Volkswagen Passat Forum banner

21 - 40 of 63 Posts

·
Registered
Joined
·
138 Posts
Discussion Starter #21
When I replaced sensor both plugs and wires in fender looked good. Or do you mean a connection further up the line?
 

·
Registered
Joined
·
138 Posts
Discussion Starter #24
Well that didn’t work, same LF code. May be ABS control module.
 

·
Registered
Joined
·
138 Posts
Discussion Starter #25
Would anyone know where I can find wiring diagram that would show the path from my LF ABS sensor to computer? Think that would be another step I could take to try to figure out why I keep pulling a code. Seems to me possibly electronic rather than wiring only because I can drive it for half hour with no light then light comes on after letting idle in driveway for 15 min. Thanks
 

·
Registered
Joined
·
348 Posts
Would anyone know where I can find wiring diagram that would show the path from my LF ABS sensor to computer?
From the Brake system section, front axle, is the same for all 2002+:

abs_front_axle_components_2002_or_later.jpg abs_front_axle_sensor_2002_or_later.jpg

From the wiring section, ABS, is the same for all 2002+:

abs_wiring_75-1_for_2002_or_later.jpg abs_wiring_75-2_for_2002_or_later.jpg abs_wiring_75-3_for_2002_or_later.jpg abs_wiring_75-4_for_2002_or_later.jpg abs_wiring_75-5_for_2002_or_later.jpg abs_wiring_75-6_for_2002_or_later.jpg

If you are having trouble with the diagrams the arrows just mean from one page to the next so like 75-1 a right arrow means go to 75-2. If you have any other questions hopefully someone else knows because I'm not too familiar with understanding the diagrams. Good luck!
 

·
Registered
Joined
·
138 Posts
Discussion Starter #28
Haven’t looked in plug of ABS module yet other than the other day to check for corrosion but does anyone know if pins are numbered since its a 42 pin connector, or do I need a diagram to find my pins for LF wheel speed sensor. Thanks to the last post I was able to find out pin numbers and wire colors. Also what is code ATQ ? because that can change which pin Im looking for. Thank you
 

·
Registered
Joined
·
348 Posts
ATQ is the V6 engine for 2000-2005 so that's your engine. Connectors may have a number on the edge like 1 18 or whatever so you get some idea of where everything is even if each pin isn't individually numbered.That particular connector I don't know though. It looks like pin 1 is brown ground. Consider vcds lite and a generic cable which is much cheaper, what you can do is limited but I'm pretty sure you can read the abs module. I have full vcds and it's been very helpful ,at some point you might need it but it is expensive even if you buy it used.
 

·
Registered
Joined
·
138 Posts
Discussion Starter #30
Going to check continuity at least from connector in fender well to ABS mod. The sensor I installed was a very cheap (inexpensive) one so just for the hell of it I have a better one coming tomorrow just to eliminate it. I couldn’t find out what the actual resistance should be when looking across with ohm meter. One suggestion was to swap sides and see if trouble follows but would rather leave right side alone for now. Did look in to VCDS, it would really give me more troubleshooting options like watching sensor live. If I worked on VW, Audi vehicles for a living it would be a no brainer. I really appreciate all your help, joining this group is best thing I have have done to figure these German rigs out. Wish I could go back to distributors, coils, points and no electronics.
 

·
Registered
Joined
·
138 Posts
Discussion Starter #31
Have been trying to figure out what generic cord to get for VCDS lite. A little confusing. Would you recommend one?
 

·
Registered
Joined
·
348 Posts
I'd follow Ross Tech's guidelines and get one that explicitly says it has an FTDI chip FT232. I'd also order from a seller in the United States so it would arrive within a week instead of the month it would take from China. Here's one with ft232 for $12 and here's one for half that but it doesn't say what chip it uses. If you have Amazon prime here's one that in most of the reviews says it works with VCDS lite.

In any case they may come with a tiny cd with pirated software. I'd discard it and download VCDS lite directly from ross tech. If I remember right they have a USB option in the software (I don't know if the lite version has this) so that it's able to find the cable immediately. FTDI has their drivers at Virtual COM Port Drivers but I don't know if you'd really need them.
 

·
Registered
Joined
·
138 Posts
Discussion Starter #33
Thanks. Will get that cord from Amazon then pay the $99 from Ross Tech and give it a try. Will post after I give it a try.
 

·
Registered
Joined
·
348 Posts
You may be able to access the ABS without paying the $99 to register it. It looks like the shareware version doesn't stop you from opening any specific module it just has restrictions on what you can do within the modules depending on whether you paid. The fault codes section in the ABS module is probably what you would look at first. If you haven't paid the $99 it will show you the codes without the text, so you'd have to google each code then find the link to the diagnosis for that code on ross tech's website. It will show you common causes for the code and troubleshooting info for some. It's a little bit of a nuisance but it's free. (edit: Actually now that I think about it I end up googling all the codes anyway so it's not really a nuisance.)
 

·
Registered
Joined
·
138 Posts
Discussion Starter #35
I currently have a VW-Audi scan tool ( cheap one) that allows me to access everything including ABS. I used it on my Jetta and lucked out because it told me which wheel had issue, replaced sensor and all was good. The Passat not so lucky, it says LF but new sensor didn’t correct. Was hoping the VCDS lite would let me look at each signal live while moving.
 

·
Registered
Joined
·
138 Posts
Discussion Starter #36
Update. Probably don’t matter but finding black on pin 12 and green on 28 from LF wheel speed sensor which is backwards according to wire diagram I have. At least no open. Doubt very much someone reversed, would be hard to do.
 

·
Registered
Joined
·
138 Posts
Discussion Starter #38
Took a look at that link, thanks. With mine the two wires end up in the two locations the diagram shows just backwards so they must have always been like that, weird. So I’m in same situation with a light and LF code. Another thing I tried was to short wires in plug in wheel well, left first and light would be out but LF code shows, eventually light would come on. So put that back together and did same on right side, that made light come on and stay on and only code was LF so I gave up for the night. Not going to give up since car was given to me with new tires, new brakes, new exhaust.
 

·
Registered
Joined
·
348 Posts
ABS sensors are sensitive to gap. The gap from the sensor cylinder to the teeth is precise so as the teeth pass over it a magnetic field is generated (or something like that). I don't think shorting is going to work, my guess is a little bit of current is sent based on how fast the wheel is turning. Check this out:


Another thing is even if you do have a proper response it's possible the computer could be comparing it to the other sensors and maybe there's too much difference. However since you said it happens when you start and stop it I think that's probably unlikely. The test that guy did in the video where he rolls the car to see the sensor output would probably be useful in your case.
 

·
Registered
Joined
·
138 Posts
Discussion Starter #40
Excellent video, I have trouble finding good ones like that. My cord from Amazon will be here tomorrow, then I will probably download VCDS lite and hopefully be able to watch each sensor, till then I will look in to why parking brake is froze hard. Person that had this car was not in to maintenance. Thank you.
 
21 - 40 of 63 Posts
Top