Funkdariaa

First want to confirm what I'm thinking. Ever since I got this car three and a half years ago and 80kmi ago, ever once in a blue moon, my speedometer would skip up a little intermittently, for just a second. This would cause my cruise to cut throttle, and I would feel it. Sometimes it would do it for one drive so I'd just have to not use the cruise, or maybe for a few days, then not again for months. Sometimes it wouldn't do it for six months, so I dealt with it.

Well today on the way to work my car bucks around a little then starts to decel. Freak out, look down at my gauges, speedometer is sitting at zero. Other than that the car is working fine (for another 25 minutes to work). Assuming it just took the cruise logic fail safe a few seconds to figure out the implausibly signal. The speedometer doesn't work, the cruise doesn't work, the average speed and gas mileage doesn't work. I would assume the odometer stopped accumulating, but I didn't think to pay attention to that. The ECU is allowing a lot more engine braking. Assuming the ECU isn't getting a speed signal so the anti engine brake logic isn't working.

This is all telling me that it's the vehicle speed sensor, but I don't have any experience with this specific failure. Wanting to make sure I'm thinking correctly?

And if so, where do I get one? I usually order from ECS (yeah, I know you probably hate them, but I've never had any issues and they are very close to me), but I don't see that part on their website. I've also ordered a few parts from Pure MS, but I can't find it on their website either. Anyone know who stocks this part?

TIA, Jesse

visintainer [vis]

have you taken out the sensor of the upright and made sure it it clean?

Cerveza

BTW, your logic is correct. I had the same problem, but you should also make sure that the VSS wires are in good condition all the way up to the ECU. I replaced my VSS and it didn't fix the problem. It turned out that 2 wires were severed, somehow and the signal was never getting to the ECU. Luckily the VSS is only like a $10 part and not too hard to change out.

Funkdariaa

Where is the sensor located. I assumed trans/front diff somewhere. ECS said something about the diff, but I've never dealt with this before. Do you know of a pin-out anywhere online for the ECU so I know which wires to look at on that end? I have an early 2000 6 speed (very early, 99 build date, aluminum uprights) if that makes a difference (a box I think).

BTW, I have the Bentley at home, so if this info is easily found on there, just let me know. But I hate trying to find info on that CD sometimes. Is there just a way to look at the whole servie manual instead of having to search?

Where were the wires severed, from the sensor before then went into the engine harness? <~ just guessing most obvious place

I actually just got done talking to ECS. They said they could order it, $43 and if they ordered it today, it should get to them tomorrow, meaning to me in two days (I'm one day out from them) total (maybe 3). But that's still great turn around time. More than $10, but still not bad. I loves me some cruise control (and being able to see how fast I'm going).

If it were the wires and one wasn't just severed suddenly, I would think it might be a little more intermittent before the complete failure. It hasn't done the jerky thing for as long as I can remember, months, maybe a year now. It's been a while. I'm really interested to see if it works for a little while after work today as this happened 30 minutes into my drive to work.

I should just order a vag com for this and so many other reasons.

Funkdariaa

I'm talking about the vehicle speed sensor. Generally speaking, the wheel speed sensors send the signal to the ABS unit (physically separate unit and ECU than the engine ECU) for use by that. That unit uses the 4 wheel speeds to determine it's own vehicle speed. There is a separate sensor that is driven by something in the driveterain (usually geared?)that is sent to the Engine ECU for it signal for the vehicle speed.

I can only assume this is the case for this vehicle without specifically knowing. I had an ABS wheel speed sensor fail (wire broke) two years ago and it did nothing to the engine ECU vehicle speed (from the VSS<~ vehicle speed sensor) as my speedo (and everything else driven by the VSS) seemed to work fine.

The ABS wheel speed sensor are in the uprights, but that is not the sensor(s) I'm talking about here.

visintainer [vis]

i got confused cause etka just calls those senors "speed sensors" thanks for the add. info

Funkdariaa

It's all good in the hood G

Nick Gustas

Black sensor just above the axle flange:
<img src="http://tychl.txf.com/k0something/index.php?picture=113-1307_IMG.JPG&maxx=1024&maxy=768">

Funkdariaa

U roxor! Gold star for you. Doesn't look hard too get to, but is it hard to get out?

PlumSmuggler

have fun getting at it from underneath with the axel in and the guard in place, it's a bit more challenging.

BTW, I bought my new one from PureMS. They shipped it that day; cheap.

Good luck.