Hi All,

 

Does anyone have or have a link for the fuel pump wiring diagram for a mk1 Octavia VRS I have been looking online but cant find anything!

 

Cheers

Alex

not much help but they are (VAG) fed from the main relay but actuated by the ecu which controls the fuel pump relay,  the feed for the ignition system often use the same feed ---  if you check the connector at the pump end  and look for the earth,  QED the other wire 

 

is the live feed 

Blue/red wire from fuse 228 is the live to the pump. Brown at the pump connector is pump motor earth.

Fuse 228 and a few others are fed from the fuel pump relay, position 4 of relay panel, by a blue wire.

 

Thanks guys going to check the feed in the morning & if no feed pull the relay & open it up see if the contact is shafted, from reading through old posts its appears this is a common point of failure?

Hi All,

Can anyone advise on what voltage I should be getting at fuse 28 (Fuel pump) as after testing I am seeing only 1.8v & assumed I should be getting around 12v?

 

Many thanks

Alex

Should be 12ish.

Thanks Wino.

 

I have establish that fuse 28 is only receiving 1.8v which is clearly the source of my problem can anybody tell me were this is fed from or does any one have a wiring diagram I can study as it appears this is a permanent live I have verified this by removing the Relay & testing the fuse the ignition in the on & off positions,

 

Cheers

Alex 

Fuse 28 (designated 228 in the wiring diagrams for some reason) is fed by the fuel pump relay via a blue wire, as said earlier. The other side of the relay contact is indeed a permanent 12V, fed by a 50A fuse in the battery fuseholder.

I'm afraid I don't know enough about the fuel pump relay in your car to help you to test it, but I suggest trying another one if you can find one without spending too much.

 

 

 

have just been to double check, with ignition & relay unplugged I get no voltage across the fuse turn ignition on & I get 1.8v this I think indicates that the fuse is before the relay not after & potentially a wiring or ignition switch issue.

 

I may just order a 2nd hand relay just to test as I can get one for £10 from ebay

Ah hang on the relay is triggered by the ignition then hence the 7 pin relay thus completing the circuit & allowing 12v 

 

 

Edited 27 December, 20178 yr by alex.hayes73

When I've walked the dog I will sketch the circuit to show you where all those 7 pins go. The info I'm using is copyright (from erWin) otherwise I'd post a screenshot.

Now I'm confused because there doesn't seem to be a 1:1 correspondence between what I'm looking at and the diagram on the side of that relay.

Can you confirm year and engine code of the car?

 

 

Ah, just found a later diagram, here's the deal:

 

Pin 4/15 =  Ignition 12V

Pin 2/30 = permanent 12V from fuse 2 on battery

Pin 8/87 = relay output to fuses inc. fuel pump no. 28

Pin 6/31 = earth

Pin 3/C =  connection to airbag control unit (only on cars where passenger airbag can be disabled)

Pin 1/MOT = connection to crank sensor

Pin 9/TK = connection to door contact switch

 

If you do get another relay to try, make sure it's the same part number as yours, including any suffix letter, it looks like the earlier version was different.

Edited 27 December, 20178 yr by Wino

Top man thank you very much for your help :-)

 

I'm going to test the feed on Pin 2 from fuse 2 on bat but I have ordered a new Relay £38.00 from ebay  :-)

 

I also this guide on VWVORTEX http://forums.vwvortex.com/showthread.php?5427024-Testing-Fuel-Pump-Problems-amp-Solutions-thread

 

Think once mine is running I will collate the information you have provided on the pin-outs with the below & see if it can be added to the troubling shooting page or similar :-)

Questions to help diagnose:

1) when you open the driver door, do you hear the buzzing noise from under the car? If you hear that, your fuel pump is working. Your problem is not the fuel pump, fuel pump relay, or fuel pump fuse. Stop reading this thread, it does not apply to you. 

If you do not hear the buzzing noise when you open the driver door, the fuel pump is not priming. Continue to step 2.

2) Does your interior dome light turn on when the door is open? Does the door chime sound when the key is in ignition and the door is opened? If the answer to both of those is "no", then your door latch microswitch is not working correctly. Go search for threads on how to fix that problem. 

If the dome lights turn on with the door open, continue to step 3.

3) Is fuse #28 blown? That is the fuel pump fuse. 
If it is blown, try replacing it (15A fuse) and see if normal operation resumes. Warning: blowing that fuse is usually indicative of a relay and/or pump going bad! If it blows when you put a new fuse in and turn the ignition on, continue to step 5. If nothing happens when you replace it, go to step 4.

4) Test the fuse location with a test light or mutimeter to see if there is 12V+ when the key is on. If there is 12V+, go to step 6. If there is not, go to step 5. 

5) Check fuel pump relay. It's the 4th from the left on the bottom row of relays, under the dash. The label next to it says "diesel F". It's relay #409, part # 1J0 906 383 C. Costs about $43 online, and $66 at the dealer. 

I'll let the experts weigh in here on how to "properly" test the relay. 
Here are two possible methods that don't involve using jumpers in the fuse block or trying to wiggle a multimeter in there:
1) Borrow a 409 relay from anyone else who has a Mk4. Swap it in. If your fuel pump works with their relay in there, you've found the problem. This is by far the easiest way to test. Everyone knows someone else with a Mk4 - doesn't matter what model. 
2) Go to step 6 & test the fuel pump itself, thus determining the relay was faulty. 

6) Test fuel pump & connector. It's located under the right rear passenger seat. Remove the lower cushion, and fold the square flap forward to access the panel. Remove the 3 screws and pry up the coverpanel gently. Check to see the main connection is in decent shape. Some of them are defective and come loose. Use a multimeter and see if it's getting voltage at the outer connections on the terminals. If there is no voltage, the relay may be the problem. 

If you have a small battery (RC car battery works nicely) for testing, use the outer connections on the cover to the fuel pump to see if the pump operates when you apply current. Alternately, you can use a square 9V battery with a couple of leads from it. That should give enough current to see if the motor at least turns with current applied. It's a loud little thing, will be very evident whether it works or not. 

If the motor works when you apply current, the relay may be faulty or the connector may be faulty. You'll have to do some more circuit testing to see what the deal is.

If the motor does not work when you apply current, the motor is toast. Replace it.

38 minutes ago, Wino said:

Now I'm confused because there doesn't seem to be a 1:1 correspondence between what I'm looking at and the diagram on the side of that relay.

Can you confirm year and engine code of the car?

 

 

 

MK1 VRS

53 Reg early 2004 car

AUQ

4 minutes ago, alex.hayes73 said:

 

MK1 VRS

53 Reg early 2004 car

AUQ

Hmm, the diagram that I found which did match the info on the side of the photographed relay was only supposed to apply to cars from October 2004 onwards.

What's the VAG part number on the relay?

Hello there,

is anybody know where is the problem? I also have same symptoms as Alex.hayes73.

 

I have establish that fuse 28 is only receiving 1.8v

 

Thank you for answer.Milan