'09 Touareg 3.0 TDI sudden limp mode, man code. Help please.

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Jack@European_Parts

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Take plug off of ecu and identify the track you wish to investigate with WD, then remove connector to isolate, further now test the 5 volt ref at controller directly.
Make double sure all power feeds/grounds or fuses are good!
Do not perform tasks if you feel you are unsure of the scope of the project & to prevent inducing damage.
 
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MmmBoost

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Take plug off of ecu and identify the track you wish to investigate with WD, then remove connector to isolate, further now test the 5 volt ref at controller directly.
Make double sure all power feeds/grounds or fuses are good!
Do not perform tasks if you feel you are unsure of the scope of the project & to prevent inducing damage.

Jack,

I've done all the testing I think I'm capable of doing with the tools/knowledge/skills I have. I'm at the point now where I'm 90% sure it's the ECM that died. The scariest part is that I don't know what caused it to go. I'm pretty close to taking it to the dealership, telling them all I've done to try and figure out and let them take it from there. I hate the dealership.....and I don't trust them, but at the end of the day, if they don't fix the problem properly and it nukes another ECM......it's all on them, not on me. My vehicle has been down for 2 weeks now and I've already thrown an AdBlue pump at it for no reason. I need my vehicle running again and I need reassurance that it's FIXED.

I can't de-pin the ECM because I don't have the tools to do so, but I tested the 5V line at both the g686 and J724 and neither are giving 5V. I even tested them to chassis ground and still not getting a correct value, so there is something fubar'd in the ECM on the 5V ref circuit.

All of the diagnostics say that if you don't get the right initial value, test for continuity. If you get continuity.....clear the DTCs and drive it. If they come back.......replace the J623. *sigh*
 
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Jack@European_Parts

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I can't de-pin the ECM because I don't have the tools to do so, but I tested the 5V line at both the g686 and J724 and neither are giving 5V

So seriously you don't have a dental pick and dykes to cut a tie wrap?

How hard is it to trace & cut one wire directly at the ecu then insert a dead pin with wire attached to measure with DVOM from an open bay?

You are letting something simple really seem complex when it isn't.

Read this thread below and the RTFB how to take an ecu plug apart or YouTube a video.

http://forums.ross-tech.com/showthread.php?7877-VAG-crimp-tools&p=102610&viewfull=1#post102610


You have done far more technical tests than this already .............as much as I like your hedge idea to go play dealer fiddle fuck to pass the liability ball, you negated the fuse idea I posed earlier & for each shared track to protect a future ECU.



All of the diagnostics say that if you don't get the right initial value, test for continuity. If you get continuity.....clear the DTCs and drive it. If they come back.......replace the J623. *sigh*
WTF........in a whisper......

 
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MmmBoost

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So seriously you don't have a dental pick and dykes to cut a tie wrap?

How hard is it to trace & cut one wire directly at the ecu then insert a dead pin with wire attached to measure with DVOM from an open bay?

You are letting something simple really seem complex when it isn't.

Read this thread below and the RTFB how to take an ecu plug apart or YouTube a video.

http://forums.ross-tech.com/showthread.php?7877-VAG-crimp-tools&p=102610&viewfull=1#post102610


You have done far more technical tests than this already .............as much as I like your hedge idea to go play dealer fiddle fuck to pass the liability ball, you negated the fuse idea I posed earlier & for each shared track to protect a future ECU.

WTF........in a whisper......


Looking at that connector it looks like a giant expensive accident waiting to happen. De-pinning deutsche connectors is a giant pain in the ass without the right tools......I've done it many times before. Most of the time the ends get pretty mangled and I was afraid of screwing up my wiring harness.

I didn't negate your fuse idea. I like the idea it's just not part of finding out what's wrong so I wasn't focusing on that. Putting fuses inline is all well and good but I don't even know what I need to fuse. I have no idea what caused the malfunction in the ECU...



I'll go take another look at that connector and see what I can do........ Don't get frustrated with me. You deal with this stuff on a daily basis and have tons of experience. Fixing a leaking oil line is one things because I can see the oil leaking out..... fixing a leaking wire is a whole other ball game.
 
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Jack@European_Parts

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Looking at that connector it looks like a giant expensive accident waiting to happen. De-pinning deutsche connectors is a giant pain in the ass without the right tools......I've done it many times before. Most of the time the ends get pretty mangled and I was afraid of screwing up my wiring harness.

I didn't negate your fuse idea. I like the idea it's just not part of finding out what's wrong so I wasn't focusing on that. Putting fuses inline is all well and good but I don't even know what I need to fuse. I have no idea what caused the malfunction in the ECU...



I'll go take another look at that connector and see what I can do........ Don't get frustrated with me. You deal with this stuff on a daily basis and have tons of experience. Fixing a leaking oil line is one things because I can see the oil leaking out..... fixing a leaking wire is a whole other ball game.


Not frustrated ........I'm having fun :rolleyes:

The fuse idea will indeed find the problem area when a sporadic issue arises or the blind like yourself.................:p

Jack makes special tools...........he has way to much time to think up this shit!

Takes old ecu's and then extracts the receptacle by de-solder then installs a breakout fuse box in between all tracks.........then with a new pigtail from the dump on the other side pin for pin to plug into the ecu

The fuses he uses have LED's when they pop.

It is a very useful tool for lemon cars he deploys.

