ABS sensor revisions/compatibility

[strtnz]

I had to replace the wheel hub assembly on my 2000 986 S and replaced it with a 2002, which has a different ABS sensor connector. I tried to remove the correct sensor from the old hub but it was rusted in there and snapped out.

I've cut the connector off the older, correct sensor, and I plan to just try to splice this connector onto the newer revision as I'm worried about snapping if I try to replace the entire unit.

Has anyone tried this before? It's a simple two-wire system that I assume uses Hall-effect magnetics and so simply closes/opens the circuit when the marking passes the sensor, but I'm just curious if anyone has knowledge which proves this won't work.

[JFP in PA]

Get the right one for the car............

[strtnz]

Originally Posted by JFP in PA

Get the right one for the car............

Thanks for that very unhelpful reply.

[JFP in PA]

Originally Posted by strtnz

Thanks for that very unhelpful reply.

Not all of these systems are the same, different years used different number of teeth on the tone rings in the hubs which will send erroneous information to the system control network and result in codes that can NEVER be cleared. This is why the sensor connectors are different, to prevent installing the wrong style on the car.

Get the right one for the car......................

[strtnz]

Originally Posted by JFP in PA

Not all of these systems are the same, different years used different number of teeth on the tone rings in the hubs which will send erroneous information to the system control network and result in codes that can NEVER be cleared. This is why the sensor connectors are different, to prevent installing the wrong style on the car.

Get the right one for the car......................

Ok, that's extremely helpful so I don't know why that reply wasn't the first one. Thank you.

Edit: but if the tone ring has a different number of teeth I'd need to change both that and the sensor itself to not risk those permanent codes... Right?

[JFP in PA]

Originally Posted by strtnz

Ok, that's extremely helpful so I don't know why that reply wasn't the first one. Thank you.

Edit: but if the tone ring has a different number of teeth I'd need to change both that and the sensor itself to not risk those permanent codes... Right?

And you would need the appropriate ABS control module, as well as the matching DME software to accept its presence, and these would need to be coded to the car, but then the other three sensor/hubs would fault because they have become mismatched.

It is VASTLY easier and cheaper to simply use the correct parts in the first place.

And, my first response is still the correct one............

[piper6909]

Looks like the sensors may send a different signal entirely. It could be your 2000 has a passive sensor and the 2002 has an active sensor. One sends A/C current in a sine wave while the latter sends a digital square wave. If that's the case, you'll get an error code regardless of the tooth count on the ring. So, you're stuck with having to get the correct sensor.

Here's a helpful video:
https://www.youtube.com/watch?v=LC3jCyHjWqo&t=155s

[strtnz]

Originally Posted by piper6909

Looks like the sensors may send a different signal entirely. It could be your 2000 has a passive sensor and the 2002 has an active sensor. One sends A/C current in a sine wave while the latter sends a digital square wave. If that's the case, you'll get an error code regardless of the tooth count on the ring. So, you're stuck with having to get the correct sensor.

Here's a helpful video:
https://www.youtube.com/watch?v=LC3jCyHjWqo&t=155s

Very helpful, thanks for sharing!

[strtnz]

Originally Posted by piper6909

Looks like the sensors may send a different signal entirely. It could be your 2000 has a passive sensor and the 2002 has an active sensor. One sends A/C current in a sine wave while the latter sends a digital square wave. If that's the case, you'll get an error code regardless of the tooth count on the ring. So, you're stuck with having to get the correct sensor.

Here's a helpful video:
https://www.youtube.com/watch?v=LC3jCyHjWqo&t=155s

Perfect. Then I can test each sensor's output voltage and if they're in the same range I'll have a go at splicing, if they're in different ranges I'll know I need to buy an original sensor.

[strtnz]

Originally Posted by piper6909

Looks like the sensors may send a different signal entirely. It could be your 2000 has a passive sensor and the 2002 has an active sensor. One sends A/C current in a sine wave while the latter sends a digital square wave. If that's the case, you'll get an error code regardless of the tooth count on the ring. So, you're stuck with having to get the correct sensor.

Here's a helpful video:
https://www.youtube.com/watch?v=LC3jCyHjWqo&t=155s

Very helpful, thanks. I'll try to measure the signal voltage but it seems inductive type need a supply voltage so that may not be so simple, but I think it's worth a try to see if they're both in the same range.

Given the other comments I'm not expecting them to match up, but it's a fairly easy step to do anyway.

[Marc_986]

Indeed, early sensor model is inductive, later model is hall. Different sensor, different electronics altogether. Splicing is no use.

The early style sensor is used on the ABS5.3 units, the newer ones on the ABS5.7.

Teeth should be the same.

So you could also swap the ABS unit out to a 5.7 and swap the front sensors ;-) Oh, that wiring has many differences as well, most obvious ones being the connector on the ABS and that speed is send over CAN instead of a dedicated VSS signal.

For you, by far the easiest is to get a correct sensor. You could get a used one, but most dismantlers keep them in the wheel carrier for obvious reasons. I managed to get some wheel carriers for under $50 which included the sensors. Cheaper than a new sensor it seems

[strtnz]

Originally Posted by Marc_986

Indeed, early sensor model is inductive, later model is hall. Different sensor, different electronics altogether. Splicing is no use.

The early style sensor is used on the ABS5.3 units, the newer ones on the ABS5.7.

Teeth should be the same.

So you could also swap the ABS unit out to a 5.7 and swap the front sensors ;-) Oh, that wiring has many differences as well, most obvious ones being the connector on the ABS and that speed is send over CAN instead of a dedicated VSS signal.

For you, by far the easiest is to get a correct sensor. You could get a used one, but most dismantlers keep them in the wheel carrier for obvious reasons. I managed to get some wheel carriers for under $50 which included the sensors. Cheaper than a new sensor it seems

Where do you find all this information from? I'd love to be able to have all this sort of knowledge on tap!

[Marc_986]

I happen to have done a bit of research on the ABS systems for my project car. I'll be swapping ABS 5.7 into my early ('97) boxster.

But to answer your question;
- This forum has a lot of information. Not always in full detail, but at least giving direction
- Bentley manual
- Porsche parts catalog