Towbar installation: would a period harness fit ?

NicM

NicM

Member
France
I've just sourced an OEM Alko 8Z0 092 155 towbar at a scrapeyard an hour away (the first I've seen pop up in the whole country for about half year that I've been monitoring ads - this was on an impounded 1.4 diesel, probably not factory installed): not quite complete but not apparently corroded (I'll probably have to make the two riveted tube holders at the front). I've ordered the missing keys from the UK based on the engraved hitch lock number (key2code, no affiliation on my part), and am now looking for the best cost effective solution for a 13 pin harness.
What I gather from the forum is the ERICH JAEGER 748972 kit would be the prefered choice, though I've only seen a couple for sale in Germany at a price largely exceeding that of the mechanical part... I've seen on a German forum someone using a 8Z0055204 harness, which sparked me the following question: what would be the requirements/pitfalls to avoid for fitting/adapting a period harness from a more commonly available car (e.g. A3 8L 8L0055204D)?
My car was built in Oct. 2002 as per the options list tag (#17677)
 

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Check schematics in ELSA. I suppose wiring could be made from scrach even without donor loom.
 
3dB said:
Check schematics in ELSA. I suppose wiring could be made from scrach even without donor loom.
Click to expand...
thank you for your reply - I don't know about ELSA though... I suppose I'll need an upgrade about that, too.

The possibility of "wiring from scratch" the old way or the use/necessity of a decoupling setup of sort is part of the question I was wondering about (also avoiding butchering the original harness if at all possible - though I'm not sure about specific connectors requirement to do a clean job)...
 
Are you looking for just rear lights, stop, tail and fog plus indicators, or do you want power too, as in a caravan?
Mac.
 
PlasticMac said:
Are you looking for just rear lights, stop, tail and fog plus indicators, or do you want power too, as in a caravan?
Mac.
Click to expand...
as far as functionnality goes the minimum you mentionned would probably do (in "modern" 13 pin version for cross compatibility just in case), but if at all possible I'd like to do a clean, efficient installation (i.e. if a fully functionnality is reachable I would go the extra mile). Most important would be a smooth integration within the car, which I'm beginning to fear as it's not clear yet who is the master (by way of recurring EML of late)...
 
Personally, and just my opinion, I'd fit a proprietary 7 way relay box, (circa £15 in UK), and tee into the brake, right and left tail, rear fog, left and right indicator feeds, (and reverse light if required), plus the battery, via a 15 amp inline fuse. You'll need the schematic to identify the wire colour code for each lamp, and tee into them close to each rear light cluster.
I've looked through the schematics, and can't find any reference to tow bar wiring.
(There is a trailer led in the instrument cluster, but it's not connected to the outside world).
On the 13 pin socket, the unused pins, for trailer battery charging etc, will be left unused in a basic trailer configuration.
With the battery in the boot, picking up the supply is easy.
Looms from other cars of the period, cars which were intended to tow, will, probably, include connection to the ESP/CANBUS system to modify operation when a trailer is attached, but I can't find any indication that this is the case on the A2, but I could be wrong, if so, someone will correct me, no doubt.
In the UK, the 7 pin trailer socket is still commonly used, but in the rest of Europe, the, (superior), 13 pin Jaeger has been standard for years.
Mac.
 
bretti_kivi said:
Check control will be the difficult bit. Your A2 has DIS/FIS?
Click to expand...
I must admit my ignorance (car still in test mode as not deemed reliable for recurring EML, I have not tried it much yet), will be looking into the DIS versions next time I'll go to where it's stored (not sure what FIS would be :oops:).
 
NicM said:
I must admit my ignorance (car still in test mode as not deemed reliable for recurring EML, I have not tried it much yet), will be looking into the DIS versions next time I'll go to where it's stored (not sure what FIS would be :oops:).
Click to expand...
You need a scan to diagnose the cause of the EML.
Using the 7 way relay box for the tow bar wiring, means that the DIS, (the display in the centre of the dash cluster, of which there are two variants, basic and full), has no involvement at all.
The relay box provides complete electrical isolation from the car's systems.
Mac.
 
