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Swapping combo relay from a 76 530i to a 77 530i ?

Posted: Sun Jul 07, 2019 2:14 pm
by canada karl
Can I do this without an issue. The relays look different,the 76 has the metal casing and the 77 they went to a black plastic case and the part #'s are different but I suppose they should perform the same function? Haven't pulled the wiring connectors out yet on the 77 to see if they match up.

Re: Swapping combo relay from a 76 530i to a 77 530i ?

Posted: Sun Jul 07, 2019 7:02 pm
by Robert Bondi
I think it would work, but that's a guess. I suspect the black plastic case is more an indicator of much more recent manufacturing than a different part and possibly also a part number supercede to explain that difference too. I can tell you my 77 530i originally had a metal case combo relay too. It's worth trying if pin count, size, orientation ,etc.... match.

Also check the obvious like the fuse box and just unplugging and reseating various electrical connectors is often revealing.

Re: Swapping combo relay from a 76 530i to a 77 530i ?

Posted: Sun Jul 07, 2019 11:50 pm
by Mike W.
I thought all 530s were the same. 528s I know are different. But what does Realoem say? It's not perfect, but it's an invaluable resource that's usually right.

Also as Robert said, check pinout by number and location.

Re: Swapping combo relay from a 76 530i to a 77 530i ?

Posted: Sun Jul 14, 2019 1:04 pm
by maybeillbuyit
Robert Bondi wrote:
Sun Jul 07, 2019 7:02 pm
I think it would work, but that's a guess. I suspect the black plastic case is more an indicator of much more recent manufacturing than a different part and possibly also a part number supercede to explain that difference too. I can tell you my 77 530i originally had a metal case combo relay too. It's worth trying if pin count, size, orientation ,etc.... match.

Also check the obvious like the fuse box and just unplugging and reseating various electrical connectors is often revealing.
I agree, my 77 had a metal case. I seem to remember swapping a different part no combo relay into my car at some point. The pins were the same etc and it seemed to work fine. I have several combos from various years etc so I can't remember one it was now .
But if the pins are the same, orientation etc it should work. Its really just two switches.

Re: Swapping combo relay from a 76 530i to a 77 530i ?

Posted: Sat Jul 20, 2019 4:33 pm
by Lock
My '79 528i has the black plastic combo, but the PO also supplied the original (not working) metal case combo relay. I soldered up a broken link but it still doesn't work.

The black plastic has one extra leg for the 1980+ electric aux air valve (same output as fuel pump), which my car doesn't have but besides that it's identical.

Re: Swapping combo relay from a 76 530i to a 77 530i ?

Posted: Mon Jul 22, 2019 7:50 am
by canada karl
Well I did take the black plastic relay out of the 77 and installed it in the 76 and it fired right up so it's all good. :D