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Old May 22nd, 2001, 09:41   #1
Drivbiwire
Zehntes Jahr der Veteran
 
Join Date: Oct 1998
Location: Boise, Idaho
Fuel Economy: Who cares, it's a diesel!
Default Pedal repair, Procedure and Pictures

I got a phone call yesterday from the chip master himself GarrettP "my car is broke". He gave me directions on how to get to him as it turned out he was only about 15 miles from my house (lucky him [img]images/icons/grin.gif[/img]).

Anyway I asked him what happened and all he knew was that using his Vag-Com (Ross-Tech cable) to read the fault codes he was reading a code 18048. He had called the dealer and they had no clue what it was. The symtoms were when you start the car and it idles normally then when you press the pedal nothing I mean absolutely nothing happens, except after a few seconds the engine revs up to around 1100 rpm and stays there. I told him its the G79 sensor (Gas pedal) and that the ECU deteceted a fault and is overriding the pedal to prevent a runaway vehicle. The engine will flash the famous engine light and go into high idle mode. What this does is allow you to get home (limp mode if you will).

The car can be driven without any problems the catch is you won't be going very fast. The engine when the clutch is released will spin on up to around 1300 rpm to allow you to shift into a higher gear and then settle down to 1100 rpm and stay there. Its pretty neat to see but in 5th gear this only gets you upto a blurring 35mph [img]images/icons/wink.gif[/img]. Since 35mph was not gonna cut it on I-94 at rush hour with road construction in the Chicago area we pulled over and I hooked up my tow rope and pulled him along at 70 so that we did not get run over by the Semi's.

We got back to my house and he helped me unload the trailer from the GTG and Hondos (Thanks again G, my back thanks you also). He started the car up and pulled it into the garage and we looked it over to make sure that there was nothing else that could be causing this. Because the Engine had control of RPMs this assured us that nothing in the Injection pump was broken, we had to make sure that because he was running a Beetle ECU in the car and a tuning box that everything was connected corrrectly... [img]images/icons/rolleyes.gif[/img]

As it turned out all indications lead back to the pedal sensor. The part number on a 2000 Jedi TDI (Jetta, Golf and Beetle for the rest of us) is IJI 721 503H

Picture of the part number: http://tdipics.mmcorp.net/members/drivbiwire/GarrettP's%20Throttle/2001_0521_172253AA .JPG

Garrett called up his parts guy and orderd a new one. The price was $107.00. Of course they did not have it in stock and it would have to get overnited the following day because they could not ship this late in the day so at best we wer looking at 3 days of downtime. SO, we took it apart to see if we can fix it!

The code 18048 is a 1+2 out of range/scale code. What that means is this. The TDI uses two position sensors both are looked at by the ECU and compared to make sure the ECU does what the driver is requesting. If one or both disagree you get this high idle conditon and the ECU takes away throttle control to prevent the car from running away from you.

The sensor is perhaps the simplest gadget I have yet seen in a TDI and uses four carbon tracks and four wire brushes for contacts. Each sensor uses two tracks in series to reduce the length of the sensor card yet retain the total strip length for precise throttle control.

Picture of the Throttle card: http://tdipics.mmcorp.net/members/drivbiwire/GarrettP's%20Throttle/2001_0521_171848AA .JPG

Picture of the brush contacts: http://tdipics.mmcorp.net/members/drivbiwire/GarrettP's%20Throttle/2001_0521_172411AA .JPG

As we found out later the sensor over time can move off of the carbon tracks because of the brushes flattening or due to the carbon tracks wearing and cause this error code. What happens is the ECU detects a set of brushes making contact and the other set is not, so the ECU shuts down the pedal.

How you fix it is easier yet. there are 5 screws:
http://tdipics.mmcorp.net/members/drivbiwire/GarrettP's%20Throttle/2001_0521_172750AA .JPG

Remove the black screw (this is a lock down screw) loosen the other four and you can now rotate the sensor plate. We could not measure how much but the more you move it the more sensitive the pedal gets to movement (Garrett is really sensitive now [img]images/icons/grin.gif[/img]).

Anyway we plugged the pedal back into the car and moved the sensor until the pedal had the response Garrett was acustomed too. Then tightened the chrome screws and we reinstalled the black screw.

