2003 S211 E320 petrol crank no start M112 engine

[E240estate]

Hi, as title, no fuel at fuel rail, car can be made to start by applying 12v directly to the fuel pump.
Fuel pump does not come on when key turned on. No 12v at fuel pump connector when ignition on.
Power on both sides of fuse, fuse ok.
Relay from rear SAM tested off the car and works perfectly.
Tested all relays in front SAM all good.
Car not sending 12v to fuel pump
No codes.
Sudden failure.

Next step for me is to remove and inspect rear SAM, correct? Or any ideas from anyone on here much appreciated as always.

 

[pcthrillrider2]

next step would be to a mercedes idie for me

 

[Jobsworth]

From memory the fuel pump relay is on the rear SAM, very bottom one iirc. Try closing the relay manually, or using a jumper lead to see if the pump runs. If not it must be in the wiring between SAM and pump. If it runs you need to look further at the rear SAM.

 

[E240estate]

From memory the fuel pump relay is on the rear SAM, very bottom one iirc. Try closing the relay manually, or using a jumper lead to see if the pump runs. If not it must be in the wiring between SAM and pump. If it runs you need to look further at the rear SAM.

Jumped the relay earlier, still no pump running. Can take the SAM out and check for obvious damage, but beyond that I don't have the software to code in a new SAM.

 

[BlackC55]

From memory the fuel pump relay is on the rear SAM, very bottom one iirc. Try closing the relay manually, or using a jumper lead to see if the pump runs. If not it must be in the wiring between SAM and pump. If it runs you need to look further at the rear SAM.

Terminals 30 and 87

 

[E240estate]

I can't see the pin numbers anywhere on the SAM unit

Tested for voltage on the small or 'input' terminals of the fuel pump relay panel, I have a constant 12v on one side but the other side does not ground whether the key is on or off. I am guessing that the SAM switches it to ground with key on.

The large or output pins of the relay fuse panel show 0V between themselves, and each between ground, whether the key is on or off.

Realise I may be oversimplifying or misunderstanding how the switching works.

I see red/green and light brown wires exiting the rear of the SAM unit via a multi plug. Will these be the same red/green and light brown I see at the fuel pump, and can I eliminate these by testing for continuity? Only reason I ask is at the fuel pump, they appear to route towards the front of the car, ie away from the rear SAM unit I'm testing on.

Many thanks all

 

[BlackC55]

The pin numbers are on the relay.

 

[E240estate]

Something a bit odd, the relay has pins numbered between 1 and 5.
There's never been a relay in the bottom location.
What I think is the fuel pump relay is in the third location up (above a square grey relay), labelled spare relay 2 on diagrams.
Car is a Japanese import being originally sold there not sure if a different relay layout because of that?
The fuel pump relay I think is a slimmer rectangular black item, as opposed to a standard cube relay.