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hey guys, this is my first post in hopes of coming to a conclusion, i currently have a 1998 porsche boxster with tiptronic transmission, the following problems are as follows.

1.when in parking the car doesnt stop

2.when in automatic drive car doesnt go to 3rd gear it jumps from 2nd to safe mode with a big kick

3.when left on first gear in manual mode car exhaust sound gets louder, and when letting of the gas does big kick to safe mode

4.when the car is turned on and switched to manual the tiptronic controls only lets me move up to 2nd gear.

i was thinking it was the transmission ecu but it wasnt, i have tried 2 other ecu's one with the exact serial codes as the original (besides actual ecu serial) and still same problem

Might it just be the transmission itself?

if so where can i buy rebuild parts?

and guide on how to.

I really need to get this figured out any advice would be helpful, thank-you for your time :)

Edited by Nivaldo Veliz

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I have two suggestions, perhaps it might be worth checking that the linkage is properly aligned, secondly I have heard of tiptronics working in manual but not in tip mode as a result of a clogged transmission filter. These autoboxes are reckoned to be very reliable so I would look elsware first before considering exchanging the gearbox.

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P0722 (Porsche codes 36 and 90) Speed sensor - signal implausibleTransmission output speed monitoring - signal implausible

P0722 Open circuit(Porsche Short circuit to B+ code 36)

- Short circuit to ground- ATF level not OK- Faulty torque converter- Slipping clutch or brakes

P0722 Open circuit(Porsche Short circuit to B+ code 90}

- Short circuit to ground- ATF level not OK- Slipping clutch or brakes

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does this mean that the sensor itself might be ok? and giving code because of one of those ^ ? also, where would that specific ground cable be at?

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I have had similar issues and may be able to help guide you down this path a little bit. How was it driving before these issues? Any noticeable changes in shifting performance?

As Loren noted, most likely scenario is low ATF, but most people will notice a significant leak if this is happening. Regardless, this is the first and easiest thing to check. If ATF level is ok I would look at your coolant reservoir to see if there is any sign of oil/coolant intermix in it. If so, it will look like a creamy coffee color, or you will see oil floating on top of the coolant. If this is the case then you have a blown ATF cooler which will need to be replaced, followed by seriously cleansing the transmission of all intermix. Hopefully this is not your issue.

Also, check the appropriate pins for correct short and ohm readings both at the transmission (round plug towards the front of the ATF sump pan) and at the ECU. This should confirm if your sensor(s) are out of range. If you don't have these values, let me know and I will track them down and post them. While at the round plug check to make sure that oil/water has not seeped into the wiring.

There is at least one pin in the plug that is for ground, but you will need the pin diagram to find it. I can post this as well if you need it. Alternativey, use a very long ohmmeter probe and attach it to the negative terminal of your battery.

Basically, the code you reference will be issued if the expected wheel speed is not obtained at the given RPM. Once the CPU sees this, it will issue the code and put the transmission into default mode (flash P and 4) to protect the transmission from any further damage. Yes, this could be a mechanical transmission issue, but I wouldn't jump to that conclusion yet.

I am in the middle of rebuidling my transmission after a failed ATF cooler and resulting intermix that demolished the fiber clutches in my transmission. There are several sources for kits for rebuilds, but again, don't jump that far yet!

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If you have a proper scan tool you can read the rpm of the transmission speed sensors but low fluid levels will give bogus readings so that has to be addressed first. You also need to verify the multi function switch is indicating the gear box is in the correct gear. These are fairly reliable gearboxes with two main points of failure is the torque convertor bushing failing causing a oil leak and the coolant control system for the cooler as another.

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ive done some research, its most likely the inductive transmitter on the valve body AKA (output speed sensor)

Edited by Nivaldo Veliz

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Certainly possible. Should be easy to confirm with an ohmmeter that the sensor has the correct value.

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