Picture of the screws and the elongated holes http://tdipics.mmcorp.net/members/drivbiwire/GarrettP's%20Throttle/2001_0521_180502AA .JPG


The mounting of the peadal is very simple and only requires a 10mm deep socket and an extension. The plug is a typical plug like the one you will find in the tail lights:

Picture of pedal mounting point and wire:
http://tdipics.mmcorp.net/members/drivbiwire/GarrettP's%20Throttle/2001_0521_172510AA .JPG

There are four studs and only three of them are used, just remount the pedal on the ones you took the pedal off of. They will be marked with white paint so you won't be able to mix them up. If you want run an extension cord and let your back seat passengers work the throttle if you want [img]images/icons/wink.gif[/img].

Picture of the whole pedal assembly: http://tdipics.mmcorp.net/members/drivbiwire/GarrettP's%20Throttle/2001_0521_172818AA .JPG

Picture of the inside of the sensor plate: http://tdipics.mmcorp.net/members/drivbiwire/GarrettP's%20Throttle/2001_0521_171926AA .JPG

Picture of 6 spring loaded contacts that hold the conact plate in position:
http://tdipics.mmcorp.net/members/drivbiwire/GarrettP's%20Throttle/2001_0521_172149AA .JPG

Picture of the back of the pedal assembly: http://tdipics.mmcorp.net/members/drivbiwire/GarrettP's%20Throttle/2001_0521_180820AA .JPG

Keep in mind that on the A3's the pedal sensor may be different in design. I hope this helps out someday. Garrett has 67,000 miles on his car so I am sure as the pedal sensors wear this will become more of an issue. The fix is simple and on a scale of 1-10 on complexity it easily gets a 1.

DB

[ May 22, 2001: Message edited by: Drivbiwire ]
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Old May 22nd, 2001, 10:02   #2
SkyPup
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Default Re: Pedal repair, Procedure and Pictures

Garrett must have brought this on himself with all that stomping on the GO-Pedal!! [img]images/icons/grin.gif[/img] Perhaps driving barefooted would have prolonged the life of this sensor mechanism [img]images/icons/rolleyes.gif[/img]

Nice write up and presentation of what could be a perplexing problem.
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Old May 22nd, 2001, 10:03   #3
VelvetFoot
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Location: Sand Lake, NY
Default Re: Pedal repair, Procedure and Pictures

Very nice writeup.

Did you clean anything or just move things? It sounds like you just moved things.
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Old May 22nd, 2001, 10:19   #4
Drivbiwire
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Join Date: Oct 1998
Location: Boise, Idaho
Fuel Economy: Who cares, it's a diesel!
Default Re: Pedal repair, Procedure and Pictures

We did clean off the caron block with some special electronic contact brush cleaner/lubricant that Garrett had.

Everything looked just about brand new and there was no visible wear on anything. The two interior contacts looked a bit bent other than that nothing at all.

DB
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Old May 22nd, 2001, 11:10   #5
banzai
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Join Date: Oct 2000
Location: East Overshoe, ME
TDI(s): NB TDI
Fuel Economy: 47 all the time
Default Re: Pedal repair, Procedure and Pictures

Do you think this is a maintainance item- clean it look at it before it strands you?
Does look like something that would wear out-/get dirty
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Old May 22nd, 2001, 12:08   #6
GeWilli
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Location: lost to new england
Fuel Economy: you keep track?
Default Re: Pedal repair, Procedure and Pictures

was this after the Road and Track visit?

geesh - I'll check the pics later - sounds like it might call for a manifold cleaning party kinda thing [img]images/icons/wink.gif[/img]

another excuse for a GTG . . . .
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Old May 22nd, 2001, 14:21   #7
Drivbiwire
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Join Date: Oct 1998
Location: Boise, Idaho
Fuel Economy: Who cares, it's a diesel!
Default Re: Pedal repair, Procedure and Pictures

I think this is one of those things where if it's not broke, don't fix it.

The thing is it won't leave you stranded and you will be able to motor your way home, abeit slowly.

I spoke with Garrett and I guess it acted up again, he adjusted it and its fine. The only thing going on now is the sensitivity sometimes its hard to maintain a certain speed using the pedal (entirely due to the sensitvity this may be able to be adjusted out by adjusting the contact plate).

Anyway he is gonna drop in and post his observations later.

