16885 Vehicle Speed Sensor - drivin me crazy!

[v12bug]

guys,

I have a 2002 New Beetle 1.8T, owned from new. I have had an issue for some months now with the speedo, as below:

-------------------------------------------------------------------------------
Address 01: Engine Labels: None
Part No: 06A 906 032 FT
Component: 1.8l 5VT NB MT G 3996
Coding: 00001
Shop #: WSC 00066

1 Fault Found:
16885 - Vehicle Speed Sensor: Implausible Signal
P0501 - 35-00 - -
Readiness: 0000 0001
-------------------------------------------------------------------------------

I have:

1. replaced the vehicle speed sensor.
2. bought a brand new instrument cluster, and re-programmed immob, keys etc etc... (had to anyway, as immob packed up)

anyway, problem persists... eratic fuel gauge, and speedo NOT working!

I believe the next step is to trace the blue/white wires? which feed the vehicle speed signal..

can anyone give me some pointers pls?

btw. I have tried to measure the vehicle speed using vag-com but cannot find the 'Acceleration Measurement' block?

http://www.ross-tech.com/vag-com/tour/m-blocks.html

anyone know which group to look for on a 1.8T ?

cheers

[Dana@Ross-Tech]

Have you removed the plastic drive gear from the transmission and inspected it for damage? This drive gear should be threaded into the trans and the VSS threads onto it.

If it looks okay, you could lightly chuck the end into a drill and turn it at a very low speed. If you have VCDS hooked up with the key on you should see a VSS reading in the Engine, Abs and Instrument cluster. You could have an assistant watch the speedo ion the dash to see if it works.

VSS readings are usually found n MB 5 from the Ecm. If you post the complete Auto-Scan we can see what cluster and Abs modules are installed.

[v12bug]

hi, thanks for the reply.. apologies haven't had a chance to try till now..

ok, so I firstly tried MB 5 from the Engine Control Module.. vag-com read NO vehicle speed whatsoever whilst driving...

so, I removed and inspected the 'plastic drive gear' for damage.. all looks fine..

lastly, I tried attaching the VSS on the end of a drill chuck and very slowly driving the VSS (even in both directions).. Still No reading on the speedometer! !..

I can see the three wires (blue/white/brown) that send the signal from the VSS and all looks ok from below the engine bay.. I have even cleaned the contacts.

So, next step I guess is to start tracing the wiring. Any pointers guys on best place to start, and / or any other ideas?

fyi, below is a full vag-com SCAN, if it helps..

thanks guys
==========================

VCDS Version: Release 908.2
Data version: 20100326

Chassis Type: 9C - VW New Beetle
Scan: 01 02 03 08 15 17 19 22 26 29 35 37 39 46 54 56 75

-------------------------------------------------------------------------------
Address 01: Engine Labels: None
Part No: 06A 906 032 FT
Component: 1.8l 5VT NB MT G 3996
Coding: 00001
Shop #: WSC 00066

1 Fault Found:
16885 - Vehicle Speed Sensor: Implausible Signal
P0501 - 35-00 - -
Readiness: 0000 0001

-------------------------------------------------------------------------------
Address 03: ABS Brakes Labels: 1C0-907-37x-ESP-F.lbl
Part No: 1C0 907 379 E
Component: ESP FRONT MK60 0104
Coding: 0019970
Shop #: WSC 00066 000 00000

No fault code found.

-------------------------------------------------------------------------------
Address 17: Instruments Labels: 1C0-920-xx0.lbl
Part No: 1C0 920 920 FX
Component: KOMBI+WEGFAHRS. M73 V08
Coding: 05412
Shop #: WSC 00000

No fault code found.

-------------------------------------------------------------------------------
Address 19: CAN Gateway Labels: 6N0-909-901-19.lbl
Part No: 6N0 909 901
Component: Gateway K<->CAN V082
Coding: 00006
Shop #: WSC 00066

No fault code found.

-------------------------------------------------------------------------------
Address 46: Central Conv. Labels: 1C0-959-799.lbl
Part No: 1C0 959 799 F
Component: 2Q Komfortgerát HLO 0004
Coding: 00064
Shop #: WSC 00066

Part No: 1C1959801A
Component: 2Q Tõrsteuer.FS KLO 0002

Part No: 1C1959802A
Component: 2Q Tõrsteuer.BF KLO 0002

No fault code found.

-------------------------------------------------------------------------------
Address 54: Rear Spoiler Labels: 1C0-959-733.lbl
Part No: 1C0 959 733 B
Component: Heckspoiler 0002

No fault code found.

End ---------------------------------------------------------------------

[Dana@Ross-Tech]

I would check the wiring diagram for that vehicle but the 3 wire VSS circuit typically has:
- 12V power (likely from a fuse)
- Ground, I'm going with the Brown wire
- Signal wire

You could verify the power and ground. The VSS and Cluster were already replaced so the next suspect may be the signal wire.

Did the Fuel gauge and the Speedo quit at the same time? If they did I would also check the power and grounds to the cluster.

[v12bug]

thanks Dana for your reply.. you're probably right.

- 12V power (white wire, as you say, likely to be from a fuse)
- Ground, (most probably Brown wire)
- Signal wire (remaining Blue wire)

hhmmm, interestingly, as you mention above, the fuel gauge and rev-counter (tacho) were working on the old cluster unit, just NOT the speedo, before it packed up. So, one would think then that the 12v (white) wire, is good, and probably the ground (brown) wire also.

As the speedo is still NOT working on the new cluster, but everything else (fuel gauge / rev tacho / power backlit) it stands to reason that the likely culprit is indeed the VSS Signal (blue) wire.

So, does this signal (blue) wire go directly from the VSS to behind the cluster? or via something else?

Ideas anyone

[v12bug]

ok. would you believe it guys?..

after all of that, guess what.. it was a damn fuse in the side panel that had blown, which i swear i had checked before!!! anyway, the speedo is working again, thanks all

anyway, now onto another couple of issues..

1. reverse light is constantly on. Replaced reverse light switch on side of tranny, to no avail.

2. When I turn on the rear defroster / defogger, the 7.5A comfort system fuse blows. Also the cruise control stops working as well as the outside air temp indicator stops working.

I now have NO faults codes on the vehcile at all, but the above two issues persist. I believe both issues relate to a 'grounding / earth' issue?

I suppose I could backprobe the connectors, but need some advice on what to look out for in terms of readings etc. and / or anything else?

any advice would be appreciated.
many thanks all

[armandjones82]

Try to ask out other options if the speed sensor is still acting out to the experts in that field, or in that case, to mechanics or to car dealers. Sometimes, the old convention way can be effective in order to check out what really happened to your speed sensor or your car as a whole.