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Tiptronic problem / questions

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In the process of troubleshooting a Tiptronic transmission issue (2000 Boxster Tiptronic, 92,000mi), of which you can read the history on this post: http://www.renntech.org/forums/topic/28941-serious-2000-boxster-problemplease-help/

To summarize, after losing all power to the wheels on Sunday, and the indicators flashing "D - 4", had the car towed home and I changed the ATF (following all proper procedures...I'm unfortunately quite familiar with that process). Still no power to the wheels (car is on jack stands, rear wheels are off the gound), and no "kick" into gear that I can normally feel when putting it into R or D. After reading some posts here, I unplugged the battery overnight to reset the ECU (seemed to have fixed others with similar problems). After replug on Tuesday, I had some power in D, minimal to no power in R...progress at least! Try again yesterday (Wednesday) and have good power in D (seemingly normal), more power in R (possibly normal), and feel the normal "kick" into each gear...promising! Switch over to M and no power...Arrrgh! Based on this, I believe this is all being caused by an electronic problem in the transmission control board(?).

Not being very familiar with the Tip, I have what may be some elementary questions based on my experience yesterday:

1. In D, without the brake pressed and no gas pressed, both wheels initially spin (speedometer shows 10mph), but after ~30s the passenger wheel stops turning, while the driver's side wheel continues (speedometer still shows 10mph). Normal? Or is there a problem with my Diff?

2. In D, accelerate to 30-40mph, and car shifts into 3rd, sometimes 4th gear very smoothly, seems normal, both wheels spinning.

3. In N, without the brake pressed and no gas pressed, both wheels spin forward (speedometer shows 6mph), same thing happens after ~30s as mentioned in Q1. Normal?

4. In M, no power to wheels as mentioned above, but speedometer shows gradually increasing speed from the 10mph it showed in D, even though both wheels have stopped moving. WTF???

Since I had power in D, took it off jack stands and drove it out of the garage, made a quick loop at the end of the driveway and drove it back up and into its spot in the garage. My driveway is reasonably steep (~15deg) and everything seemed fine in that 1/10th of a mile. Waiting for a Durametric to arrive before I drive it too much more to see if it tells me anything important. I'll post codes as soon as I have them.

Thoughts? Ideas? Help!?!

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  • 2 weeks later...

Got the Durametric yesterday. Here are the Tiptronic codes:

91, P0717: Stall speed, transmission input

62, P1715: Front right / front left

55, P1710: Speed signal - DME control unit

I plan to chase 91 first, but I forgot to bring home my ohmmeter yesterday. One question, where is the 16 pole transmission connector that the manual refers to? Is this the one in the front luggage compartment? If so, any suggestions on getting readings between the Tip control module in the rear compartment and the ABS control module in the front compartment (that's a long way!)? I think 62 and 55 may just be related to running the car while jacked up.

Any other ideas?

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P0717 (Porsche codes 91 and 92) Stall speed, transmission input - signal implausible

Gear monitoring, transmission input speed - signal implausible

Possible causes:

- Open circuit - Wiring

- (Porsche Short circuit to B+ - Transmission input speed sensor code 91)

- Short circuit to ground - Torque converter

- ATF level not OK - Transmission

- Slipping clutch or brakes

- Faulty torque converter

P1710 Speed signal, front right -. signal implausible

P1715 Speed signal, front left - signal implausible

Possible causes:

- Discontinuity/short circuit to ground - ABS control unit

- Short circuit to plus - Tiptronic control module

- Wiring

Of course, check the ATF level.

Also, did you get any ABS faults? It gets the speed signals from the ABS sensors.

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Excellent, thank you!

I replaced the ATF fluid as my first reaction, so I am sure it is correct.

The ABS light is now on, but there were no faults stored. This is the same thing that happens when I get the car smogged. The ABS light will go off once I drive around a little, but since I can't drive it right now it is still on.

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This is a real shot in the dark but I'm mentioning it because it happened to me. When I had my OEM brakes, on my '99 Boxster, upgraded to the Big Reds the rear axle knuckles had to be upgraded to 2001 S parts so the emergency brake mechanism worked and the calipers could be mounted. After the work was done the ABS light came on and after some head scratching the problem was the sensor that determines axle rotation was not reading properly. In my case it was because the sensor, in the new knuckles was calibrated to read the larger S axle and was too far away from the smaller axles of my non S. It was fixed by fabricating a new bracket for it so it sat further down in the knuckle. I only add this to give you a heads up that you may need to check the sensor to see if it is working properly. It is located on the passenger side axle.

