mk2marty
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- VFii Calais-V
Just thought I'd throw this up here to help out other people with a similar issue, because I couldn't find anything on JC when I looked.
Bought an ex-taxi VFii Calais-V 3.6 a little while ago, that was cheap because it had transmission issues. It took about 3 seconds to engage drive after shifting to D, and when it did, it engaged with a bang. It also had a rough and abrupt shift between 1st and 2nd, and sometimes a flare between 3rd and 4th.
Here it is, doing its best not to look like a Corporate Cab:
Looked at the trans fluid condition, and it seemed OK. Service history for the car said it had been changed at the 150km mark, as per Holden schedule. It had around 290km on it, so was due another filter and serving of ATF. The fluid was old, but didn't look burnt or overly discoloured. Suspected something mechanically wrong - a leaking clutch piston maybe, which would explain the slow drive takeup and harsh shifts, as the ECM commands a gear and ramps up commanded pressure until it finds it (with a bang). Given the mileage it had done, it also wouldn't have been surprising for it to have simply worn out a clutch pack. The fluid condition didn't suggest this though.
Because it had spent most of its life so far shuttling politicians to and from the airport in rush hour traffic, the ex-Holden tech at work suggested that it was worth resetting the learned shift values in the trans to see if it made any difference, as a first step. Took it to the local Holden dealer, who charged an hour's labour to reset it (I should really invest in a scan tool), but surprisingly, it came right for about a day until it relearned all the bad habits again. One bonus was that the dealer pulled some fault codes out of it, all of which related to the TEHCM. They then tried to sell me a new valve body for an astronomical sum, lol. The codes were the following:
P0872 - Transmission Fluid Pressure Switch 3 Circuit Low Voltage
P0877 - Transmission Fluid Pressure Switch 4 Circuit Low Voltage
P0989 - Transmission Fluid Pressure Switch 5 Circuit Low Voltage
Now, I'm just a simple diesel mechanic, but even I could see a theme here. After a little Googling, it looked like plenty of Americans with E90 BMWs had the same issues, BMW having bought a load of 6L45s off GM for their US market vehicles (something something local content, I'm guessing). All of their issues related to the diaphragms in the pressure switches splitting, causing the switch not to react to changes in the fluid pressure acting against its diaphragm. Makes sense - ECM commands a solenoid on, and expects to see a change at the corresponding pressure switch. If the fluid pressure has nothing to act against, the switch doesn't change state. ECM is confused, reverts to default value.
Sonnax in the US do a repair kit for the pressure switches, consisting of new plastic diaphragms (or laminate discs) and seals. They also sell the special tools needed to fit them. They won't, however, sell them to you directly, you need to go through their local agent. So, a little more internet sleuthing needed (because the local agent's markup was more than four times the value of the seal kit). Turns out you can get the seal kits through rockauto.com (just find anything that uses a 6L45/6L80 - I chose a WN Caprice patrol car), and Aliexpress sell the special tools (which are probably copies, but much cheaper, so meh - I'm poor).
So, for anyone who needs it - seal kit here, and special tools here. For a total of $40 NZ, some fluid and a filter (which it was due for anyway) it was worth a shot.
Dropped the fluid and pan, removed the wiring loom plug, modified an external torx head socket to get the valve body retaining screws undone (they look like an external torx, but they're not), and dropped the valve body out on the bench. Separated the solenoid pack from it, and lo and behold - split pressure switch diaphragms!
This is what they're meant to look like (from the Sonnax instruction booklet):
Removed the remnants of the old diaphragms carefully with a pick and used the right angle tool to squeeze the new ones into place. The seal installer tool works really well too, I just made sure to lubricate the seal liberally before plunging it home. Here are the remains of the old seals and diaphragms (and a switch plunger):
Reassembled, refitted, new filter and Penrite LV fluid, and it's happy. It took a couple of hundred KM to re-learn its shift patterns again, but roughly 10000km later it's still fine. I'm calling it a win.
Bought an ex-taxi VFii Calais-V 3.6 a little while ago, that was cheap because it had transmission issues. It took about 3 seconds to engage drive after shifting to D, and when it did, it engaged with a bang. It also had a rough and abrupt shift between 1st and 2nd, and sometimes a flare between 3rd and 4th.
Here it is, doing its best not to look like a Corporate Cab:
Looked at the trans fluid condition, and it seemed OK. Service history for the car said it had been changed at the 150km mark, as per Holden schedule. It had around 290km on it, so was due another filter and serving of ATF. The fluid was old, but didn't look burnt or overly discoloured. Suspected something mechanically wrong - a leaking clutch piston maybe, which would explain the slow drive takeup and harsh shifts, as the ECM commands a gear and ramps up commanded pressure until it finds it (with a bang). Given the mileage it had done, it also wouldn't have been surprising for it to have simply worn out a clutch pack. The fluid condition didn't suggest this though.
Because it had spent most of its life so far shuttling politicians to and from the airport in rush hour traffic, the ex-Holden tech at work suggested that it was worth resetting the learned shift values in the trans to see if it made any difference, as a first step. Took it to the local Holden dealer, who charged an hour's labour to reset it (I should really invest in a scan tool), but surprisingly, it came right for about a day until it relearned all the bad habits again. One bonus was that the dealer pulled some fault codes out of it, all of which related to the TEHCM. They then tried to sell me a new valve body for an astronomical sum, lol. The codes were the following:
P0872 - Transmission Fluid Pressure Switch 3 Circuit Low Voltage
P0877 - Transmission Fluid Pressure Switch 4 Circuit Low Voltage
P0989 - Transmission Fluid Pressure Switch 5 Circuit Low Voltage
Now, I'm just a simple diesel mechanic, but even I could see a theme here. After a little Googling, it looked like plenty of Americans with E90 BMWs had the same issues, BMW having bought a load of 6L45s off GM for their US market vehicles (something something local content, I'm guessing). All of their issues related to the diaphragms in the pressure switches splitting, causing the switch not to react to changes in the fluid pressure acting against its diaphragm. Makes sense - ECM commands a solenoid on, and expects to see a change at the corresponding pressure switch. If the fluid pressure has nothing to act against, the switch doesn't change state. ECM is confused, reverts to default value.
Sonnax in the US do a repair kit for the pressure switches, consisting of new plastic diaphragms (or laminate discs) and seals. They also sell the special tools needed to fit them. They won't, however, sell them to you directly, you need to go through their local agent. So, a little more internet sleuthing needed (because the local agent's markup was more than four times the value of the seal kit). Turns out you can get the seal kits through rockauto.com (just find anything that uses a 6L45/6L80 - I chose a WN Caprice patrol car), and Aliexpress sell the special tools (which are probably copies, but much cheaper, so meh - I'm poor).
So, for anyone who needs it - seal kit here, and special tools here. For a total of $40 NZ, some fluid and a filter (which it was due for anyway) it was worth a shot.
Dropped the fluid and pan, removed the wiring loom plug, modified an external torx head socket to get the valve body retaining screws undone (they look like an external torx, but they're not), and dropped the valve body out on the bench. Separated the solenoid pack from it, and lo and behold - split pressure switch diaphragms!
This is what they're meant to look like (from the Sonnax instruction booklet):
Removed the remnants of the old diaphragms carefully with a pick and used the right angle tool to squeeze the new ones into place. The seal installer tool works really well too, I just made sure to lubricate the seal liberally before plunging it home. Here are the remains of the old seals and diaphragms (and a switch plunger):
Reassembled, refitted, new filter and Penrite LV fluid, and it's happy. It took a couple of hundred KM to re-learn its shift patterns again, but roughly 10000km later it's still fine. I'm calling it a win.
