Anyone know of a 2000 VSS speed sensor adapter to 1998 computer?

[crazyace]

Just had a ruff time with a transmission replacement in 1998 windstar, It now has a trans from a 2000, but the newer VSS is a Magnetic pickup where the old VSS was a gear reduced.
When the VSS is connected it looks to be getting about 5+- times the pulses that it should be.
So when driving near 20mh, the gauge reads close to 100mh, and the computer starts cutting the gas down. So, its disconnected and has issues getting out of 1st gear. Computer thinks it's not moving as it's not letting it shift into 2nd. Once, it's in 2nd it's good to go.
I know of a few IC chips that can cut the signal pulses in half and then in quarter. If I can get it to say 70 when I'm only going 56 i'll be . Because cruse control will work again, and my lead foot won't be collecting tickets .
Anyone know of a 2000 VSS speed sensor adapter to 1998 computer? or what the voltage/current levels are on the signal cable?
Thanks.

[Windstartled]

Hmmmm... that's a tough one. If the 95-98 VSS is physically different from that of the 99-03 Winnies and does not operate on the same principle then the computer needs to be instructed on how to manage the data it is receiving from the VSS. I don't know if it is possible to reprogram an older computer to handle data from a newer sensor but it's worth asking around.

"VSS" is somewhat of a misnomer at Ford because it doesn't sense the vehicle's speed, that task is actually performed by the rear ABS sensors, which feed both the VSS and the speedometer. The VSS, as far as I could tell from reading the appropriate sections of the original Ford shop manual, monitors the speed value obtained from the rear ABS sensors and sends this data along with certain transmission parameters to the computer which then processes the data and manages shifting accordingly.

At least that's how it works on the 99-03 models. From your description of speedometer issues you appear to be dealing with a bad communication between the VSS and the rear ABS sensors. If I were you the first thing I'd try would be installing 99-03 ABS sensors and see what happens. The sensors are cheap so the financial risk to you is very low.

[Windstartled]

Been reading up a little further about this and it appears that in '99 Ford began using the rear abs sensors as the source for vehicle speed data on the Windstar, prior to that they were using the VSS for this purpose. VSS computes speed based on transmission RPM with magnetic sensors instead of optical like ABS. This actually means that the "VSS" on 99-03 Windstar is not really a VSS but a TSS (transmission speed sensor) which is useful for shifting management but cannot provide valid vehicle speed data to the speedometer.

If I were to make a guess as to why your speedometer goes berzerk I'd say it's because it is being sent optical data, a format which it cannot process correctly. Even if you could install a 98 VSS on a 00 tranny it still wouldn't work because the transmission does not have the required magnetic sensors anymore.

I don't know if there is a solution for this situation but if there is one it is likely to be software based.

[tomj76]

I doubt that there is a "right way" to do this. If the pulse train is indeed at a much higher rate, then you'd need a "divide-by-n" counter.

A better approach might be to modify the VSS, by removing teeth (if magnetic), or blocking some of the openings (if optical).

[wiswind]

I suspect the the "exciter" part of the setup is inside the transmission and the sensor is just the "pickup" part, which would make messing with the exciter part difficult.

My '96 had the "gear" type, so I'm not real familiar with the newer style.
Unless you can see a moving part in the part that presses down into the transmission body, then you have pickup (looking at the wheel speed sensor.....you have a gear like "exciter ring" that creates a signal each time a "tooth" of the gear passes the magnet inside the "pickup" part)......The vehicle speed sensor will work in much the same way.

[Windstartled]

There has to be a way to do this, surely the OP is not the only owner of a first-generation Windstar to install a transmission taken from a second-generation model. Basically the mechanical aspect is the same, it's the electronics that differ. Lots of driveway mechanics have to deal with new parts whose electronics don't agree with the ones in place, and there is a significant presence of aftermarket gizmos designed to make things work. There may be one for this particular application because the migration of the source of vehicle speed data gathering from the transmission to the wheel speed sensors is an industry-wide trend, it is not specific to Ford. What the VSS sends to the main computer is still the same: data used by the computer to manage shifting. What the VSS on second-generation Windstars does not do anymore is supply speed data to the instrument panel, this it gets from the rear ABS sensors.

Regarding the mechanics of the VSS itself, based on pictures it is similar in both generations, it's how they send data that isn't.