected the original wire with relay #4 removed. Absolutely everything works as it should...the cabin temp fan runs only with the key on, the seat heaters only work with the key on, and the front and rear fogs work correctly. Parasitic draw shows 25 milliamps.
I owe you a beer! What a circuitous route to take to find a bad relay!
It gets weirder. I googled the number of the relay I pulled out of position 4 (99661511901) and found it referred to as a "Trunk entrapment" relay. It was installed in the defrost relay location. The number I found for a correct defrost relay was 99661511700, which just happened to be the part number of the relay in position 5! I further looked at some photos online and every photo I saw showed 99661511700 in position 4 and 99661511901 in position 5! I took a chance and moved 99661511700 to position 4 and whaddya know, my defroster turns on now. I left 99661511901 at home so position 5 is now empty. So...
1. Can anyone verify that 99661511700 belongs in position 4 and 99661511901 belongs in position 5?
2. What exactly is the "trunk entrapment" relay supposed to do? I cannot find anything that does not work with relay 5 removed, including the remote trunk release on the key.
I guess some ham-fisted mechanic must have inadvertently swapped relay 4 and 5 causing all of this.
OK, here's the full scoop. A "trunk entrapment" relay is exactly what it sounds like. In about 2002, federal law mandated a release handle in the trunk for safety reasons. This relay controls it. So although the yellow handle is literally inches from the latch and one would assume a simple cable would do the job, Porsche knew better and created this electronic apparatus to release the trunk latch. I confirmed this by checking the handle operation with the relay both installed and removed.
So yes, relay 99661511700 (defrost) belongs in position 4 and 99661511901 (trunk entrapment) belongs in position 5. Since the law went into effect in around 2002, that's why earlier cars (and the wiring diagram) show position 5 as empty. I lay the blame for my problem on 2 factors - the mechanic who put the relays in the wrong place and Porsche for putting two totally incompatible relays with identical pinouts right next to each other. Frankly I'm surprised I didn't find more examples of this happening! Do not switch these relays! Bad things happen. On the positive side, everything is 100% fixed and it didn't cost me anything. So there's that.
01-02-2019, 08:38 PM
