Towbar installation: would a period harness fit ?

[NicM]

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.

Yes, this I did (block 060 adaptation) and I believe it went just fine (took only a few seconds and ended up with OK status right away under VCDS) - I understand this is the eletronics throttle "butterfly": what I call the "lower manifold flap" (specific of FSI mode) would be under block 142 I understand, and this is where I'm getting a confusing (for me) outcome...

I suspect my problem came up after I tried to spray clean the EGR valve region, possibly by contaminating something or rather by getting unstuck something that was stuck before (or adapted to it's previous range?) - the car was not doing that during the previous 100km or so when I test drove it after fixing various leaks (including the rear plastic "death" tube).

 

[PlasticMac]

thank you ! in the meantime the specific harness I had seen :
View attachment 125661
(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?).

You shouldn't splice the trailer wiring into the car. If you do, then as @bretti_kivi says, you'll have all sorts of problems with the lamp test function. Using a 7 way relay box, isolates and two circuits from one another. The tee into the car only operates each of the 7 very low current relay coild, and the relay's contacts switch the battery supply to the relavant of the 7 lamps: LH & RH indicators, LH & RH tail lights, brake lights, reverse lights, and rear fogs.
Mac.

 

[NicM]

You shouldn't splice the trailer wiring into the car. If you do, then as @bretti_kivi says, you'll have all sorts of problems with the lamp test function. Using a 7 way relay box, isolates and two circuits from one another. The tee into the car only operates each of the 7 very low current relay coild, and the relay's contacts switch the battery supply to the relavant of the 7 lamps: LH & RH indicators, LH & RH tail lights, brake lights, reverse lights, and rear fogs.
Mac.

indeed I was not planning to splice for powering the bulbs, but only to input the relay box in case of lack of a male/female insertion connector set. I'll try to figure that out when I receive the A3 8L kit (though my initial intent is not to cut or splice anything from the original harness if I can, that would be by using connectors only to get the required inputs to the relay box).

 

[nod]

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.

you can get them on ebay reasonably cheap this youtube shows part numbers and cars that use them, cheers

 

[CrispyEdd]

I wired one of these into a skoda superb, https://www.ebay.co.uk/itm/311631953765 , ive had no issues at all. All my light warning stuff from the dash is unaffected. My skoda had half led multifunction and half standard bulbs too at the back! THe A2 is striaghtforward. I popped afuse inline for the power to the relay and jobs done.
To connect the wires i sliced away an inch of insultion, leaving bare wire, then wrapped the relay feed wire tight then soldered it and insulated.

If you have rear sensors and cant override them then theyll go beserk with a trailor on, luckily on my skoda i can mute the,m. OTherwise you need a module that talks to main body control to tell them to switch off when a trialer is connected.

 

[NicM]

Well, just received this (old stock liquidation I believe), so I'll be trying my luck fitting an A3 8L harness (8L0 055 204 D - same kind I've seen ) in August :

At first glance there are in/out piggy back connectors for both rear lights, if they fit that would be perfect - but in any case that will be a factory like harness, a lot cleaner than what I would have hacked with spare wires... and there is the Audi logo on the plug though I need to make a swivel plate to hold it as the one on the towbar has been broken.

 

[Andrew]

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...

View attachment 125663

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)

Good Afternoon,

Apologies for the slow reply to this I have been busy and all this football.

I don't know were to start. First note I never mentioned adaptation and Group 142 as I know it does not work, just hangs as you found out but do follow Mac's suggestions on Basic Settings.

Thank you for the screenshot and video but not what I expected (more later), I am used to looking at numbers. I am not familiar with VC - Scope but on the face of it the green castellation is the ECU requiring the flaps to shut, (fully raised and closing the bottom half of the inlet port) and open (flaps down, fully open) and looks normal. The red graph should mimic the green but it appears the flaps are restricted to about a range of 80% to 100% raised and seem unable to fully lower and open. No doubt carbon deposits bunging everything up and will cause the EML. While on EML club folklore has it the ECU checks the integrity of flap movement at start up and will tolerate the odd failure to reach setpoints but the 'three strikes rule' applies the EML will soon pop up for repeated fails as you have found. You may be able to manually confirm this diagnosis with the Tippex test, details no doubt found in this useful bedtime reading and is almost a potted history of our understanding around flaps.

fault p1031

hi guys, im new to this site and also a relitivley new a2 owner (12months), i love my little car however i have had a few niggles with it and having paid out at main dealers thought i would seek alternative advice, my latest prob is the engine management light being on, its saying fault p1031...

www.a2oc.net

I would still be interested in the log I requested but I will add some more detail as you are new to VCDS.