PlasticMac said:
You need a scan to diagnose the cause of the EML.
Using the 7 way relay box for the tow bar wiring, means that the DIS, (the display in the centre of the dash cluster, of which there are two variants, basic and full), has no involvement at all.
The relay box provides complete electrical isolation from the car's systems.
Mac.
Click to expand...
If you decide to go ahead with the towbar, let me know, and I'll PM you more detailed information.
Mac.
 
PlasticMac said:
If you decide to go ahead with the towbar, let me know, and I'll PM you more detailed information.
Mac.
Click to expand...
much appreciated ! I certainly can make good use of any information as I'm discovering the A2 field... I'm definitely set to install the towbar as this was one of the arguments for the purchase earlier this year, being able to tow more than with my current daily (Citroën Ax), and 1000kg capacity is just perfect with a light trailer (I love aluminium). I've ordered the A3 8L harness (NOS but cheap enough) and will give it a go in August upon kit content examination.

As for the EML I'm also starting on the (steep) learning curve with VCDS, will try to calibrate the FSI flaps (throttle body too probably) next time I'll go to the storage as the car has started doing just recently after I tried a carbon deposit cleaner on the EGR (spray, not the full monty inlet out procedure just yet) ... I then changed the N316 (Pierburg) valve as it was easy enough but no joy (there was vaccuun on it when it took it out). Defaults would vary but this is what I got recently (the vacuum leak bit is not systematic)

Address 01: Engine Labels: 036-906-013-BAD.lbl
Part No: 036 906 013 F
Component: MED7.5.11 G 4628
Coding: 00051

5 Faults Found:
17852 - Potentiometer for EGR (G212)
P1444 - 35-00 - Implausible Signal
17439 - Intake Manifold Tuning Valve (N316)
P1031 - 35-00 - Setpoint Not Reached
18322 - Pressure Sensor for Brake Boost (G294)
P1914 - 35-00 - Implausible Signal
17912 - Intake Air System
P1504 - 35-10 - Leak Detected - Intermittent
16787 - EGR Valve (N18)
P0403 - 35-00 - Malfunction
Readiness: 1110 0001

I was still trying to make sure there are no coolant leaks before accumulating some mileage in spite of the EGR (I've found out the oil pressure sensor is seeping through so ordered a new one), but then the kangaroo throttle hit (I suspect FSI flap because this is between 2000 and 3500 rpm and after the engine warms up a bit - I wonder if there is a way to tweak the tune with VCDS to make sure though)...
 
NicM said:
much appreciated ! I certainly can make good use of any information as I'm discovering the A2 field... I'm definitely set to install the towbar as this was one of the arguments for the purchase earlier this year, being able to tow more than with my current daily (Citroën Ax), and 1000kg capacity is just perfect with a light trailer (I love aluminium). I've ordered the A3 8L harness (NOS but cheap enough) and will give it a go in August upon kit content examination.

As for the EML I'm also starting on the (steep) learning curve with VCDS, will try to calibrate the FSI flaps (throttle body too probably) next time I'll go to the storage as the car has started doing just recently after I tried a carbon deposit cleaner on the EGR (spray, not the full monty inlet out procedure just yet) ... I then changed the N316 (Pierburg) valve as it was easy enough but no joy (there was vaccuun on it when it took it out). Defaults would vary but this is what I got recently (the vacuum leak bit is not systematic)

Address 01: Engine Labels: 036-906-013-BAD.lbl
Part No: 036 906 013 F
Component: MED7.5.11 G 4628
Coding: 00051

5 Faults Found:
17852 - Potentiometer for EGR (G212)
P1444 - 35-00 - Implausible Signal
17439 - Intake Manifold Tuning Valve (N316)
P1031 - 35-00 - Setpoint Not Reached
18322 - Pressure Sensor for Brake Boost (G294)
P1914 - 35-00 - Implausible Signal
17912 - Intake Air System
P1504 - 35-10 - Leak Detected - Intermittent
16787 - EGR Valve (N18)
P0403 - 35-00 - Malfunction
Readiness: 1110 0001

I was still trying to make sure there are no coolant leaks before accumulating some mileage in spite of the EGR (I've found out the oil pressure sensor is seeping through so ordered a new one), but then the kangaroo throttle hit (I suspect FSI flap because this is between 2000 and 3500 rpm and after the engine warms up a bit - I wonder if there is a way to tweak the tune with VCDS to make sure though)...
Click to expand...
Good Afternoon,

On the flap front from my experience the flap movement (or not) is not particularly noticeable when driving. However the fault codes are pointing at stuck flaps and I suggest you log and post here measurement block 142. Ten seconds will do for a start maybe best with warm engine, start log, start engine, idle for a few seconds and then a heavy rev >3000, let revs return to idle and end log.

