Pics and write up of VSS Speedo mod?

[zippyslug31]

Thanks for posting the pics above.

Can someone confirm/debunk what is going on in my van...
My van came with factory cruise which has always been difficult to set (I always assumed it was a faulty 'set' switch in the end of the stalk).
Now with my converted van, I can now tell that my mechanic disconnected the 2-wire plug from the back of the speedo and retrofitted a 3-wire that looks very much like the pictures in this thread.

So here's my theory: the factory VSS inside my speedo (the part that should have told the factory cruise to set) is faulty. This part is also failing to tell the pickup (the 3-wire one my mechanic fitted) proper speed thus my system throwing codes.
Does this hold water?

With the pickup removed I can see the small silver disc inside rotate slightly when I spin up the speedo shaft. When I stop spinning the speedo the disc returns to a resting spot.
I understand there are four magnets inside the speedo. How can these be tested and fixed?
_________________
previous:
'80 westy
current:
'90 syncro westy 2.5L subi, triple knob, 16" wheels.
'84 sunroof van, 2.1L motor.

[jordauto]

The existing two wire sensor would have been removed to install the new three wire sensor. The two wire sensors are AC signal generators, which means that they produce AC current. The three wire sensor is a hall type sender, there will be an ignition in wire, a ground, and the third wire is the signal. It will output a frequency that can be tested with any automotive test scope. Check for power and ground at the sensor plug, and signal output at the sensor and at your ECM plug. If those are good your cruise issues may be caused by out of adjustment brake or clutch switch or the vacuum switches at the clutch and brake pedals.

[r39o]

[jordauto]

Yes the signal from the three wire sensor can be split and run the factory cruise and supply the ECM with the VSS signal as well. I have mine running this way and have done others with success. I'm on the road today but if you need the pin outs for the VSS mounted in the cluster let me know and I could take a pic.

[zippyslug31]

Figured I'd give a little input on what I learnt with my van....

I found that in my specific case, the aftermarket VSS that was installed into my speedo was not aligned with the magnetic pulse wheel (driven by the speedo cable).
The only way I was able to find this out was to completely disassemble my speedometer, re-install the VSS pickup in the housing, and observe how far/off the pickup was from the wheel. In my case I was probably a good 3/8" away and off to one side. Clearly the inductive pickup used in my case wasn't strong enough to sense the magnetic pulse from this distance.

I resorted to using a dremel to shave down the mount location in the speedo housing (to get the pickup closer to the wheel) and resoldering the pickup a bit further out (to align it better). Once I did this my ECU stopped throwing codes, ran a ton more stable when slowing to a stop, and now my cruise control works perfectly!

The only down side is disassembling the speedometer. This isn't for the faint of heart since you'll need to remove the old/brittle speedo needle and remove the tiny "watch spring" under the gauge face. Both of these pry off, but with a lot of gentle handling.
Also, resembling the speedo to make it all work perfectly again is requiring me some trial and error.

Just wanted to add all this because I didn't see anybody speak to how the VSS is installed as this matters how well the thing will read back to the ECU. Simply slapping one in the housing is no guarantee it's going to work without some alterations.

Hope this helps others in the future.
_________________
previous:
'80 westy
current:
'90 syncro westy 2.5L subi, triple knob, 16" wheels.
'84 sunroof van, 2.1L motor.

[scobax]

I'm trying to debug a Jetta sourced cruise control/VSS on a friends 2.5 Suby equipped Syncro. I wonder if anybody might be able to tell me the wiring sequence for these Jetta sourced VSS pickups. Here is a photo with what we have:

Can anyone tell me which wire should be signal, which one is positive and which is negative? We are trying to verify if it was wired correctly by the original installer.

If properly wired and powered up, how would one measure the output signal?

Any help would be greatly appreciated.

Scott
_________________
87 Syncro Westy w/ Suby 2.5
RIP: 2.1 WBX. You were a good dog 'ol feller

“The word adventure has gotten overused. For me, when everything goes wrong, that's when adventure starts” -Yvon Chouinard

"It's not expensive, its priceless" -Unknown

[0cean]

I could use some help with a Subaru three wire vss to two wire connection for the Vanagon. Anyone done this before?
_________________
I'm not a mechanic, I just play one on the internet

Cluster Rebuild:
http://www.thesamba.com/vw/forum/viewtopic.php?t=569920&highlight=

Left for Dead the Resurrection Story Build:
http://www.thesamba.com/vw/forum/viewtopic.php?t=613669
(Number of Different Donor VW Vans Body Parts Used: 12)
(Number of completely different vehicles parts used: 3)

[t3 kopf]

For a little clarification, does this mod only work with speedometers from vans that had cruise control or does the pickup just feed off the accelerator cable?
_________________
'90 Carat w/ '95 phase 1 EJ22 OBD2 conversion

[syncrodoka]

Maybe information from this thread will be helpful.
http://www.thesamba.com/vw/forum/viewtopic.php?t=480072

I only know for sure that they will fit the later style snap on speedometer with CC knock out in the back

[t3 kopf]

I had read that thread as well. What im trying to understand is if the sensor is reading off of the accelerator cable or if the factory cruise control equipped vans had some sort of circuitry in the speedometer that the sensor is reading
_________________
'90 Carat w/ '95 phase 1 EJ22 OBD2 conversion

[syncrodoka]

No it doesn't read off of the accelerator cable or speedometer cable. There is a metal disk inside of the speedometer that triggers the pickup.

[t3 kopf]

Thanks, that's what I was wondering. looks like this one wont be an option for me then
_________________
'90 Carat w/ '95 phase 1 EJ22 OBD2 conversion

[connorsvw2]

The 2wd speedometer trigger for cruise control is a magnetic rotating disc and generates 4 pulses per wheel revolution. Subaru ECU expects 5 pulses per wheel revolution, so you are off enough that the ECU thinks you are going ?slower than you are, which in a 2wd isn't a problem unless you are using a Scanguage to record speed. This is why the SmallCar CV joint sensor has 5 slots.

The syncro cruise control/speedo magnet is different, as I recall, and doesn't work well with this type of speed sensor. I can't recall the issue now, but I seem to recall the ECU thinks you are going too fast and can trigger a limp home mode at higher speeds.

I've used this speed sensor in a home brew application with a Hall effect chip and 3 wires for the past 8-9 years, and it works great. Don't know about the cruise control question or the VAG sensor though.
_________________
'85 Westy Wolfsburg camper/2002 2.5 Subaru since 2003.
'85 GTI 1.8L 1-owner 8v-gave up on 9A 2.0L 16v transplant. Keeping her stock!
'99 Passat 1.8T Variant-AKA "The Money Pit". Still limping along...
'09 Subaru Outback XT 5-speed, 245 hp rocket (wife's car)

[syncrodoka]

[walkingupstream]

I just wanted to add something about a VSS issue I recently overcame and what I found:

I have a GoWesty Speedo-mounted VSS (replica of the Jetta VSS). In my Subaru conversion, I got code p0505 (generic idle system error).

Very, very, very long story short- I finally determined that the length of the VSS nipple just wasn't long enough to register the magnetic field.

The depth of my VSS port is 16mm, the length of the GoWesty VSS was 11mm. Someone somewhere said it needs to be within 4mm. I cut out some of the plastic on the VSS itself (and just a little in the speedo to accomodate the wires), gained 2mm, and now it's working.

Hope this helps someone someday.

[wiskas]