Alan G.

I have my C4 apart for a 222,222 mile overhaul.
Its great to have another option to PCNA.
The whole PDAS works fine, but replacement with these sure makes the $$
go farther.

Great job, Thanks

Alan

Canneryrow

Further to my earlier post, the accelerometers in my '89 targa have been removed, taken apart, thoroughly cleaned and replaced in the car. We took the extra precaution of switching the two around so that if the same one failed it would show up as another fault code and if the switched one failed that would indicate that there was another problem.

The car's been out on what the garage describe as a 'long and at times, vigorous', test drive and they report no dashboard warning light or fault code.

So, it seems that the problem has been solved for now. However, the next time one fails, I'll be on the phone to John in Cambridge to order a couple of solid state units.

Goughary

I know these things are expensive, but just to put it out there...a faulty accelerometer in a c4 can cause a bad crash. Keep in mind that under hard braking you can lose your brakes (or what feels like it when they begin to set off the abs early), your diff locks can go full lock and create massive under steer in the middle of a hard corner, etc....so if you think you have an issue, take it easy till you absolutely know you don't.

Just putting it out there. I had too many close calls before switching to these. No fun.

Canneryrow

A fair point, Goughary. I'll run the car as is for the summer and then think about switching to the solid state units over winter. And of course, if and when a fault light comes on, I'll call Cambridge ASAP.

Canneryrow

Well, it seems that the fault has returned. This time twice yesterday. To and then from the "Classics at the Castle" meet at Hedingham castle. Both times on long, sweeping A road bends. The warning light cleared when I stopped and restarted the car.

My car's due to go into JAZ to have a couple of minor things done. While there, they will check the accelerometers once more. Last time, they disassembled and cleaned the units. Then, they switched them over to ensure that if it was a single sensor that's gone, then the fault code would switch too. I assume that it is the original faulty one that has gone once more.

Whichever one has gone, I really have to buy some solid state units from John. Enough is enough. Once JAZ confirm that it's the accelerometer that's at fault, my order will go in.

Canneryrow

A hat trick of posts.

Accelerometers purchased and fitted. Hopefully, that will put paid to the alarms.

Andy964CH

Hello everyone!

I am new to rennlist and look for some ideas and hints concerning my 964/4 accelerator issue.

The braking issue described above was exactly occurring on my side as well. I had some "near hits" when my ABS system stopped working at full stop on the last couple of meters. You can notice it not only through the fact that the car is kind of slipping, but also that the braking pedal starts to push against you suddenly on that last couple of meters. Someone mentioned here in this thread that a warning lamp pops up or that it is possible to read-out accelerator issues with the BOSCH hammer. As far as I have observed, both is not the case. The accelerators will just corrode slowly and stop working and there is no way to detect it until it is too late... However, A. Streather mentioned in his 964 handbook, that there exists a special ABS test and diagnostic system capable to read non-plausible signals. But this tool is rare and I have never met one who has it.

So what I have done: I switched both units, but the braking problem remained. Then I put out both, cleaned all the dust and dirt attached to the magnet and reinstalled them.
Result: One still defect, the other one seems to be ok, as I can't reproduce the ABS braking problem.

So I have been in contact with John from JDSPorsche now and will order replacement soon. The only remaining question I have to you guys: Would you suggest to replace both to have consistent sensors and functionality or would it be sufficient to replace just one sensor?

Thanks in advance!

Andy

Andy964CH

Hi everyoneCheers

Joe J

Just installed the

Console wiring marked and can see original sensors, also marked position if someone ever wants to put them back.

New JDS sensors in, even came with shorter screws.
JDS sensors in my 964 C4, a mechanic swapped the positions of my old ones and it made the PDAS light stay off a little longer, but rough roads would set it off again, finally got time to replace the original ones with these solid state ones. I’m a happy to say, no warning lights. Console is fun to take apart, tip, mark the switch panel wires and bundle ones that go either above or below the console bracket. A mechanic in Atlanta says with small screwdriver wrenches, the replacement can be done from the passenger side access port, I was not that lucky and opted to pull the console since the longitudinal (assuming most forward one) sensor was under a fuse receptacle.