Drivbiwire
Zehntes Jahr der Veteran
- Joined
- Oct 13, 1998
- Location
- Boise, Idaho
- TDI
- 2013 Passat TDI, Newmar Ventana 8.3L ISC 3945, 2016 E250 BT, 2000 Jetta TDI
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
).
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
. 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...
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
).
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
.
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 ]
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
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...
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
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
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 ]