Power to fuel pump but no prime (Any help please!)

[Darbshaw]

OP, what is the production date of your car?

09/2003


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[sapote]

Low side (ground) switched from what I can see!

This diagram shows a electromechanical relay. I believe all or some US cars have semiconductor relays and the control can be different.

[sapote]

09/2003


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manual or SMG? pls next time provide these basic but needed information.

[sapote]

This DME is for 2003/03+ and there is no fuel pump control on pin10 or pin11. It uses serial CAN bus.
Edited: This seems to be not for USA cars.

Pin assignments at plug connector X60004

1		Not used
2	A	Activation, heating for fuel tank leak diagnosis module	Diagnostic module, fuel tank leakage
3	A	Activation Secondary air pump relay	Secondary air pump relay
4	A	Activation Electric fan	Electric fan
5	M	Ground Secondary air, hot-film air mass meter	Secondary air, hot-film air mass meter
6		Not used
7	M	Ground Pedal position sensor	Pedal position sensor
8	E	Signal Pedal position sensor	Pedal position sensor
9	A	Voltage supply Pedal position sensor	Pedal position sensor
10		Not used
11		Not used
12	M	Ground Pedal position sensor	Pedal position sensor
13	E	Signal Pedal position sensor	Pedal position sensor
14	A	Voltage supply Pedal position sensor	Pedal position sensor
15	E	Signal Secondary air, hot-film air mass meter	Secondary air, hot-film air mass meter
16		Not used
17	A	Speed signal	Diagnostic connector
18		Not used
19	A	Activation E-box fan	E-box fan
20	A	Activation, pump for fuel tank leak diagnosis module	Diagnostic module, fuel tank leakage
21		Not used
22	E	Signal Processed wheel speed, rear right	ABS/ASC unit ABS/DSC unit
23		Not used
24	E	Signal Brake light switch	Brake light switch
25	E	Signal EAC sensor	EAC sensor
26	E	Terminal 15	Fuse F29
27	E	Data link MFL	Volute spring
28	E	Signal Brake light test signal	Brake light switch
29	A	Activation Relay, A/C compressor	Relay, A/C compressor
30	A	Activation, valve for fuel tank leak diagnosis module	Diagnostic module, fuel tank leakage
31	A/E	Local CAN-bus low	Control unit for electronically controlled fuel pump
32	E/A	Signal Diagnostic link TXD	Diagnostic connector
33	E	Signal Electronic vehicle immobilisation	Electronic immobiliser control unit
34		Not used
35	A/E	Local CAN-bus high	Control unit for electronically controlled fuel pump
36	E/A	Signal CAN bus high	Connector, CAN bus
37	E/A	Signal CAN bus low	Connector, CAN bus
38	M	Ground Coolant outlet temperature	Coolant outlet temperature sensor
39	E	Signal Coolant outlet temperature	Coolant outlet temperature sensor
40		Not used

[Darbshaw]

Okay I apologize I did not realized that was relevant.
SMG
Coupe With sunroof

So from with my pin 10&11 unused where does that leave me for further troubleshooting? Just checking for power at the relay input pin?

Edit: just saw it was pin 30 or 31 to control the fuel pump. Is this where I should be looking to ground? Mobile is a pita to look back at old info while replying

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[Martyn]

Sorry, didn't mean to throw you off with my euro wiring / assumptions.

[SliM3]

Sorry, didn't mean to throw you off with my euro wiring / assumptions.

Martyn, that WD is correct. It shows the mechanical operation & not the solid state, but the supplied ground is pulsed (PWM) from the DME, based on the EKP duty cycle map. The actual pulse is 0 VDC > 5 VDC (㎲ hold) > 14.1 VDC. Obviously a duty cycle of 100% will be continuous 14 VDC.

[sapote]

Okay I apologize I did not realized that was relevant.
SMG
Coupe With sunroof

So from with my pin 10&11 unused where does that leave me for further troubleshooting? Just checking for power at the relay input pin?

Edit: just saw it was pin 30 or 31 to control the fuel pump. Is this where I should be looking to ground? Mobile is a pita to look back at old info while replying

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Hopefully you don't need to deal with pin31 and 35 CAN bus wires. Don't ground those pins or wires!

It seems the DME commands another module via CAN bus to energize the pump relay. For now you should check the 8-pin relay: jumper from pin2 to pin6 should run the pump. If not then either bad pump or bad wire from pin2 to pump, or pump ground wire.

[Darbshaw]

Okay thank you a ton. I am sorry for the overall lack of knowledge in this area. If there is an easy way to learn all of this I’m all for it

Iirc, when I was testing voltage on my relay wires there wasn’t power going to either pin 2 or 6. I will test this tonight for sure.

If it matters, I had zero issues with my pump before my rebuild. Mainly before my sparking incident. Hopefully I’m not chasing a wire through my car.


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[Darbshaw]

Hopefully you don't need to deal with pin31 and 35 CAN bus wires. Don't ground those pins or wires!

It seems the DME commands another module via CAN bus to energize the pump relay. For now you should check the 8-pin relay: jumper from pin2 to pin6 should run the pump. If not then either bad pump or bad wire from pin2 to pump, or pump ground wire.

Okay so I have no activity when running from pin 2 to 6.
Tested voltage with the relay plugged in and key to position 2 on a disconnected pump plug was roughly 12.5v spike and settling around 10.8v. I don’t know how to test the fuel pump While it’s plugged in.

I know it’s not a bad pump since it’s brand new in box.

Is there potentially any other kind of ground that I could have missed when wiring in the engine harness? Or what would be the next step.
I’d assume fuel pump to ground is going to be my easiest one to find and test first


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[sapote]

pump connector: pin1 is the Brown wire and it's grounded. You should check with meter.
Relay connector: pin6 is 12v via the Fuse 54. So it pin2 is not 12v then check voltage at fuse 54. Once you have pin6 with 12v then jumped it to pin2 should run the pump. Hope you have a meter; if not get one.

[Darbshaw]

I feel extremely dense for this. The second fuel pump relay, the green one. Is this next to the black 8 pin or in the glove box? From what I could find on newtis and realoem I cannot find anything that even points to this being used or anything.

I swapped out the one next to the 8 pin, if its the one in the glovebox then I may have caused all of this headache for nothing.


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[SliM3]

Green relay in the trunk is rear window defrost.


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[sapote]

8-pin Relay with 9-pin connector in the trunk shown in post #7.

[Darbshaw]

Green relay in the trunk is rear window defrost.


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Well I feel absolutely dense, I’ll try this and see if all this headache and frustration was for nothing


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