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Discussion Starter #1
Hello to all. New member here. My step-son has an 03' V6 4Motion sedan with 115,000 miles on it. He's had the car for about 4 months, and it is pretty immaculate. There are no service records unfortunately. I received a call from him saying that the car would not start, although it seemed to turn over fine. The EPC light is on as well as the check engine light. The car was driven the previous evening without incident and no CELs on. I have VCDS(because I have 6 Mk4 Jettas), so I went and scanned for codes. There was a code for Bank 1 warm up catalyst 16805 (P0421), and a handful of codes for the A/C central flap motor for air flow direction. There was also an airbag code and a code for the driver's seat memory emergency switch being active. There were no other codes. I cleared all codes, but the EPC light stayed on and never even blinked off for a second. The A/C blend door codes came back as did the airbag code and the seat memory code. I though I would have a code pointing toward the EPC warning, but none of those seem to be related. The only odd thing I noticed was that I couldn't hear the fuel pump cycle when I turned the key to the 'on' position. Naturally, I tried multiple times, but never heard the pump. I know I can hear the pumps cycle in my Jettas, but I don't know if I would be able to hear the Passat pump cycle or not. I am suspicious of the fuel pump now. If the EPC light is active, are there circumstances where the ecu will not power the fuel pump, as a safety per-se? I didn't have any tools with me, so I didn't check anything else.

Can anyone shed any light on this situation? Even if it's just basic EPC information. As it stands, the car is 'down'...just not starting although it is turning over very well. What should I check? Thanks for anything you can add.
 

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Two quick things:

1) Crank the car for over 5 seconds continuously. The Engine Speed Sensor (ESS) is a common failure in these cars. If the ECM doesn't see an ESS signal, it doesn't fire the injectors or coils, thus no start. 5 seconds of continuous cranking will bypass that requirement. If that's the issue, the car will start, EPC light will remain on, and idle will be a little high.

2) Fuel pump runs a couple of seconds when you first open the driver's door, but immediately when cranking. Easy way to check fuel pump is fuse 28: it's downstream of the FP relay, immediately upstream of the pump. Measure resistance to ground at the fuse (car off)--you're measuring the pump resistance, around 1.5 ohms is good. Over 100 ohms is failed pump. (If you have a meter.) If you have a fine probe, measure through the little holes on the back of the fuse (fuse still installed). Fuel pump is a common failure, but it usually gives a little warning.

You can probably test run the pump with VCDS (output tests), but I can't walk you through it.
 

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Even a failed fuel pump wouldn't generate any fault code. But the fact that you are getting whole bunch of other codes tells me that your focus should also be toward other areas besides the pump. I would also check the MAF and see if that's working in the spec range since you are reporting air flow fault code (just a thought).
 

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It just occurred to me, since you have VCDS...

You can look at the engine speed in the ECM measuring blocks to immediately know if the ESS is working.
 

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Discussion Starter #5
Two quick things:

1) Crank the car for over 5 seconds continuously. The Engine Speed Sensor (ESS) is a common failure in these cars. If the ECM doesn't see an ESS signal, it doesn't fire the injectors or coils, thus no start. 5 seconds of continuous cranking will bypass that requirement. If that's the issue, the car will start, EPC light will remain on, and idle will be a little high.

2) Fuel pump runs a couple of seconds when you first open the driver's door, but immediately when cranking. Easy way to check fuel pump is fuse 28: it's downstream of the FP relay, immediately upstream of the pump. Measure resistance to ground at the fuse (car off)--you're measuring the pump resistance, around 1.5 ohms is good. Over 100 ohms is failed pump. (If you have a meter.) If you have a fine probe, measure through the little holes on the back of the fuse (fuse still installed). Fuel pump is a common failure, but it usually gives a little warning.

You can probably test run the pump with VCDS (output tests), but I can't walk you through it.
Hi! Thanks for joining in.
The car is 20+ miles away, so I'll have to relay some basic things to him to try on his own...as it's time for him to learn as well :)
1) So, there is no fault code for missing ESS signal? Sincere question there. If this sensor goes out, I will not get a code? I just want to make sure I am understanding. I realize that maybe it is not monitored, but want to make sure.

2) Hmmm, ok. My Jettas cycle the pump when the key is turned to the 'on' position. The pump may also prime when the driver's door is opened too, but I am not sure. I know I hear it with the key cycle though(on my cars). I'm not sure if I would hear the pump run when cranking the engine. I never heard it under any condition today. I did look at fuse 28(blue 15A I believe). It 'looked' fine, but I didn't have my meter to verify. If I have to go back, I'll be loaded with all of my stuff. There may have been fuel pump warnings or other drivability oddities that 'car' people might have noticed, but I don't know here. Neither step-son or his wife have any car experience whatsoever, so I'm having to start from 'scratch'.

I'll have him 'long crank' the car and see if that allows it to start. The battery voltage was just a hair under 12v today(via vcds), but was still cranking fine. I imagine that the battery will start to drain fairly soon and of course he has no charger. Oh, the joys...
 