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Thank you for the information on the axle rotation sensor, I will definitely keep that in mind.

Loren, I have not cleared the faults yet because I wanted to check on some of these things first. Now that I have the information, I will clear the codes tonight and see what happens. I am a little scared to drive it around too much, fearing that I may damage something more or I may get stranded again and have to tow.

Could it really be that simple?

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Got the Durametric yesterday. Here are the Tiptronic codes:

91, P0717: Stall speed, transmission input

62, P1715: Front right / front left

55, P1710: Speed signal - DME control unit

One question, where is the 16 pole transmission connector that the manual refers to?

Any other ideas?

You should start inspecting the main connector located on the transaxle. Water can migrate into the sensor corroding the pins and the odd time transmission fluid can be drawing through the connector into the vehicle wiring harness causing issues. Pull back the weather pack grommets and carefully inspect.

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Reset the codes, and the following came back up:

91, P0717: Stall speed, transmission input (same as before)

36, P0722: Speed sensor (this is new)

Per Service Manual to chase DTC 91 I ohmed pins 16 and 44 on Tiptronic control module connector. It appears to be way out of spec at 42kOhms (should be 230-300Ohms). This points to the sender for transmission input speed.

To chase DTC 36, I ohmed pins 14 and 42, which appears to be in spec at 0.9kOhms (spec is 0.8 - 1.2KOhms). So the sender for transmission speed appears to be ok.

The previous codes DTC 52 and 66 have not reappeared. Howerver, there is no power to the wheels now at all. After revving up pretty high and getting no movement the P/4 flashing starts, indicating the fault.

Is there a good place to connect to B+ in the rear luggage compartment to check the other values recommended by the service manual?

Is there anything else I should check before replacing the input speed sensor?

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Ok, yesterday I got to the 16pin plug where it connects directly into the transmission. Since it was the first time I had removed that plug it took some fiddling to get it off, but now that I have put the plug back on I believe the plug may not have been fully attached/engaged into the receptacle. I ohmed the pins to check the speed input sensor directly on the socket to the transmission and, low and behold, the value was in spec (260ohms). I also pulled back the rubber on the plug at the transmission and there is definitely some oil present. I did not clean it with anything other than shop towels so far because I didn’t want to damage any of the electrical connectors with a substance that may corrode it, so I will get some good stuff to clean it up soon. I also confirmed continuity between the appropriate pins on the control module plug and the 16 pin connector plug.

After cleaning what I could from the plug, I reattached it, started up, etc. Initially, the car seemed to behave the same (poorly), weird movement in Reverse, slow to little movement in Drive. I then cleared all the codes that were stored and tried again. With the wheels elevated the car seemed to engage Reverse and all gears properly. I got it into 5th gear and let it come back down to 2nd gear on its own…all very smoothly.

So, I think I’m down to two possibilities since the sensor appears to be ok. Either the connector was loose and/or had oil present making the communication between the tiptronic control module and the transmission whacky; or, there is a problem with the TC (although I have not gotten any codes for this yet). Of note, after resetting the codes and the car seemingly performing normally, the code 91 / P0717 did not reappear. I got the 55/62 codes again, which I believe to be normal since the car is elevated.

Next step will be to properly clean the plug, drop the car, reset the codes and test drive. If there are any other suggestions please let me know and I will let you know what happens once I try to actually put the car on the road.

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Oil in the connector and wiring harness disturbs communication Tip. versus control box, with sometimes permanent damage, check the source of the leak and repair ASAP is my advice.

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I agree with RFM. You need to fully clean the connector and replace the ribbon cable for the valve body as the sealing properties of the electrical connector have failed. Oil can migrate up the wiring harness and into the transmission ECU causing damage which could require replacement so inspect the ECU connector also.

If you have PSM, operating the vehicle on a lift will also display odd transmission operating so it's recommended to clear all fault codes in all modules and drive the vehicle to evaluate.

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  • 3 weeks later...

