1994 w124 e320 estae

[tonyhtb]

Hi all,

Well its decided not to start so friendly RAC man arrived and started checking, fuel pump fine but not getting any current . So we have a root around fuel pump and OVP relay and these appear fine, however what I would like to know is where each one of these should be so assuming the rear edge of the batter is our datum which should be closest to the battery. Sounds like a dumb question but I have read sometimes these get swapped around.

 

[GP801]

OVP relay sits behind the battery - its the one with a fuse on top. Fuel pump relay is under the cover behind the fuse box. They are not interchangeable. Either can cause failure of the supply to the fuel pump. Fuel pump relay was £18 and OVP £65 both from MB for our S124 E280 so not too bad if they have gone.

 

[tonyhtb]

Ok thanks, so when you look behind the battery cover there are two relays on the left of the ecu, one is green whats this for?

 

[GP801]

Not sure about that one. We had intermittent lack of power to the fuel pump. Ended up replacing both relays to sort the problem. The solder joints deteriorate over time. Given the relativley low cost of new ones did not attempt to repair the dodgy ones but it can be done.