Speed Sensor Question

motoracer47

Active member
Joined
Jan 19, 2014
Location
New Braunfels, TX
TDI
2013 Passat TDI SEL 2011 Touareg TDI LUX
Hi,

I realize this question if going to be somewhat vague, sorry about that.
Looking at a 2001 Jetta (ALH) that the seller says needs a speed sensor. They say the car runs fine, and its not in any sort of limp mode. From researching this on the web, I am getting conflicting results. Here is what I have read so far.

That the VSS is on the diff portion of the casing, and cannot be removed without transmission disassembly.

That the VSS is on the diff portion of the casing, and CAN be removed from the transmission. (without disassembly)

That there are other speed sensor(s) inside the transmission that require that the transmission be disassembled.

That often when a code is thrown for a speed sensor, that it is actually the TCM, and a TCM replacement fixes the problem.


I have not looked at the car yet, so I do not have any codes. I don't own a VAG-COM yet, but I do have a program called CARPORT that uses VAG K+Can Commander 1.4 interface, that can read VAG specific codes. (its similar to VCDS, but maybe not as advanced)


I guess my question is, if there are speed sensors inside the transmission, what codes will I see that signifies this?
Next question..Can the VSS on the diff be changed without disassembly of the transmission?

If its easier to wait until I pull the codes, no worries, I can do that, just thought Id ask incase someone knew for sure.

thanks for any help
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
On both the manual and automatic gearbox bolted to the ALH, the VSS is the same, and is easily removed from the top of the diff.

The VSS drive however, is bolted to the top of the case, and requires removal of a bolt to the clamp to slide out, and that is just the driven gear. The gear that drives that is pressed on to the diff carrier assembly.

So what exactly are you talking about here?

There are also speed sensors at each wheel, the crankshaft, and the automatic trans also has its own speed sensor.
 

motoracer47

Active member
Joined
Jan 19, 2014
Location
New Braunfels, TX
TDI
2013 Passat TDI SEL 2011 Touareg TDI LUX
Amazingly fast response!! thanks :)

So what exactly are you talking about here?
Well, not exactly sure. I have not actually looked at the car yet, only going by what the seller mentioned in the ad. It is probably best for me to wait until I see it, pull some codes, and drive it to see what the symptoms are. I know the seller has been driving the car this way for some time, and that whatever the problem is, apparently does not affect the drivability of the car or cause limp mode. Logic would tell me if it was a simple fix, it would have already been done, but maybe not.

You answered my question perfectly about the VSS.
Doing a little more research I found a thread that shows pics of the removal of the top portion of the VSS, and the driven gear (once bolt and clip removed) from the top of the trans casing. The same thread mentioned that the drive gear that is pressed on the diff can be removed without cracking the case. It requires removing the passenger side axle and flange.
All that sound correct?
Heres a linky to the thread http://forums.tdiclub.com/showthread.php?t=336952

My main concern is that there was some speed sensor not accessible from the outside of the transmission. But from further searching, it appears G22, G38, and G68 are all accessible externally.

If it ends up being the engine speed sensor, or a wheel speed sensor, I don't think I will have any issues, as they look (assuming?) easy to replace.

(when I searched, I only searched MK4 sub forum, expanding that to the entire site returned many more results...my bad)
 

djd58

Veteran Member
Joined
Jan 20, 2007
Location
Horseshoe bend, Arkansas
TDI
2003 Jetta TDI, 2001 Golf TDI,2011 Golf TDI, 2012 Passat TDI 2014 Q5 tdi
pull the speed sensor and check the gear, if the gear on the diff is bad the gear on the sensor will be chewed up, if it is chewed up the trans will have to come out to change it
 

motoracer47

Active member
Joined
Jan 19, 2014
Location
New Braunfels, TX
TDI
2013 Passat TDI SEL 2011 Touareg TDI LUX
djd58..
So this (below) is not true? (Btw, this is an auto trans car)