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Discussion Starter #6
Even a failed fuel pump wouldn't generate any fault code. But the fact that you are getting whole bunch of other codes tells me that your focus should also be toward other areas besides the pump. I would also check the MAF and see if that's working in the spec range since you are reporting air flow fault code (just a thought).
Hey! Thanks for the input!

I didn't think there was any fuel pump monitoring, but I wasn't sure with a Passat. None of the other faults I found with VCDS were in engine blocks, so I don't think they would prevent starting. They were mostly for the air conditioning system(air direction/blend door from the climate control). Now, I understand that I may be wrong, so if you know differently, I'm open to learn for sure. So, will hvac interior items throw an EPC? I honestly don't know. I did unplug the MAF and plugged it back in to try to verify connections, but I did not try to start the car with the MAF unplugged. All air flow faults were for the A/C system.
 

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Discussion Starter #7
It just occurred to me, since you have VCDS...

You can look at the engine speed in the ECM measuring blocks to immediately know if the ESS is working.
Will the ESS signal show up in VCDS during cranking? The car doesn't need to be running? I'll have to try to find out which measuring block that's in.
 

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The ESS can throw a code, but (frustratingly) it usually doesn't. The ECM doesn't have anything reliable to compare it with, so it seldom "knows" it's signal is missing.

I believe the EPC light comes on (like Check Engine, etc) when you turn the key to on, so it being on when the engine is not running isn't remarkable (particularly when observed by non-car people).

I would certainly expect to see an ESS signal during cranking--the ECM has to see it before fires the injectors and coils. The measuring blocks are just a window in to the ECM.

I do agree regarding the other codes--there's nothing there that would prevent starting. To quote many a fine mechanic on this forum: "fuel and spark."
 

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Car turns over but does not start...
Monitor the engine RPM, sensor G28, in the ECM measuring blocks while cranking (it's one of the low numbered blocks). You should see an engine RPM while cranking, even if doesn't fire. The ECM requires a signal from G28 before it fires the injectors and coils. If you never see an RPM, your ESS isn't working.
 

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Discussion Starter #11
Great responses! I appreciate them! I am not sure when I will be able to lay hands on the car again, but I will look at the measuring blocks for signs of the ESS signal.

Another question … in regard to the suggestion above about cranking for longer than 5 seconds … Can anyone tell me if that bypasses any and every ESS signal? To clarify my question: If the ESS were to be the only problem that was preventing starting, cranking longer than 5 seconds will allow it to start? If I cut the ESS cable completely in two(not that I would of course), would it still start and run(like in closed loop) if the ESS were the only faulty item? I'm trying to gather my thoughts on where to go next if the car still does not start. Once again, if nothing else were wrong with any Passat in this year range, could I disconnect the ESS completely and perform the extended cranking and expect it to start? Or will the extended cranking only ignore 'out of range' readings but still require a signal from the ESS? I don't know if I'm asking my question right or not...haha. Maybe you know what I mean. I will not be the one performing the extended cranking, so I want to have an idea of what the results mean when I receive his feedback. Thanks again!!!
 

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If the ESS is working, you should see the rpm move when cranking. The V6 is also very prone to flooding, so if the car was moved a short distance and parked, it could simply be flooded. I know the FWD 2003 models had issues with failing fuel pumps, but I don't know if that carried over to the 4Mo models. Ignore any single interior codes, multiple codes may indicate a problem with the CCM which could cause starting problems, but usually it would not crank.
 

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Another question … in regard to the suggestion above about cranking for longer than 5 seconds … Can anyone tell me if that bypasses any and every ESS signal? To clarify my question: If the ESS were to be the only problem that was preventing starting, cranking longer than 5 seconds will allow it to start?
It will definitely start and run. The EPC light will be on and the idle will be high (~1000 RPM), but otherwise normal. I drove my Fresco Green 2001.5 1.8T home from work that way several years ago.
 

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Discussion Starter #14
Got a report back last night that the needle on the tach does raise a little during cranking, so I'm going to assume the ESS is reading. I've told him how to find and remove the fuel pump cover plate and how to use a test light to see if the pump is being told to run when the driver's door opens or when the key is cycled by reading across the two outer leads in the pump connector. I don't know if he'll be able to get the plate off...or the ''VW special'' electrical connector. I'm waiting to hear back from him. Oddly enough, I just(yesterday) had to replace the fuel pump in my 01' VR6 Jetta. Exact same symptoms in every way. Strange huh?
 

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Check the voltage at fuse 28 (With fuse connected) while cranking.
If the voltage is not above 9v, the problem is not the fuel pump.

If the FP relay is activated during cranking and the voltage at fuse 28 is not above 9V, the relay is probably faulty.
If the FP relay is not activated during cranking, check the ignition switch T15 (Should be 12V when on or start position)
 

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Discussion Starter #16
Sorry for the delayed response. Updated information shows that it was indeed the fuel pump. He took it to a shop and they charged him $695! I could have done that job in 15 minutes...ugh. Oh well, at least my guess was correct. Thanks to you all for offering information!!!
 
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