2002 E46 318i Convertible fuel pump relay

[mrscalex]

I'm being driven round the twist trying to find the fuel pump relay on my brother in law's E46 convertible.

Every instruction I can find on the internet says it's the left hand one in the bank of 4 when you remove the glovebox. But it's not. I jumpered it and it was the horn!

I suspect the convertible must locate it's relays somewhere else to the saloon. So I think it may be another one in that bank of 4 or somewhere completely different like behind a trim panel somewhere near the fuel pump, eg boot.

Does anyone know for sure where this relay lives? I'm trying to diagnose a non-start problem which I suspect is the crankshaft sensor. But I want to rule out something daft as changing that sensor could be a big job.

 

[pgunter]

I will ask my E46 breaker for you.. Nic is good for parts so might have an idea where that might be located.

 

[pgunter]

And here’s your answer.

 

[mrscalex]

Very good of you thanks.

Would it be possible to ask him which relay it is on a convertible? It is not the first in the bank of 4. As per my original message all the how tos say that it is but it’s the horn in this car.

 

[pgunter]

Have you considered it might be the first of four from the other direction ?

 

[mrscalex]

No because I've been looking at diagrams (including realoem) that show it as the first. And people describing it as first on the left.

I reckon I've seen 20+ references to it being first on the left. But it's not on this car. And I'm guessing it's because it's a convertible.

 

[pgunter]

Nic has said it’s the first one too. Real OEM has it as a green relay.

 

[pgunter]

That’s a 318 vert.

 

[mrscalex]

Nic has said it’s the first one too. Real OEM has it as a green relay.

Thanks.

Well unless the car has been molested or has a very strange issue the horn beeps when I jumper that first relay!

 

[pgunter]

Can you not spot a similar relay to the green OEM one ?

 

[mrscalex]

Can you not spot a similar relay to the green OEM one ?

I’m just going to have to jumper each light green relay until I get something at the pump. There is a bank of 4. 3 light green and one brown. I don’t really like kicking something in that I don’t know what it is. But I’ll have to! I expect one at least is the fog lamps.

I’m wondering if someone has had the array of relays out and not put them back in the right order. I doubt it though as there isn’t usually enough slack in the harness.

 

[pgunter]

As Nic said, maybe you should remove the fuel pump or test if a voltage is actually reaching it before playing around with the electric harness area.

 

[mrscalex]

As Nic said, maybe you should remove the fuel pump or test if a voltage is actually reaching it before playing around with the electric harness area.

Fuel pump is fine. We’ve had it out and tested it. I just want to prove the DME is not sending the ground to the relay.

 

[mwpe]

My E46 compact had a non start problem which baffled the local main dealer for three visits. It was the fuel pump relay.

 

[mrscalex]

I've spent about 6 hours on it so far. But most of that was trying to get INPA to work properly with it and then trying to re-synch the EWS to DME as I thought it was a security lock out. What I didn't know is that INPA is for older cars like Z3s and I needed BMW Scanner and a new cable for the E46. That's an impressive bit of software compared to INPA.

But that time is an investment in being able to help him maintain his car in the future.

If I can find the relay then you can tell quite a lot from putting a meter on the various pins and jumpering it to see if the pump runs.

There is a camshaft and crankshaft sensor error. I suspect the crankshaft sensor has gone. But diagnostics can be misleading sometimes. I just like to test everything I can before going to the trouble of changing parts unless they are quick and easy to change. Crankshaft sensors aren't easy to change, on an E46 most people end up taking the inlet manifold off and I suspect the camshaft error is only throwing an error due to the crankshaft sensor.

 

[mrscalex]

Through a process of trial and error it turned out the fuel pump relay was in position 3. The horn as we know was position 1. And presumably it was the fog lamps on position 4.

So contrary to every reference on the internet and the E46 specialist above this seems to be the only E46 on the planet that does not have the fuel pump relay in position 1. Very strange!

Testing proved the fuel pump was okay, relay was okay, fuse was okay and wiring was okay.

I'm as certain as I can be it's the crankshaft sensor.