With a warm engine before starting the engine with ignition key in first position start VCDS and navigate to Measuring blocks and select Group 001 and 142. Click the 'log' button at the bottom right of the screen. Pause a second and start the engine, allow to idle for a second, a few revs and hold at 4000 rpm for 3 seconds, let revs reduce to idle. I am writing this from memory and might not be spot on but a 'Stop log' button should have appeared when you previously click 'log'. Click 'Stop log'. Stop the engine and close down VCDS. The log file is the complete collection of measuring block values that flashed before your eyes a minute ago when using VCDS and is saved in the Ross-Tech folder on C: drive in a .CSV file (Comma Separated Value) suitable for spreadsheet software. Using Excel or similar load this file, It can be found in C:>Ross-Tech>VCDS>Logs if you wish to view the data. However all you need do is attach this file to a post in this thread.

Other points.

Do not be apprehensive about stripping the lower manifold for cleaning if the need arises, allow a day, the injectors will come out with a tug and wiggle (even a cheap special tool is available) but you are supposed to replace the seals. The only trouble is it is like opening a can of worms, once injectors out maybe wise to send off for professional cleaning and checking, more cost about £120 in the UK. With manifold off good opportunity to replace death pipe, maybe thermostat housing and thermostat too, more work, more cost see what I mean.

Finally, sorry to ramble, I reiterate my earlier point that I cannot see the flaps are the cause of the kangaroo behaviour, sort that and live with EML for a time, I would come back to it and leave on the back burner for now, stuck flaps generally do not interfere too much with running.

Andy

 

[PlasticMac]

Good Afternoon,

Apologies for the slow reply to this I have been busy and all this football.

I don't know were to start. First note I never mentioned adaptation and Group 142 as I know it does not work, just hangs as you found out but do follow Mac's suggestions on Basic Settings.

Thank you for the screenshot and video but not what I expected (more later), I am used to looking at numbers. I am not familiar with VC - Scope but on the face of it the green castellation is the ECU requiring the flaps to shut, (fully raised and closing the bottom half of the inlet port) and open (flaps down, fully open) and looks normal. The red graph should mimic the green but it appears the flaps are restricted to about a range of 80% to 100% raised and seem unable to fully lower and open. No doubt carbon deposits bunging everything up and will cause the EML. While on EML club folklore has it the ECU checks the integrity of flap movement at start up and will tolerate the odd failure to reach setpoints but the 'three strikes rule' applies the EML will soon pop up for repeated fails as you have found. You may be able to manually confirm this diagnosis with the Tippex test, details no doubt found in this useful bedtime reading and is almost a potted history of our understanding around flaps.

fault p1031

hi guys, im new to this site and also a relitivley new a2 owner (12months), i love my little car however i have had a few niggles with it and having paid out at main dealers thought i would seek alternative advice, my latest prob is the engine management light being on, its saying fault p1031...

www.a2oc.net

I would still be interested in the log I requested but I will add some more detail as you are new to VCDS.

With a warm engine before starting the engine with ignition key in first position start VCDS and navigate to Measuring blocks and select Group 001 and 142. Click the 'log' button at the bottom right of the screen. Pause a second and start the engine, allow to idle for a second, a few revs and hold at 4000 rpm for 3 seconds, let revs reduce to idle. I am writing this from memory and might not be spot on but a 'Stop log' button should have appeared when you previously click 'log'. Click 'Stop log'. Stop the engine and close down VCDS. The log file is the complete collection of measuring block values that flashed before your eyes a minute ago when using VCDS and is saved in the Ross-Tech folder on C: drive in a .CSV file (Comma Separated Value) suitable for spreadsheet software. Using Excel or similar load this file, It can be found in C:>Ross-Tech>VCDS>Logs if you wish to view the data. However all you need do is attach this file to a post in this thread.

Other points.

Do not be apprehensive about stripping the lower manifold for cleaning if the need arises, allow a day, the injectors will come out with a tug and wiggle (even a cheap special tool is available) but you are supposed to replace the seals. The only trouble is it is like opening a can of worms, once injectors out maybe wise to send off for professional cleaning and checking, more cost about £120 in the UK. With manifold off good opportunity to replace death pipe, maybe thermostat housing and thermostat too, more work, more cost see what I mean.

Finally, sorry to ramble, I reiterate my earlier point that I cannot see the flaps are the cause of the kangaroo behaviour, sort that and live with EML for a time, I would come back to it and leave on the back burner for now, stuck flaps generally do not interfere too much with running.

