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Relays

732 views 7 replies 4 participants last post by  dm_n_stuff 
#1 ·
My 1972 280 SE 4.5 is in need of relays. The relays I have are the tall cylindrical silver colored relays for the aux fan and the starter valve, I believe. They sit just behind the ECU for the fuel injection system. The part number is : 000 542 97 19. Apparently no longer available.

Any hints or ideas of where to go from this point?

Thanks
 
#2 ·
I found a listing for them at three or four different vendors. Can't verify if they are actually physically in stock but they're out there.

They are just standard relays. A bit of wire, 5 minutes of soldering and you can use the standard "spade" end style Bosch relays available from any parts store. $3-$5 USD.
 
#4 ·
dm n stuff

thanks for the ebay links. I saw these as well, but these are five prong relays and the original ones are four prong.....
 
#5 ·
Relays come in two flavors, normally open, normally closed. A four prong is always a normally open. A five prong can be wired either way depending on which pins are connected.

On the bottom of the relay, the connections are numbered: 86 is power to the coil (the thing that turns the relay on/off) and 85 is coil ground. 30 is power to the relay for the component you want to control (fuel pump, lights, etc) and 87 and 87a are power out of the relay (actually goes to the conponent). 87 will have power when the relay is energized. 87a will have power when the relay is not energized.

You can use a 5 pin relay in a 4 pin slot because the 87a pin is not connected to anything in the harness.

You just have to make sure you are buying the right relay (round pins for the old MB relays and spades for modern relays).
 
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