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Discussion Starter · #1 ·
I have a 2004 2.5 TDI Touareg auto with 124,800 miles on the clock.

A short while ago the PNDRS panel on the dash stayed lit instead of indicating the operating gear. The car drove perfectly normally so I ignored it as a service was soon due and garage could sort it out then. However, after it had been in very hot sun I tried to start it but the ESP light stayed on also and it made no attempt to start. I was 150 miles from home so called for breakdown assistance. Mechanic plugged in his kit and said it was a TCM issue. No power being allowed to the starter. Several hours later a breakdown truck arrived. He was about to winch it onto his lorry in PARK so I stopped him and turned on the ignition in order to get it into Neutral. Must have been a bit heavy on the ignition switch as the car suddenly burst into life. The ESP lit had gone off allowing it to start. Drove home with no problem. Parked up, switched off. Then tried another start. Nothing - the ESP combination of warning lights were back.

Next day. Car started with PNDRS only lit up. Drove to my normal (non-VAG) garage. They spent several hours trying to find the fault but said I would need to go to the main agents. They found faults relating to intermittent communication between ECU and ABS. They said that when they cleared the faults the car would start and drive perfectly but the faults simply reappeared. As the car is 2004 it is not cost-effective to go to my main VW agents. Made this mistake before. So thought I would ask if anyone else had come across this problem. I know that the Forum techies will want proper fault codes so today I had a mobile diagnostic chap with a Ross-Tech VCDS come to me to check out the fault codes.

So here goes:

Address 03: ABS Brakes Labels: 7L0-907-379-MK25.lbl
1 Fault found:
01314 - Engine Control Module
004 - No Signal\Communication

Address 05: Acc\Start Auth. Labels: 3D0-909-13x-05.lbl
3 Faults Found:
01049 - Supply Voltage Term 50
009 - Open or Short to Ground - Intermittent
01314 - Engine Control Module
004 - No Signal\Communication
01299 - Diagnostic Interface for Data Bus (J533)
013 - Check DTC Memory

Well Guys is this enough for you to point me (or auto electrician really) in the right direction. At the moment I am contemplating selling the car as spares or repair because I cannot afford to put it through the main agents to learn on. As the Engineer who came today said - it would be a shame because it is a really nice car and it is probably just a poor connection somewhere.

Advice please
Thanks in anticipation.
 

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To begin with I would lift the front passenger carpet and check for evidence of dampness. Check electrical harness near the base of the A pillar, peel back insulation and examine all wiring splices for corrosion.
 

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Discussion Starter · #3 ·
To begin with I would lift the front passenger carpet and check for evidence of dampness. Check electrical harness near the base of the A pillar, peel back insulation and examine all wiring splices for corrosion.
Thank you Chaser for your early response. I popped out last night to do as you say, only to find that lifting the carpet is not a straight-forward job. Presumably the insert part of the trim over the sill hides some hex screws. I will need to investigate this further during the week when the weather is fine. The beast is outside on my drive. I am expecting it to be dry as I have had no hint of dampness or condensation in the cabin, but we will see.... Again thanks
 

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Discussion Starter · #5 ·

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Eh?

Not sure you read my post aright: the wiring and the battery are on the same side of the car regardless of where the steering wheel is, i.e., both on the right when looking at the car from the front.
 

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Eh?

Not sure you read my post aright: the wiring and the battery are on the same side of the car regardless of where the steering wheel is, i.e., both on the right when looking at the car from the front.
I must have had my glasses on back to front, yes that makes sense.

J
 

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Thank you Chaser for your early response. I popped out last night to do as you say, only to find that lifting the carpet is not a straight-forward job. Presumably the insert part of the trim over the sill hides some hex screws. I will need to investigate this further during the week when the weather is fine. The beast is outside on my drive. I am expecting it to be dry as I have had no hint of dampness or condensation in the cabin, but we will see.... Again thanks
Had another look under the front carpet after part removing the sill plastic trim. I can see and feel the wiring loom and the metal floor under. They are both 'dry as a bone' and the floor is sparkling new with absolutely no sign of damp. I am reluctant to proceed with the seats and carpet out process so as to cut open the loom given it's seemingly good condition.