DB
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Old May 23rd, 2001, 09:51   #8
kato258
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Default Re: Pedal repair, Procedure and Pictures

GREAT post!! another $107 out of vwoa coffers! of course, i supposed they could have cleaned it instead of replacing it. right!

thanks to garrett for being the guinea pig.

does fred have a location to store fixes like this? like a read-only reference forum (i guess it wouldn't be a forum anymore).
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Old May 23rd, 2001, 10:13   #9
NYTDI
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Join Date: Mar 2001
Location: Mid - Hudson
Default Re: Pedal repair, Procedure and Pictures

and meanwhile I was calling Garrett complaining about my 4000rpm cutout [img]images/icons/rolleyes.gif[/img]

Garrett, you must have been thinking something like "how would you like a 1300rpm limit" [img]images/icons/rolleyes.gif[/img]

Hope it stays fixed and not too "sensitive"
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Old May 23rd, 2001, 10:26   #10
michTDI
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Join Date: Sep 2000
Location: Charlotte, MI, USA
Default Re: Pedal repair, Procedure and Pictures

So-GarrettP is now a "sensitive New-age Guy" (snag)???? Only 15 miles from DBW's house??? Is GarrettP lucky or what???? Hey GarrettP-can you select some lottery numbers for me????
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Old May 23rd, 2001, 11:13   #11
tom
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Join Date: Sep 1999
Location: Tucson, Arizona, USA
Default Re: Pedal repair, Procedure and Pictures

Nice descriptive post, but it leads me to the thought of overall reliablility due to the number of gadgets and gizmos on these tdi's. How many of us have ever had to repair the fuel/gas pedal on an automobile before?
Especially to the tune of $107.00 bucks. I can just hear Ric screaming now!!! [img]images/icons/shocked.gif[/img] [img]images/icons/shocked.gif[/img]
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Old May 23rd, 2001, 11:29   #12
Drivbiwire
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Join Date: Oct 1998
Location: Boise, Idaho
Fuel Economy: Who cares, it's a diesel!
Default Re: Pedal repair, Procedure and Pictures

I wore the cable outon my 85 Golf 3 times, along with 2 clutch cables, countless sets of brake pads.... I chalk this up to a wearable item.

The pedal sensor should be good for at least 300K+. It is just odd that his did this. I can say that there really was no visible wear at allon any of the carbon tracks.

Yes it's true that there are a lot of gizmos on these cars but when you look at the overall reliability and the convenience they provide its pretty hard to beat.

So far this is the first time I have heard of ANY Drive-By-Wire type pedal doing this.

If I had a choice between this type of linkage and my old Golfs cable I would take this new sytem any day of the week.

DB
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Old May 23rd, 2001, 11:39   #13
Chiefbob
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Join Date: Feb 2001
Location: Lake Bluff, IL, USA
Fuel Economy: 54/48/42
Default Re: Pedal repair, Procedure and Pictures

DB another great post. I never stop being impressed with your knowledge and willingness to share that knowledge...But not only to fix Garret's car but also make him sensitive is a big deal. All Garret's friends thank you.
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Old May 23rd, 2001, 16:18   #14
garrettp
Former Chip-Monk
 
Join Date: May 2000
Location: Oconto, WI
TDI(s): 2000 JEDI
Default Re: Pedal repair, Procedure and Pictures

hey, i have always been a sensitive guy [img]images/icons/wink.gif[/img]

i cannot thank Pete enough for all that he has done. i am sure if i started to add up all that he has saved me (tow to dealer, dealer replacing ECU cuz they are stoopid.. and all the other goodies) this would not have been cheap. THANK GOD PETE WAS HOME

i am glad to be the guniune pig for all. and you guys think i am putting on all these miles cuz i like to drive [img]images/icons/grin.gif[/img]. nope, it is to test the reliability of parts on cars, i am happy to do it and it just so happens that it coincides with alot of GTG's and chipping [img]images/icons/wink.gif[/img]

a note on mainentance of the parts, the brushes are very fnie and sensitive i think a few may have gotten bent whilst cleaning and my car seems to surge a bit. i would stay away from cleaning them all together. except maybe running some emery cloth softly under them to clean the contact area. again though, they are very sensitive.

i did call the dealer that i drive cars around for and i can get the same part for $60 so i am going to order one and mount it to my dash or in the back seat as Pete had suggested (for all the back seat drivers [img]images/icons/tongue.gif[/img]).

and while i am at it, please check out the problem that NYTDI is having with his newly chipped '99 Auto TDI. i need for him to have a fully functional car to red line [img]images/icons/frown.gif[/img]. click * HERE * for the thread

cudo's to Pete and the like as all you TDI'ers are awesome people.

Mr. g-man sensitive

[ May 23, 2001: Message edited by: garrettp ]
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Old May 23rd, 2001, 16:43   #15
GoFaster
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Join Date: Jun 1999
Location: Brampton, Ontario, Canada
Default Re: Pedal repair, Procedure and Pictures

THIS is a new one! It's going in the archives right now, for future reference!

Brian P.
'96 Passat TDI mit UPsolute
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