Seriously, the ecu connector is the easiest connector on the car to deal with now......& over sensors I think for simple tools such as a pick.

VAG1598 can kiss NostraJackAss's Ass
 
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MmmBoost

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OK Jack... I went back out there and took apart the T94 connector, thanks for the kick in the ass. I popped the 17 pin out of the harness and inserted a piece of wire. Test voltage from the T94/17 to chassis and was only seeing .64V which is roughly what I was seeing at J724 and G686 at their respective 5V pins on the connectors. So it is 100% the ECU not putting out the correct 5V Ref voltage to the modules/sensors.

So basically with the fuses you're saying don't bother figuring out which circuit caused the issue, just fuse them in case it happens again and that'll give me my answer? Should I be fusing the 5V wire only or the signal wire are well. At this point its difficult for me to figure out what caused the issue. The AdBlue heater tested out fine and so did the wiring. What's the likelihood that the ECU decided to just up and die? Seems unlikely on modern solid-state electronics.


Also I was curious if I should be worried about all the "malfunction 0010" codes I saw from my initial scan. Like the CAN Gateway......but the actual scan of the module showed no faults.
 
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Jack@European_Parts

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Yup fuse all related tracks or sensors to tracks that could of internally shorted even when they dont cross but share a destination. Use the lowest amp fuse possible.
 
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MmmBoost

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Hi Gentlemen. So I'm bringing this thread back from the dead....

I ran out of time trying to sort out my Touareg on my own and had it towed to the dealership to be repaired. (it sucks.....$$$$......but at least there will be warranty coverage on their work). They ended up replacing the ECM and said "it's all fixed." When I asked them if they figured out what caused the ECM to fail, they said....."....The ECM died so we replaced it, all the codes went away." Well 4 days later I was left stranded in limp mode again after leaving work. No warning.....exactly like the last time. They've now had my vehicle back in their shop since mid-september and have escalated the issue with VW engineering and have involved their regional TQM (technical quality manager) into things because they've run out of places to look. Unfortunately with this guy involved, things are taking FOREVER to get fixed.

So far they have replaced the ECM again (at their cost), and I guess are still getting a code for 5V reference issue. I'm waiting for a call from the shop foreman in order to have an actual technical discussion with him and possibly get actual DTC's out of him. When they replaced the ECM the first time, I assume there were no codes present in the vehicle before giving it back to me which would assume there was no pre-existing indication something else was wrong. So what I don't understand is why there is a code present now on the replacement ECM.

The non-technical service person told me was they think they had narrowed it down to the Throttle Valve Control Module J338. She said when they unplug the connector at the throttle body, they were not able to clear the code for the 5V reference DTC so she asked me to authorize the replacement of the connectors and wiring for it. I said yes. She called back a few hours later telling me that the problem was still present. So the TQM advised the next step is to replace the throttle body..... for $958. There's never been a code for the throttle body.....I don't understand how this is suddenly what the problem is. Why wouldn't it be any one of the DOZENS of sensors that use 5V? Why would the code not have gone away after they replaced the wiring and clearing the DTCs with the connector still disconnected if the wiring/connector was the issue?? Honestly I'm at my end of my patience with them right now and I don't want them to just start throwing parts at the vehicle hoping something fixes it.

I realize without the codes that are still present it's difficult to offer input, but does anyone have any theories as to what the hell is going on with my Touareg or where I might direct the "professionals" to look next?


The codes that I was getting when this all started were:
001617 - Sensor Reference Voltage B
P0651 - 000 - Open Circuit - MIL ON
001617 - Sensor Reference Voltage B
P0651 - 000 - Open Circuit - MIL ON
008487 - Accelerator Position Sensor 2 (G185)
P2127 - 000 - Signal too Low - MIL ON


The only thing that these 2 sensors share in common is that they both use a 5V reference signal. Neither sensor shares any connections outside of the ECM. I can't understand how 2 separate circuits were both malfunctioning separately and with different codes. One says open circuit and the other said signal too low. Is it possible that it's something as simple/stupid/easy-to-overlook as a bad battery?


Also I felt like I should mention.....both times that I hit limp mode were within 5-6 minutes of starting my Touareg and driving away.
 
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   #29  

MmmBoost

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I spoke with the shop manager this morning to get a more accurate description of what's going on. They are still doing all of the wiring/diagnostics on the 1st replacement ECU which doesn't give me a lot of confidence considering I'm pretty sure it's fucked like the original ECM. He explained to me that the TQM advised them to de-pin each wire 1 at a time on the G686 Pressure sensor, the G185 Accelerator Pedal, and the J338 Throttle Valve Control Module.....and then clear the codes, observe the results. From what he tells me, the J338 is the only module/sensor which didn't register any new DTCs.....so the TQM is pretty sure this is where the problem lies. As I mentioned above, new wiring/connectors to the J338 did not fix the issue.

Honestly I don't really see what there is to go wrong in the throttle body..... all it has in it is 2 potentiometers and a servo motor. When asked if the J338 was giving proper values in the ECM (as is the first test in the diagnostic procedure) he said he wasn't sure and he'd have to check. I'm hoping that he just didn't know because the tech did this work.

Has anyone seen issues like mine come from a throttle body or a throttle pedal? From what I'm told the wiring for the ECM has been inspected thoroughly visually and with a meter. Basically the shop has no idea where to go next and I just want my damn vehicle back. Can anyone please chime in here?
 
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