Further advice please gentlemen.

Oh... and to add insult to injury the car started today, and then restarted without the ESP light lit. But I know it is only tempting me to begin using it again so it can wait until I am miles from home again before failing again.
 

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Discussion Starter · #10 ·
To begin with I would lift the front passenger carpet and check for evidence of dampness. Check electrical harness near the base of the A pillar, peel back insulation and examine all wiring splices for corrosion.
Whilst awaiting delivery of a spline to lift the front seat to better check the condition of the passenger side foot-well loom, I have been regularly checking the the times at which the car will start.

Yesterday at 12.30pm (Hot day) only the PNDRS fault was showing (without the ESP warning lit) and the car started. Flushed with success I took it for a 20 mile drive to test whether everything worked as it should; it did. Pleasure to drive again. But on return switched off, and tried again. This time (as expected) PNDRS and ESP lit so will not start. Tried again at 3.00pm (Hot day still) and just PNDRS lit on; Will now start. 4.30pm (very hot in sun) and 6.00pm (now cooler); PNDRS and ESP lit so will not start. What I did notice is that upon switching ignition on, there is a 'click' from under the car as the ESP warning lights up on the dash. Seems to come from Left hand side (under driver on LHD) but cannot check it until I can muster another pair of hands. Could this be the Starter Solenoid at fault? The problem seems to manifest itself when car is hot either after running or when out in sun.

Today at 7.30am (nice day but car cool) just PNDRS lit on; Will now start. It is likely to be hot again today (YES really in UK) so will check throughout the day and log.

Any thoughts Chaser or NobbyT?
 

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Thoughts.....

you need an electrician armed with circuit diagrams...

the starter is on the right side.... you could be hearing a relay clicking, there are some under the passenger seat and also in an electronics box in the left plenum.

the various errors will almost certainly linked to one fault, possibly resulting in a control unit losing power so cannot communicate with other control units...therefore multiple errors. hence mentioning the fairly common issue of harness corrosion.

once you have the seat tilted back check everything from battery connections, earth points, to engine compartment starting aid connection, to alternator and on to engine control unit and its connections fitted in right plenum also abs controller below it.
 

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Discussion Starter · #12 ·
Thoughts.....

you need an electrician armed with circuit diagrams...

the starter is on the right side.... you could be hearing a relay clicking, there are some under the passenger seat and also in an electronics box in the left plenum.

the various errors will almost certainly linked to one fault, possibly resulting in a control unit losing power so cannot communicate with other control units...therefore multiple errors. hence mentioning the fairly common issue of harness corrosion.

once you have the seat tilted back check everything from battery connections, earth points, to engine compartment starting aid connection, to alternator and on to engine control unit and its connections fitted in right plenum also abs controller below it.
Thanks Chaser
I have today had managed to tilt the seat and lift the front passenger carpet. All good under there. Amazed to see everything clean and shiny like new. Earth good and no damp or rust. Opened up part of the loom and again no damp or evidence of such in the past. All like new. So have re-taped loom and put all back.

My log for today's starting potential (ambient temp. in brackets) is as follows:

07.30 (Cool) - Only PNDRS panel lit. Car would start if requested.
10.00 (Warm)- Only PNDRS panel lit. Car would start if requested.
12.00 (Quite Hot)- ESP + PNDRS panel lit. No chance of start.
14.30 (Hot)- ESP + PNDRS panel lit. No chance of start.
16.30 (Quite Hot)- ESP + PNDRS panel lit. No chance of start.
18.00 (Warm)- ESP + PNDRS panel lit. No chance of start.
22.00 (Cool) - Only PNDRS panel lit. Car would start if requested.

I think that the ambient temp prior to starting is relevant and more than co-incidental.

I downloaded the VW Self-study Programme 298 'The Touareg Electrical System'. On Page 17 it indicates that there is a C20 'Terminal 50 Power Supply' Relay in the Plenum Chamber box. I was interested in this relay as one of the faults recorded by Ross-Tech was 01049 'Supply Voltage Terminal 50'. However when I opened up my plenum box there was no C20 Relay. Unfortunately it appears that Fuses and Relay positions vary according to model and engine type. The tutorial refers the reader to ELSA (electronic service information system).