Andy
 
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NicM said:
much appreciated ! I certainly can make good use of any information as I'm discovering the A2 field... I'm definitely set to install the towbar as this was one of the arguments for the purchase earlier this year, being able to tow more than with my current daily (Citroën Ax), and 1000kg capacity is just perfect with a light trailer (I love aluminium). I've ordered the A3 8L harness (NOS but cheap enough) and will give it a go in August upon kit content examination.

As for the EML I'm also starting on the (steep) learning curve with VCDS, will try to calibrate the FSI flaps (throttle body too probably) next time I'll go to the storage as the car has started doing just recently after I tried a carbon deposit cleaner on the EGR (spray, not the full monty inlet out procedure just yet) ... I then changed the N316 (Pierburg) valve as it was easy enough but no joy (there was vaccuun on it when it took it out). Defaults would vary but this is what I got recently (the vacuum leak bit is not systematic)

Address 01: Engine Labels: 036-906-013-BAD.lbl
Part No: 036 906 013 F
Component: MED7.5.11 G 4628
Coding: 00051

5 Faults Found:
17852 - Potentiometer for EGR (G212)
P1444 - 35-00 - Implausible Signal
17439 - Intake Manifold Tuning Valve (N316)
P1031 - 35-00 - Setpoint Not Reached
18322 - Pressure Sensor for Brake Boost (G294)
P1914 - 35-00 - Implausible Signal
17912 - Intake Air System
P1504 - 35-10 - Leak Detected - Intermittent
16787 - EGR Valve (N18)
P0403 - 35-00 - Malfunction
Readiness: 1110 0001

I was still trying to make sure there are no coolant leaks before accumulating some mileage in spite of the EGR (I've found out the oil pressure sensor is seeping through so ordered a new one), but then the kangaroo throttle hit (I suspect FSI flap because this is between 2000 and 3500 rpm and after the engine warms up a bit - I wonder if there is a way to tweak the tune with VCDS to make sure though)...
Click to expand...
Clear the DTCs before worrying. They, or at least some of them, may well be historical, and once cleared, wil stay clear. Once cleared,go for a varied drive, making sure you use 3,500 rpm a few times, (to exercise this inlet flaps), and a bit of load, to tax fuel pump etc. Then scan again.
Mac.
 
PlasticMac said:
Clear the DTCs before worrying. They, or at least some of them, may well be historical, and once cleared, wil stay clear. Once cleared,go for a varied drive, making sure you use 3,500 rpm a few times, (to exercise this inlet flaps), and a bit of load, to tax fuel pump etc. Then scan again.
Mac.
Click to expand...
I've already covered about 100km, including some very pleasant highway test (I've been fixing it for some months now, on and off, mostly off) and I've cleared the DTC several times - EML was sometimes coming back not immediately (after a few power offs?) - I was about to try it further when this "kangaroo" throttle came up, right after the spray cleaning of the EGR valve, and it makes the car less driveable. As the saying goes here, better is worse than good, I suppose I should have gone the hard way and take the inlet manifold out to be sure, but did not want to embark in that risky procedure (for the injectors?) if not absolutely necessary... I'm planning one trip there this week if I get the spare oil pressure sensor and will do some VCDS tests, then I'll have time in August to work on it.
I was hoping that there may be a test procedure to "exercise" the flaps without the engine on, so that I can stand in front of it and watch how it goes...
 
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Attached oem wiring diagram for trailer socket from model year 2003.

It seems to me there is no quick plug & play tow harness connection possible, no empty connectors etc. Easiest route would be to splice in any existing wiring not rip apart half a car to put in one with correct extras for your car. It's just 7 or 13 wires, depending on connector.