As far as the plastic gear on the diff carrier, if it is a auto trans,it's possible to change without removing trans. I did one 2 wks ago on a Jetta that kept having VSS fault & trans going in limp mode. On the auto trans, remove pass side axle & flange. Measure depth, mark location of lock ring. Remove retainer,unscrew lock ring & you'll see a metal retaining ring-plastic gear goes behind it,pop out retainer & your ready for new parts. Always repace metal retainer & plastic gear


Btw, I don't own this car, its a car im looking at buying, so pulling the VSS probably isn't a possibility :)
Just trying to get a feel for the various things that it could be so when I test drive it and pull codes, I have an idea of what Im looking at.
Regardless, Im going to go check it out this weekend, will report back with what I find. (symptoms and codes)
 
Last edited:

AndyBees

Top Post Dawg
Joined
May 27, 2003
Location
Southeast Kentucky
TDI
Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
Below is a pic of a modified VSS which is located on the outside of the tranny as Oilhammer described.

Key word "modified" because the gear has been cut off. It was my intent to couple it with the speedometer cable. But, as you can see I was able to "screw" it on the ticker box ......... for my ALH Vanagon project... thus, the reason it is modified.

I hope this visual helps!





 

djd58

Veteran Member
Joined
Jan 20, 2007
Location
Horseshoe bend, Arkansas
TDI
2003 Jetta TDI, 2001 Golf TDI,2011 Golf TDI, 2012 Passat TDI 2014 Q5 tdi
I have replaced stock carriers with LSD's several times, and the gear that drives the speed sensor is behind the right side bearing which is pressed on, as far as my experience the only way to change them is to split the transmission, but then again I throw automatics away in favor of manuals, I have done 4 manual swaps on mk4 TDI's
 

jimbote

Certified Volkswagen Nut
Joined
Jul 10, 2006
Location
spiral arm, milky way (aka central NC)
TDI
Tacoma 4x4 converted to TDI
On both the manual and automatic gearbox bolted to the ALH, the VSS is the same, and is easily removed from the top of the diff.
The VSS drive however, is bolted to the top of the case, and requires removal of a bolt to the clamp to slide out, and that is just the driven gear. The gear that drives that is pressed on to the diff carrier assembly.
So what exactly are you talking about here?
There are also speed sensors at each wheel, the crankshaft, and the automatic trans also has its own speed sensor.
02j and 01m speedo drives are threaded into the case not bolted lke the older 020 ... and the manual and auto speed sensors while functionally the same are different ... 01m auto sticks straight up while the 02j is a 90* job ;).... to the OP if the drive gear on tne trans is bad (01m auto) you need to remove the diff carrier and press the passenger side diff bearing off to replace the gear... this can be done in the car but requires subframe removal ... if it's the driven gear or sensor they can both be replaced in about five minutes
 

jimbote

Certified Volkswagen Nut
Joined
Jul 10, 2006
Location
spiral arm, milky way (aka central NC)
TDI
Tacoma 4x4 converted to TDI
the drive gear (worm) that is installed on the carrier cannot be removed without pressing off the passenger side diff bearing ... the diff has to be removed for this... the diff can be removed (01m auto only) without dropping the trans .. however the subframe has to be dropped, axles have to be removed, axle flanges and bearing retainers for the diff as well as the diff cover .... but it's easier to drop the auto trans ... i can have one out now in under 30 minutes (lots o' practice ;)) ... i did the whole "replace the drive gear in the car" thing in the very first 2.0 beetle i ever worked on years ago .... (i wouldn't do it that way again)
 

motoracer47

Active member
Joined
Jan 19, 2014
Location
New Braunfels, TX
TDI
2013 Passat TDI SEL 2011 Touareg TDI LUX
Sorry to just get back to this thread. Again, awesome info everyone, very informative. I didn't get a chance to look at the car this weekend, had an emergency with work:mad:

Anyhow, all of this info will definitely make it a bit easier to try and figure it out when the time comes.

1 last question. Is the pic below of an 01M transmission?


Again, thanks for the help.
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Yep, that is the ubiquitous 01M in all its glory. A sight I have seen countless times over the last 20+ years. I think I'm getting better and pulling the 02E out now, though. :p
 
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