Andy

A "Suck it and See" test is also useful.
The flaps are vacuum operated, so if you disconnect the vacuum tube from the actuator, then fit a length of tube to the actuator, and suck on it, the flaps will move, exactly as they would under engine/vacuum power. If you either log, as per @Andrew while sucking, or employ a helper to suck for you, (a sucker), you'll be able to see if the arc of movement is the same, and you can see the linkage mechanism, between the actuator and the flap spindle bell crank, too, which can, and does fail, it's only plastic.
Mac.

Video of Suck it and See here:

This video is an @ICowie production.

 

[NicM]

Good Afternoon,

Apologies for the slow reply to this I have been busy and all this football.

I don't know were to start. First note I never mentioned adaptation and Group 142 as I know it does not work, just hangs as you found out but do follow Mac's suggestions on Basic Settings.

Thank you for the screenshot and video but not what I expected (more later), I am used to looking at numbers. I am not familiar with VC - Scope but on the face of it the green castellation is the ECU requiring the flaps to shut, (fully raised and closing the bottom half of the inlet port) and open (flaps down, fully open) and looks normal. The red graph should mimic the green but it appears the flaps are restricted to about a range of 80% to 100% raised and seem unable to fully lower and open. No doubt carbon deposits bunging everything up and will cause the EML. While on EML club folklore has it the ECU checks the integrity of flap movement at start up and will tolerate the odd failure to reach setpoints but the 'three strikes rule' applies the EML will soon pop up for repeated fails as you have found. You may be able to manually confirm this diagnosis with the Tippex test, details no doubt found in this useful bedtime reading and is almost a potted history of our understanding around flaps.

fault p1031

hi guys, im new to this site and also a relitivley new a2 owner (12months), i love my little car however i have had a few niggles with it and having paid out at main dealers thought i would seek alternative advice, my latest prob is the engine management light being on, its saying fault p1031...

www.a2oc.net

I would still be interested in the log I requested but I will add some more detail as you are new to VCDS.

With a warm engine before starting the engine with ignition key in first position start VCDS and navigate to Measuring blocks and select Group 001 and 142. Click the 'log' button at the bottom right of the screen. Pause a second and start the engine, allow to idle for a second, a few revs and hold at 4000 rpm for 3 seconds, let revs reduce to idle. I am writing this from memory and might not be spot on but a 'Stop log' button should have appeared when you previously click 'log'. Click 'Stop log'. Stop the engine and close down VCDS. The log file is the complete collection of measuring block values that flashed before your eyes a minute ago when using VCDS and is saved in the Ross-Tech folder on C: drive in a .CSV file (Comma Separated Value) suitable for spreadsheet software. Using Excel or similar load this file, It can be found in C:>Ross-Tech>VCDS>Logs if you wish to view the data. However all you need do is attach this file to a post in this thread.

Other points.

Do not be apprehensive about stripping the lower manifold for cleaning if the need arises, allow a day, the injectors will come out with a tug and wiggle (even a cheap special tool is available) but you are supposed to replace the seals. The only trouble is it is like opening a can of worms, once injectors out maybe wise to send off for professional cleaning and checking, more cost about £120 in the UK. With manifold off good opportunity to replace death pipe, maybe thermostat housing and thermostat too, more work, more cost see what I mean.

Finally, sorry to ramble, I reiterate my earlier point that I cannot see the flaps are the cause of the kangaroo behaviour, sort that and live with EML for a time, I would come back to it and leave on the back burner for now, stuck flaps generally do not interfere too much with running.

Andy

thank you very much for your detailed reply: unfortunately I'll only be able to try out the checks and measurements by the end of the month, as I'll be away from the storage for a couple weeks...

 

[NicM]

A "Suck it and See" test is also useful.
The flaps are vacuum operated, so if you disconnect the vacuum tube from the actuator, then fit a length of tube to the actuator, and suck on it, the flaps will move, exactly as they would under engine/vacuum power. If you either log, as per @Andrew while sucking, or employ a helper to suck for you, (a sucker), you'll be able to see if the arc of movement is the same, and you can see the linkage mechanism, between the actuator and the flap spindle bell crank, too, which can, and does fail, it's only plastic.
Mac.

Video of Suck it and See here:

This video is an @ICowie production.

I have a vacuum setup for purging brakes: I'll try that to confirm the condition of the FSI flaps with it... though my eventual goal would be to rid of this FSI mode (by getting the ECU reprogrammed in Germany if nothing else properly does it, which also would let the coolant run cooler I understand and hopefully prolong the lifetime of all these plastic hoses). Will try to post back on that FSI flap issue in August...

 

[NicM]

I swung by the storage today and did a quick test of the A3 harness: it appears to fit ! the connectors were directly piggy backed to the left and right rear light and the lights of the car still work...