Mine A2 has a towing bracket installed from factory with full FIS autocheck etc, but unfortunately I don't have towing hook as it's removable, so it's a complete waste on mine.
 

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3dB said:
Attached oem wiring diagram for trailer socket from model year 2003.

It seems to me there is no quick plug & play tow harness connection possible, no empty connectors etc. Easiest route would be to splice in any existing wiring not rip apart half a car to put in one with correct extras for your car. It's just 7 or 13 wires, depending on connector.

Mine A2 has a towing bracket installed from factory with full FIS autocheck etc, but unfortunately I don't have towing hook as it's removable, so it's a complete waste on mine.
Click to expand...
thank you ! in the meantime the specific harness I had seen :
Rameder 748972.png
(Erich Jaeger 748972 via Rameder - no affiliation) while looking around appears to be now out-of-stock (2 left a couple days ago?)... so I have no regret to be attempting the fitting of an A3 8L harness, worse come to worse I'll just splice wires the old fashion way. The German site where I had seen photos is a2-freun.de

As for the hitch itself, I suppose monitoring the ads would let you find one eventually (the A4 version of the period may also be fitting, looks very similar - to be confirmed, I'll be trying a 2002 one as a spare - and I've seen two part numbers that looked quite similar on photos 8E0 800 495A and 8E0 800 495 : maybe only a height difference?).
 
Andrew said:
Good Afternoon,

On the flap front from my experience the flap movement (or not) is not particularly noticeable when driving. However the fault codes are pointing at stuck flaps and I suggest you log and post here measurement block 142. Ten seconds will do for a start maybe best with warm engine, start log, start engine, idle for a few seconds and then a heavy rev >3000, let revs return to idle and end log.

Andy
Click to expand...
I've tried today to measure / adapt (?) block 142, yet I'm not sure what I'm doing so this remained somewhat unconclusive: unlike adaptation of block 060 (engine off), which took only a few seconds and ended with ADP ok, 142 seemed to remain a long time "running" (engine off) then I eventually quit, but appeared as ADP.ok when doing some engine running measurements afterward...

graph block 142.jpg

While at it I also tried adaptation of block 074, which kept moving only of small increments (0.100V - 0.360V) a few times over 20 minutes or so (this for the max position, the min position was set at 0.00V), without reaching ADP.ok either.

Then I had to leave so did a few static engine run tests and a small road test, but the car is not very driveable : it seems that the link between pedal position and throttle can get lost in the 1500-2500 range (not always but it makes it unreliable), to the point the engine may stall during parking manoeuvres, and one has to gun it to keep it running. The car runs great when above 3000rpm, though in small streets it's a bit too zippy for confort...

I did a small film of some VCDS parameters when this happens (with block 142), I can try to upload it if of use.

---edit---
fwiw here is some footage of a static test, after ~20" illustrating someting like the electronic throttle (RPM) oscillating by itself (pedal being steady) then displaying block 142 under VCDS... this gets worse on the road (the car stalls easily when it happens during low speed manoeuvers) - I thought about injectors and improper richness so displayed the fuel pressure, then I realize the lambda sensor may also be concerned in these low/medium revs oscillations...
PS: I believe mine is a "full FIS" dashboard (half FIS having a separation in the middle I understand)
 
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The flap adaptation is done with the ignition on, but engine off.
It uses residual vacuum to operate, (raise the flap), which is initially down.
Briefly run the engine, to be sure there is enough stored vacuum to run the adaptation.
Here's the process:

(Credit due to @Sarge who posted this long ago).

Turn the key on but do not start the car.
[Select]
[01 - Engine]
[Measuring Blocks - 08]
Enter Group 060

[Go!]
[Switch to basic settings]

Once you do this you will see the top right display say ADP RUN. The TB adaptation is being done as soon as you switch to basic settings. You will see the values change and hear the TB cycle for the first few seconds then it will stop. Leave it in Basic Settings for about 30 seconds.

[Switch to Meas. Blocks] button and you're all set.

Be sure not to touch the accelerator and make sure the engine is NOT running when you do this!
Mac.
 
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