Car won't start - ECM relay fault code, drivers lock issue, low volts at fuel pump

[DAC84]

My leon has had an intermittent starting issue for a while.

The full story is below but to cut to the chase there's low power at the fuel pump. Using advice from here I have tried the following:

- new battery (tested today 12.6v)
- new ECM relay (428)
- checked fuse 28
- checked fuel pump relay 409. Clicks fine but unsure what pins to check for volts.
- checked new relay 428. 11.6v at pin 85 and 86. 1ohm at 30 and 87.
- checked fuel pump volts - 1.7v.

The drivers door lock is also temperamental and today it doesn't lock centrally, only using the key and its very laboured, almost sounds dead.

Any ideas and also what pins do I use to check fuel pump relay and relay board?


Full background
First time this happened the recovery guy tapped the ECM relay a few times, fiddles with a few things, it started and didn't happen again for 6 months.

Now it's happened again twice in 2 weeks.

Last week I changed the battery but no luck so got recovered home. The next morning I checked and it was still dead. I scanned with VCDS and it showed the following codes:

17069 - ECM Power Relay Control Circuit (J271): Open Circuit
P0685 - 35-10 - - - Intermittent
16795 - Secondary Air Injection System: Incorrect Flow Detected
P0411 - 35-00

Checked again an hour later and the fuel pump primed and it started.

Today the mrs has got in the car and it won't start again. This time I scanned and it has the same codes above plus:

17925 - Power Supply Relay for ECU (J271 or J363): Electrical Malfunction
P1517 - Intermittent

Any help appreciated as we have one car between us...

 

[ibizacupra]

you have tried a new relay?? checked contacts not burnt etc?

 

[DAC84]

Not a new pump relay, I have fitted a new ECM relay though. The fuel pump relay clicks when I fit it but I will test it properly.

I've seen a thread on vortex relating to the door lock, which could be causing this problem because the car thinks the door isn't open and therefore doesn't switch the fuel pump on.

Clutching at straws here though!

 

[mty12345]

Not a new pump relay, I have fitted a new ECM relay though. The fuel pump relay clicks when I fit it but I will test it properly.

I've seen a thread on vortex relating to the door lock, which could be causing this problem because the car thinks the door isn't open and therefore doesn't switch the fuel pump on.

Clutching at straws here though!

If it's immobiliser related, because it still thinks the car is locked etc, then you should have the yellow immobiliser light flashing on the dashboard. Otherwise like bill says it sounds like a relay to me too. Sometime they check out ok when testing but then occasionaly they will fail to hold the contacts closed under full load.

 

[DAC84]

If it's immobiliser related, because it still thinks the car is locked etc, then you should have the yellow immobiliser light flashing on the dashboard. Otherwise like bill says it sounds like a relay to me too. Sometime they check out ok when testing but then occasionaly they will fail to hold the contacts closed under full load.

Just tried it and no dash lights flashing when I try to start it up.

Another odd one is that I've removed the fuel pump relay and thought I'd check the volts at the pump, assuming it'll now be 0v instead of 1.7v, but it was still the same. I'm either not testing it correctly (multimeter in the two larger wires), the relay isn't required for some volts or the relay makes no difference, which would suggest it is duff!

I'll try and get hold of a new one tomorrow to rule that out.

 

[Will_s87]

fuel pump volts seem very low as you have pointed out,
can you check the resistance of the negative connection between pump terminal and battery...
just an idea..

 

[mty12345]

fuel pump volts seem very low as you have pointed out,
can you check the resistance of the negative connection between pump terminal and battery...
just an idea..

As will says here, surely the voltage at the pump should be near enough 12v, not 1.7v?

 

[DAC84]

As will says here, surely the voltage at the pump should be near enough 12v, not 1.7v?

Yes it should be so I need to work backwards to see where it drops. I'd of thought it would be either ~12v or 0v rather than 1.7. I've got the wiring diagrams from the bentley manual so I'll check all of the earths this morning and work back from the pump.

Failing that I'll try and get a new relay, but my local dealer takes a working day to get any part in and I cannot see them listed on ECP or GSF.

 

[DAC84]

Just an update...

Test voltage at the pump again and it reads 1.7v before the key is in the ignition, then it gets a shot of voltage around 12v when the key is turned and drops back to 1.7v. When turning the car over the pump is getting 10.7v contantly.

So, is 10.7v on start up too low, otherwise it looks like the pump is knackered?

 

[ibizacupra]

Not a new pump relay, I have fitted a new ECM relay though. The fuel pump relay clicks when I fit it but I will test it properly.

I've seen a thread on vortex relating to the door lock, which could be causing this problem because the car thinks the door isn't open and therefore doesn't switch the fuel pump on.

Clutching at straws here though!

drivers door open will not prevent you from starting the car.
On initial open of door it should prime but thats all

 

[ibizacupra]

still not replaced the fuel pump relay?

 

[DAC84]

ha, not yet as I'd rather fix the problem once it's diagnosed. I've got into replacing each part until it's fixed and it gets expensive.

The bentley manual says the correct voltage for the pump on start up is battery -2v so 10.7 is correct, which would suggest the pump is knackered?

 

[DAC84]

drivers door open will not prevent you from starting the car.
On initial open of door it should prime but thats all

Noted, thanks. The interior lights comes on when I open the drivers door so I think that can be ruled out of causing the starting issue.

 

[mty12345]

ha, not yet as I'd rather fix the problem once it's diagnosed. I've got into replacing each part until it's fixed and it gets expensive.

I'm with bill, i think for the £10/£15 that a fuel relay costs you should just try replacing it. If it was a £120 MAF etc it might be different.
Even if the contacts on the relay are closing, they could be dirty and burnt from arcing and not able to carry enough current for the pump. Even if it turns out not to be the case you've got one in the glovebox for when it does fail anyway. Your money and all that, but if it was my car i'd just go to gsf etc and get a relay.

 

[ibizacupra]

ha, not yet as I'd rather fix the problem once it's diagnosed. I've got into replacing each part until it's fixed and it gets expensive.

The bentley manual says the correct voltage for the pump on start up is battery -2v so 10.7 is correct, which would suggest the pump is knackered?

its a fcuking relay dude

 

[Will_s87]

if you want to prove the relay is not the problem;
1) unplug relay
2) short out the two main contacts.

 

[DAC84]

its a fcuking relay dude

Usually I would think the same but it's a £54 relay, which as it turns out was fine as it was the pump...

New pump fitted and cars running again.

Thanks all for your advice.