I now need to look into more in detail the rest of the wiring (including the trailer module power to be pulled after a fuse - and the red wire that would be connected to the APS Acoustic Parking System, in position 5/16 on the A3 module plug), but I'm now confident most of the work will be the mechanical installation (esp. I'm missing the front spacers/holders for the tubes, that I will have to make).

The keys ordered in the UK from the engraved lock number work well, and the hook can be removed from the tow bar now (required for a clean installation with minimal hole in the bumper).


-----A "Suck it and See" test is also useful.
I also did a quick vacuum test of the FSI actuator using a manual pump (Mytivac - usually for brake bleeding, no affiliation on my part) : it seems the actuator is not broken, though I suspect it does not move the whole intended range (I would think about a 1/4 turn would be required, yet on the video quoted above it may be less, plus it may move a little bit more when the engine is running thanks to the vibrations...). The following video shows a pumping cycle and release

(engine still behaves the same, ok cold, then revs oscillate say +/- 500rpm under a steady pedal when going above idle but below ~2500 rpm, typically).

In any case, a friend should bring me a spare ECU from the UK that I plan to get reprogrammed so that the FSI mode is cancelled - at least that part would not cause throttling issues then.

 

[NicM]

A few afternoons later, the tow bar and A3 wiring kit have been installed:

The missing supporting pieces were made of 6063 aluminium tube (15mmID 25mmOD), cut with a 25mm holesaw and filed to fit the ~27mm round bars. An M8 screw pulls the bar against the 50x75mm holding plate (I had ordered some 5mm flat for that but when drilling the frame it turned out to be 3mm so I used some 3mm I had lying around without waiting), which is sealed and riveted to the frame. I originally meant to weld the tubes on the flats, but eventualy only epoxy glued them to save time (this is to reduce the risk of losing the tubes inside the frame if someone undoes the tow bar without removing these two supports first). The small supporting tubes are about 24mm tall from flush of the frame to the lowest point of the 27mm tubes (they were maked in place and filed to fit).




The center of the M8 supporting screw in the 27mm support round bars is 155mm front of the vertical plates holding the tow bar (3 M8 screws each).

A couple holes were made in the rear bumper to let the hook and swiveling plate go through (marked on masking tape and cut with an oscillating saw between stress relief holes, quite easy). I actually switched to the A4 spare hook I had sourced locally, in better condition than the one that came with the tow bar and must have stayed outside quite some time (the locking mechanism springs in and out quite nicely, and it came with the two original keys). The tow hook fits nicely in the trunk, in a hole made for it with the key on in the dark foam.


The A3 harness turned out to be a bit short for the outside part, probably due to different location of the through hole (I could not route the RHD like OEM and had to go along the shortest route behind the plastic plate). The "red wire", which I understand stops the APS/PDC parking sound when a trailer is plugged in (there is a little switch embedded in the Audi trailer plug, to that end I suppose), had to be lenghtened (the parking module is on the RHS of A3 and LHS on A2), I probably could have undone it from the harness but eventually did not want to mess with the Audi wrapping.

ps: I was surprised by the weight of the original bumper reinforcing bar, as if the blocks and crumple bow are alloy there is a hugh solid steel piece that goes across, possibly 30x30mm, so that it may weight event more than the towing package which is all steel... would that be for weight balance?

 

[MikeMiles]

A really impressive use of the A3 towbar electrics I think

Did you choose the A3 kit specifically over say an A4 of the same time period? Or was this kit simply available when you were looking?

I am in the same position of having fitted a towbar but with no electrics yet, so I wonder if one is better than the other?

Regarding the weight of the bumper beam versus the tow bar: I don't remember the bumper being all that heavy, but I do remember the towbar being very heavy during fitting! The bumper only needs to withstand impacts, but the towbar needs to do that plus withstand the bending and torsion loads from the trailer hitch...

 

[NicM]

A really impressive use of the A3 towbar electrics I think

Did you choose the A3 kit specifically over say an A4 of the same time period? Or was this kit simply available when you were looking?

I am in the same position of having fitted a towbar but with no electrics yet, so I wonder if one is better than the other?

Regarding the weight of the bumper beam versus the tow bar: I don't remember the bumper being all that heavy, but I do remember the towbar being very heavy during fitting! The bumper only needs to withstand impacts, but the towbar needs to do that plus withstand the bending and torsion loads from the trailer hitch...

I had seen on a German website an OEM harness number (though not easily or affordably available here), then thought of looking for Audi harnesses of the same period if at all to get the connectors and make my own more cleanly than just splicing the original harness - and by chance I found locally a NOS period A3 harness cheap enough for me to give it a try... I since have found the same ones for a bit more on an auction site (in Poland iirc). So I have not planned or studied for the best fit, this is just one random attempt (not a perfect fit but good enough for me).