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Hi, i have a 2000 Passat 1.8T, over the last few weeks it has twice droped power for a second or two then recovered ( didn't fell like electrical, felt like fuel as it died gently, not sharply. But now it wont start !!! Checked fuel, had no pressure...checked fuel pump voltage, and it only had 3.4 volts,not battery voltage....checked and replaced fuel pump relay,still no go and still 3.4v at pump.. earthed T conection at relay and got fuelpump going with 12v, but still doesn't run...have had ECU checked out and all is ok there. The T conection get its earth signal from the ECU I believe. Can you please help ???

Submitted: 335 days and 11 hours ago.
Category: VW
Value: $15
Status: AWAITING EXPERT REPLY
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Posted by MikeT 335 days and 11 hours ago.

Answer

Keith,

Have you been to the dealer for any recalls in the past? There is a fuel pump replacement recall for Passats. Can you supply me your VIN number. I can check for recalls.

-Mike

335 days and 10 hours ago.

Reply

WVWZZZ3BZ1E032271 Hi Mike, as I mentioned fuel pump works fine when T connection on relay is earthed, or powered up with another 12v power source. Vehicle is not given any check engine warning.

Posted by MikeT 335 days and 10 hours ago.

Answer

But you stated that the pump has 12v when jumped but still will not run. Let me check your VIN.

-Mike

335 days and 10 hours ago.

Reply

Pump gets 12v when T connection at relay is jumped to earth, but still does not start..

Posted by MikeT 335 days and 10 hours ago.

Answer

Well that right there tells me that you pump is faulty. You have supplied battery voltage to the pump, but it is not sending fuel. Easy way to know is to remove the feed line at the motor and see if fuel is coming out of the line. Are you in Europe? I cant seem to find any recall info.

-Mike

335 days and 10 hours ago.

Reply

When I supply 12v to pump directly, I get fuel pressure, when I earth T connection at relay I get fuel pressure. As i mentioned the T connection at relay is get a voltage feed of 3.4v from the ECU, rather that an earth to pull in relay. When relay is externaly eathed to the T connection, the relay pulls in and supplies 12v to pump, and fuel pressure is obtained.

Posted by MikeT 335 days and 10 hours ago.

Answer

Pressure and supply are not the same thing. You can do electrical checks all you want, and chase ghosts all day. Easiest test, is remove fuel feed to see if fuel is coming out when you obtain pressure. What pressure are you seeing when you "jump" to earth? You should not drop below 2.5bar. Have you checked fuse 28? Can you hear the pump audibly when turning key to on posistion.

-Mike

335 days and 9 hours ago.

Reply

Pressure is easy 45psi and holds that, and yes when turn key on while earthing T connection i can hear pump running.

Posted by MikeT 335 days and 9 hours ago.

Answer

Did you check fuse 28? Did you look for fuel supply from the feed line?

-Mike

335 days and 9 hours ago.

Reply

I can check at the moment as the ECU is not back till 2-morrow from the electronic people. But from memory fuse 28 doesn't get power till fuse 32 gets power from pump relay..

Posted by MikeT 335 days and 8 hours ago.

Answer

Fuse 28 is power to fuel pump. You are getting ahead of yourself, thinking too deep into the concern. All fuses have 15 or 30 circuit power. They dont get power from other fuses. They work with ignition on or off. Thats how the fuel pump primes before you start the motor. For me to help you the best I can, I need you to follow my advise.

-Mike

335 days and 8 hours ago.

Reply

I understand your view point. When i install ECU 2-morrow I will checkout what you are saying. Cheers Keith.

Posted by MikeT 335 days and 8 hours ago.

Answer

Once you install ECM dont forget to check BOTH sides of the fuse for 12v.

-Mike

335 days and 8 hours ago.

Reply

Will do Mike..

 

Cheers

 

Keith

334 days and 13 hours ago.

Reply

Hi Mike, I have connected ECU and powered up. With ignition turned on there is NO power at fuse 28, but that is surely because relay has not pulled in ???

Posted by MikeT 334 days and 7 hours ago.

Answer

The relay has to be plugged in. Is the fuse visually good?

 

-Mike

334 days and 7 hours ago.

Reply

Hi Mike, I have got vehicle going at the moment, I thought I would check power feeding from D15 ( ignition switch) to fuse 32, and it appairs there must have been a poor conection at switch, as thinks are running ok now.. have there been issuses with ign switches in the passed???

Posted by MikeT 333 days and 23 hours ago.

Answer

Keith,

There really hasnt been any issues with the ignition switch in the Passat. That seems wierd that the 15 circuit is faulty. That is the ignition switched circuit, not start (which is 50 circuit at the switch) Either way glad its running. Did you replace the switch or find a short circuit in the wiring?

Please if I have been AT ALL helpful, please accept. Otherwise we do not get compensated by the site for our time.

Thank you

-Mike

333 days and 14 hours ago.

Reply

Hi Mike, I went to start car again later in the afternoon, and guess what, it wont go again!!!!! Fuse 32 gets power through D15 circuit, via A2 (Positive connection (15) in dash wiring harness) could there be a connection fault there.???..or....also D15 powers J285 (Display control unit in dash insert) then goes on to power coils.. could there be a fault there???.....One thing I had noticed lately was the Red dash read outs have from time to time not been as bright sometimes.

Accepted Answer

Keith,

Please dont take this the wrong way. You have to know how the circuits work to correctly daignose the vehicle. Fuse 32 powers the Fuel pump relay to power the fuel injectors, all going through J220 (ECM). The power comes from circuit 15. A2 is a soldered connection in the instument panel wiring harness (this has nothing to do with J285) Do you have power at both sides of fuse 32? If so you should have 15 and 30 power (12v) coming out of the relay.If so and the car still doesnt start. You should repalce the fuel pump relay, which is pretty common. If you were to scan the vehicle I would suspect you would have about 15 faults all being short to ground faults to many different components.

If you would'nt mind, please accept. We are pretty deep into this. I will not be compensated for my time if the advise is not accepted.

Thank you.

Please return with results from my above questions.

-Mike

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Expert: MikeT
Pos. Feedback: 98.7 %
Accepts: 274
Answered: 12/10/2008

VW Technician

VW dealer registered and certified. 10+years VW/Audi experience. Avid VW enthusiast.

332 days and 14 hours ago.

Reply

Hi Mike,

 

There is no power at either side of fuse 32...i have had vehicle to VW dealer, and they scaned no fault...this fault appairs like a loose connection somewhere ??? and going by the wiring diagram it should be between A2 connection and D15 ign circuit. I respect your comment regarding the understanding of circuits etc, although I have never worked on late model vehicles as a tech, I've been in the motor industry for 33 years, i did my time on GM and Toyota from 1975-1983 aftermoving into Sales and Management till now, during that time I have been involved in VW,Audi,BMW,Peugeot,Nissan,Mazda,Mecedes,Holden,Jeep,Chrysler,Dodge,Suzuki,... Look Forward to you thoughts.

 

Cheers Keith

Posted by MikeT 332 days and 10 hours ago.

Answer

A2 is a soldered connection in the dash panel harness. There are MANY different components on the A2 circuit. D15 is just key acc postion, not start postion (50 circuit). I would say that you have a open circuit between the fuel pump relay or fuse 32 and the ECM (J220). It seems like you have a good wiring diagram. Check for continuity beween the relay, fuse and ECM

 

-Mike

332 days and 7 hours ago.

Reply

Thanks Mike, i will check out and let you know.

 

Cheers

 

Keith

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