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2003 Passat 1.8T 5 spd. wagon cranks no start no power to fuse 28, 29, 33, 34 or ecu pin 3
I have been trying as an amateur for many days/weeks to solve this issue on my own. After reading many posts, websites, schematics, etc, I have enough knowledge to sound like I know what I am talking about, but I don't. I am regurgitating data that I have learned while trying to resolve this problem. I don't have a schematic and would have a hard time reading one if I did. But I think I have enough exact details to possibly lead someone to tell me what to check. I suspected the ECU but had it tested and checked okay.
I have no power to the engine fuses or the fuel pump fuse, 28,29, 33, 34 either with the key on or while cranking. A code reader does not power up when plugged in and the rpm guage does not move when cranking. The ecu relay DOES have 12 v power to it and it relays it to the opposing pin when the relay is manually held in.
Pin 3 of the T121 connector does NOT have power. I have read and believe that maybe it should have 12 volts with the key on. I would like to trace it from the ECU but without any info it looks daunting. I am hoping that the lack of 12 volts to it could cause all of my symptoms. Everything else on my car operates as it should except the rear power outlet which has a short and blows a fuse instantly. I don't think it is related but just in case I will mention it. I would like to run 12 volts to pin 3 and am tempted to, but I may only create more problems.
 

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inspect fuse 14 for the CCM. i had a failed ccm once that by disabling immobilizer, it disabled ECM, and rendered that exact symptom.
 

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Thanks sipes216, glad to try anything, and now I know that CCM is comfort control module. I'll give it check. Hoping soemome can tell me if it would hurt to apply 12 volts to pin 3 of t121 and see what results. Can I unplug the CCM to remove it as a problem?
 

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If the fuses are good, the fuel pump relay is probably bad. I had a similar issue after my engine swap.
 

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just for my own reasons, which relay is for the FP?

as for removing the CCM, DO NOT DO THAT! it will keep the car from running.
the ecm looks for an OK signal from the CCM directly. if that ccm is not sending out that "on" voltage, then the ecm will not allow a start.
just don't waste your time removing it, it's something else.
 

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The fuel pump relay is under the dash in the 13 relay holder, I don't remember the number. Can't a relay be tested by applying 12 volts and checking the passage of voltage thru the appropriate pins for relaying the power? Thanks Sipes216 and PZ for input. I get the message and won't remove for the CCM. I will check out the fuel pump relay. I am looking at two options if I cannot find any better info. One is using a website that offers pro help for a fee. The other is buying an online service for this vehicle and hope that I can find a wiring diagram that I can read and check into pin 3 on the ECU harness. That wire is a large guage wire and possibly it feeds several other fuses? If I knew it is supposed to be powered then at least I would know it is one specific problem I can understand and very well could lead to the issue. Appreciate it, still looking.
 

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2003 AWM 1.8T looking for input on ECU pin 3 T121, should it have 12v power?

Can anyone tell me if pin 3 on the ECU T121 connector on a 03 Passat 1.8T AWM motor should read 12v. If so, where could I check the other end? Thanks, I have spent much time in research looking for this and so I ask out of desparation.
 

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PLEASE only one thread. I am deleting the other as it is directly related to this one and you even asked the same question here.
 

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The fuel pump relay is under the dash in the 13 relay holder, I don't remember the number. Can't a relay be tested by applying 12 volts and checking the passage of voltage thru the appropriate pins for relaying the power? Thanks Sipes216 and PZ for input. I get the message and won't remove for the CCM. I will check out the fuel pump relay. I am looking at two options if I cannot find any better info. One is using a website that offers pro help for a fee. The other is buying an online service for this vehicle and hope that I can find a wiring diagram that I can read and check into pin 3 on the ECU harness. That wire is a large guage wire and possibly it feeds several other fuses? If I knew it is supposed to be powered then at least I would know it is one specific problem I can understand and very well could lead to the issue. Appreciate it, still looking.
Yes, testing the through voltage on the correct pins will tell you if the relay is working. There are 2-3 relays inside of the fuel pump relay (at least there were on mine) and the power flow should be listed on the cover of the relay (at least it is on the OEM ones).

The wiring diagrams are in the Bentley manual, it's a great resource for any wiring issue.
 

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Discussion Starter #11
I am sure someone (maybe many) knows this but after devouring many forums, consulting mechanics, ecu programmers and trying way too many things, I finally traced the problem to the ABS fuse in location 7. If you have no power to your engine fuses in the lower section of the fuse panel, it is probably because it is all fed from the small ABS fuse in the upper section of the fuse panel. If I had only read this somewhere it would have saved me many frustrating hours. I saw many other VW owners with my problem but I never saw a solution. I suppose one thought is to check every fuse in case of an electrical problem but as an amateur I would not think that a wiper fuse, or a blinker fuse would stop a car from running, likewise an ABS fuse. I wish VW would have put the little engine symbol on fuse 7, probably would have saved a lot of us uninformed and unpaid 'mechanics/electricians" a lot of time and money.
If this helps anyone in the future, please post it here. Thanks for all the suggestions.
 

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Yes, that is quite odd. Glad you were able to figure it out. I know I went through every fuse on my car after the engine swap. Drove me nuts as the whole harness and engine came out of a running car, then it would not work in mine.
 

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Fuse #7 doesn't supply power to any other fuses, but it supplies 12V to T121/3 on the ECM.
The ECM activates the relay/s that supply 12V to some fuses such as 29, 28, and 32.
 

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I'm kinda of having the same issues ran fine when I parked in the garage come back about 4 months later cranks great just won't start...after I did head gasket, valve job, timing belt and water pump oil cooler and all new pigtails for coils...like I said I drove in the shop now nothing I don't get it... I'll try the abs fuse would have never thought...
 
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