So stumped again
 

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If your spanner skills are good, then do look at ELSA.

You can buy time on there by the hour or day, and download what you need.
 

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Discussion Starter · #14 ·
If your spanner skills are good, then do look at ELSA.

You can buy time on there by the hour or day, and download what you need.
Thanks NoobyT
Didn't realise I could buy time with ELSA (so to speak!). Will investigate.
 

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LOL, spanner skills are of no help when it comes to modern vehicle electronics. A 20 something with computer skills probably has a better chance of understanding and tracing this stuff.

VCDS scans can help but often only if you can use the time stamps and other recorded information to fathom "chicken and egg" situations. Consequential errors can send you looking in the wrong place. There are almost always red herrings in scan reports. In my experience you also have to clear codes regularly during fault finding because every time you remove a connection, fuse or component to inspect it, that flags further codes.

As for the temperature influence, sometimes a faulty starter motor will refuse to operate when it's hot. I don't think it would throw these codes you have reported though.
Resistance would increase with temperature in any poor electrical connection in a circuit would it not so logging temps isn't necessarily telling you anything new.

You might be better passing this up and employing the services of a VAG experienced auto electrician. Without diagnostics equipment at hand to aid you and experience at deciphering the current flow diagrams the odds are against most diy'ers.
 
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Discussion Starter · #16 ·
LOL, spanner skills are of no help when it comes to modern vehicle electronics. A 20 something with computer skills probably has a better chance of understanding and tracing this stuff.

VCDS scans can help but often only if you can use the time stamps and other recorded information to fathom "chicken and egg" situations. Consequential errors can send you looking in the wrong place. There are almost always red herrings in scan reports. In my experience you also have to clear codes regularly during fault finding because every time you remove a connection, fuse or component to inspect it, that flags further codes.

As for the temperature influence, sometimes a faulty starter motor will refuse to operate when it's hot. I don't think it would throw these codes you have reported though.
Resistance would increase with temperature in any poor electrical connection in a circuit would it not so logging temps isn't necessarily telling you anything new.

You might be better passing this up and employing the services of a VAG experienced auto electrician. Without diagnostics equipment at hand to aid you and experience at deciphering the current flow diagrams the odds are against most diy'ers.
Finally frustration got the better of me. Put it up on Ebay as Spares or Repair. Lot of interest - 20 Offers in 24 hours. Sold with 48 hours to a large used spares company in Braintree. My Touareg may live on by supplying Treg Owners with transplanted parts.

So I guess this is my Goodbye. Thanks for all your help over the last few years.

Regards Lovejoy
 

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Finally frustration got the better of me. Put it up on Ebay as Spares or Repair. Lot of interest - 20 Offers in 24 hours. Sold with 48 hours to a large used spares company in Braintree. My Touareg may live on by supplying Treg Owners with transplanted parts.

So I guess this is my Goodbye. Thanks for all your help over the last few years.

Regards Lovejoy
That was a pretty drastic measure....was it not worth getting a decent sparky to look at it first?
 

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Just replying here in case it helps anyone else. I have an almost identical issue (ESP light, PRNDS flashing, loss of power, intermittently not starting) on a 2007 Skoda Octavia mk2 1.9 TDI DSG. The ESP does seem to be the key reason for not starting/engine cutting out while driving, as it has started with PRNDS flashing. The garage has changed the relay however this hasn’t fixed the issue. The error code 01314 (loss of signal to the electrical control box - ECU) has come up on the the garage diagnostics (non VAG) under the heading ‘Brake Electronics’. After lots of searching online I’m thinking this is related to the ABS wheel speed sensors rather than the ECU itself however I am by no means an expert. I am heading back to the garage when it reopens to see if these can be replaced. I’ll keep you all posted on progress!
 

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I had a similar issue on my Treg and the final result was water in the heater controls, which was causing all kinds of silly backfeed problems in the electrical system, I had esp, and general electrical faults turning up in all systems
Problem is that each of the various electrical systems 'talk' to each other through the canbus and if there is a fault or failure, it is like a domino effect
 
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