Update: replaced the ribbon cable, replaced the ATF, got everything going and car operated good on test drive for ~20min then ran into the same problem again...no power. Seems to me that the clutches aren't engaging properly, but I'm still not sure if this is an electrical problem or a mechanical problem because things seem fine for a while, then go kaput. The magnets in the ATF pan had almost no metal particles on them. It had been suggested that these problems could be related to when the ATF temperature is higher, so I waited to test drive until the ATF temp was high (90-98C range). Also noted the ATF temperature was in the same range after the test drive. Same codes as before...36 (P0722) and 91 (P0717).

Could the Tip ECU just be bad? Long shot, but does anyone happen to have one I could swap in to see if anything changes? The manual doesn't say this is a potential problem for these codes, though.

A few things stood out to me on this go-round:

The internal ATF filler cap was detached when I removed the sump pan...probably did that when I refilled the ATF previously (woops!). Anything related to that which could cause these problems?

The ATF had some dark "streaks" in it, but overall was normal color. However, I've never seen these dark streaks before in the ATF, and I have drained/replaced it several times over the past year.

When I first backed out of the garage Reverse was acting weird...with gas pedal pressed it was intermittently surging and didn't seem to have the usual torque without any gas applied. It seemed to correct itself after a few minutes though. Shifting through the gears while driving was very smooth...until the power started to fade. Total buzz kill because I thought it was fixed!

I'm stumped. Short of dropping the tranny and taking it apart, I'm not sure if there is anything else to check.

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  • 1 year later...

Just posting some follow-up on this issue. Finally got the time to drop the transmission and open it up. Found some really good tutorials on this on youtube and the ZF repair manuals are pretty easy to find online. Basically, all fiber clutches are corroded, flaking, nasty. Most of the steel clutches are pitted and corroded. Unfortunately, the intermix caused some serious damage inside! I have replaced all fiber and steel clutches as well as all seals, o-rings, etc. that come in the overhaul kit from ZF. I am waiting for a couple of bearings and races that have been hard to find. Sent the torque converter for rebuild just in case. I am hoping to have it all back together within the next few weeks to see if there is any life, but I should essentially have an entirely rebuilt transmission by the end of all this. I hope to report something (positive) in the next few weeks!

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  • 1 month later...

Work is complete and the Boxster is back up and running! I am (obviously) not a transmission expert so going through something like this for the first time has come with many valuable lessons.

1) It is likely impossible to recover from an ATF intermix issue without removing the transmission and completely draining the torque converter as soon as you notice the problem. Had I done this initially, I may have been able to save the transmission before having to do a rebuild. For me it is a bear to get the trans in and out, but for those with better tools and equipment this is a must and likely would have saved me tons of time and money on this project.

2) If your tiptronic is slipping or thumping into gear, check your ATF immediately! At least confirm that there is no intermix and confirm correct amount is in it.

3) It is amazing how much damage the intermix caused to the internal components of the transmission. After seeing them it was obvious that the mechanical damage was causing my issues, not all the electrical stuff I was hoping it would be and that I spent months fiddling with.

4) If you do your own work 90% of the time anyway, don't ever trust a shop with a menial task like changing the serp belt. More things can go wrong than you could ever imagine!

So, all in all, this is the cost to repair:

ZF Master Rebuild Kit (o-rings, seals, gaskets, steel clutches, fiber clutches, etc.): $900 from the CTSC (comes in three separate kits: overhaul, steel, and fiber)

Torque converter rebuild: $340 from europeantransmissions

Valve body rebuild: $420 from Valve Body Express

Filter: $35 from Pelican

11L Pentosin ATF (~9L actually used): $132 on Amazon - this is a steal by the way, this stuff is $19/L on Pelican

3 tapered roller bearings: $42 from Autozone

New ribbon cable: FREE from a friend of a friend of a friend

Total: $1857 and about 6 months of my tinkering

Yes, I could have bought a rebuilt transmission for about $2800, but I wanted to learn!

I've driven about 50mi on it so far with zero issues (at least transmission related). I passed smog yesterday so looking forward to getting it back on the road full-time within the next couple of weeks.

I do have a small engine oil leak that is new, so I am assuming this is a result of the engine not being run for a year and some seals hardening or something. I haven't traced it yet, but I know it wasn't there before.

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