Car model: 2011 Porsche Spyder
Symptom:
So far I’ve only driven it up and down the driveway but there is currently no alert posted. I did hear some mechanical noise at times when selecting between D/N/R. This appears consistent with what would occur during a “stage 1” overtemp.
Hooking up the Durametric did reveal one PDK related code:
PDK Gear Selector – PDK GS
1802: Shift/keylock solenoid position implausible
Cleared it and it did not immediately return. Not convinced this is related to the overheating issue the previous owner experienced. Could be an artifact of the car sitting, being towed and perhaps low/disconnected battery. If it returns I’ll of course have to give it some attention but for now I’ll focus on the overtemp issue. First step will be to try to decide whether it’s an actual overtemp or erroneous sensor data. The temp sensor TSB was complied with just a few thousand miles prior to this failure. For now my thinking is to do the following:
– Check sensor supply +5 and ground inputs at the gearbox clutch side connector
– Check sensor resistance at room temperature and compare to chart
– Check sensor resistance behavior during warm up while on the lift
– Drive it and see what symptoms re-occur. I’d like to log sensor resistance data while doing this. Considering using a logging multimeter or using a PIWIS to display and log temperature.
Hoping this will give me a good idea of whether the sensor behavior is normal or not. More to follow but progress will likely be sporadic as I have a couple of other projects that will have to take priority.
Took the first small steps in the troubleshooting process this evening.
– Check sensor supply +5 and ground inputs at the gearbox clutch side connector
Disconnected the cable at the transmission and measured a solid 5V sensor supply voltage on the connector (pins 13 and 14)
– Check sensor resistance at room temperature and compare to chart
Since it’s really hard to access the connector on the transmission with it still on the car I instead accessed the connector at the controller end. Measured a steady 0.9 kOhm (pins 3 and 13) which translates to 10 deg C (pretty close to the temperature in my garage at the time).
I also, took a quick look at the cooling valve on top of the transmission. Nothing obvious wrong but will have to take a closer look later if the following steps indicate an actual overtemp condition.
Next planned steps:
– Check sensor resistance behavior during warm up while on the lift
– Drive it and see what symptoms re-occur. I’d like to log sensor resistance data while doing this. Considering using a logging multimeter or using a PIWIS to display and log temperature.
Update!
Cleaned the connector and the area around it carefully. Used electronics cleaner on the pins and seated and unseated the connector a couple of times.
Update!
I was able to get the PIWIS hooked up today. Did a drive long enough to get everything up to temperature. No misbehavior, fault codes or suspect behavior of the temperature parameter. Starting to think the sensor is OK.
After this evaluation I did a PDK calibration for good measure then took it on another fairly long drive. Not a hiccup, ran great. Guess I’ll keep driving it until I get a chance to put it on the lift and drop the pan.
Update!
Nice Spyder. The code (P1731) indicates an shift rod error: “Distance sensor information/shift rod faults (outside of validity range)”
I’m in no way a PDK expert but my take on it is that the sensors indicate a shift rod is not getting to the expected position. I see three possible reasons for that:
1, Problem with the actuation (hydraulics)
2, Mechanical failure on the gearbox side
3, Sensor / wiring issue
My suggested trouble shooting steps for each possibility are listed below. Note that there is very little information available so it will likely to difficult to come up with a definite diagnosis. A shotgun approach may required which unfortunately is expensive and time consuming.
1, Measure pins on clutch side connector.
If you notice anything suspicious consider replacing that solenoid or the whole hydraulic unit. Consider dropping transmission pan and inspect hydraulic block and solenoids for any signs of failure/damage.
2, While you could try to find a transmission shop that is willing to open up the gearbox side it will be very difficult to find any spare parts so you probably want to consider finding a used replacement gearbox or go for the refurbed from Porsche.
3, You can check the connector / wiring on the gearbox side paying particular attention to pins 7-10. I don’t have the expected values for that connector but could probably get them. You can also open the gearbox side and replace the sensors. Per the thread referenced above there are sellers in China that have these.
Wouldn’t hurt to try to run the calibration procedure before doing any of this, you never know (any shop/owner with a PIWIS can do this). Please keep us posted on what you decide to do.
note that your code (P1731) does not indicate an issue with the temperature sensor.
While in no way a sure fix it can’t hurt to clean both connectors on the gearbox.