Need expertise advise: Trans. Pressure Actuator2 (P0700, P0778)

[BMW2007]

sifu, help needed... lately my 525i has an error of trans. failsafe prog after not using for weeks. It seems like the transmission went into safe mode whenever the switch is ON. The car still can move but kind of stuck at 4th gear or so. Drove the car moving around for a while then turn OFF the engine, the trans. failsafe prog message was cleared by itselft after restart (note: car must move for a while before restart).However, the same error messgae will pop up again on the next day when the car is start up. Drove the car moving around and restart, error on the OBD meter will be cleared by itself. This process/scenario repeated for few days already. Sent the car to the mechanic for reading out the error code in the eveving, the error code found as Pressure Actuator 2 (P0700, P0778). Didn't have time to further troubleshoot the faulty part as it needs more time. The mechanic said it might be Solenoid valve but not too sure which valve is having problem. Help needed: 1. Is the Presurre Actuator = Solenoid valve? i dont think so, right?2. How to confirm if the fault part is Pressure Actuator or not? 3. How many Pressure Actuator inside the GB? Which one is Pressure Actuator 2?thanks so much!

 

[moots]

the fact that you mentioned you left the car for weeks leads me to suspect the battery.the AGS is very sensitive to battery condition.have it tested on load and recharge if required.do the easy and cheap stuff first,,,,,gud luck

 

[BMW2007]

i did the battery check, it shows ~12.4V with engine off, it shows ~13.5V with engine and air-con/headlight On, then ~14.1V when air-con/headlight off. I think the baterry/alternator is working fine.

noticed one more thing, the OBD shows error messages "Check Break Light" and "Check Rear Foglight" occasionally when the OBC shows Trans. Failsafe prog. However, there is no problem to the break light or rear foglight. Dont understand why OBC triggers check lights message?! Any posibility of electrical connectivity or contact related issue?

 

[haywire]

I had similar symtoms last year when my alternator was on its way out. Its not dead yet, but getting there on its last legs and sometimes doesnt charge the battery. Sometimes ok, sometimes dont. When the roadside assistance came to diagnose the car, it was charging fine, but sure enough two days later the alternator died on me and I'm stranded on the side of the road, just over the border to Scotland.

 

[BMW2007]

hmm... this is strange. not sure whether my alternator still in good condition or not, but i still can start the engine without any sign of battery weak. Fyi, i only start the engine to warm it up for about 15~20 mins every 2 or 3 days without driving the car. The battery seems to be no problem for me to start the engine.. how to check the alternator?

Anyone knows how many Pressure Actuators inside the GB and Which one is Pressure Actuator 2?

Thanks.

 

[tweiboon]

hmm... this is strange. not sure whether my alternator still in good condition or not, but i still can start the engine without any sign of battery weak. Fyi, i only start the engine to warm it up for about 15~20 mins every 2 or 3 days without driving the car. The battery seems to be no problem for me to start the engine.. how to check the alternator?

Anyone knows how many Pressure Actuators inside the GB and Which one is Pressure Actuator 2?

Thanks.

eeehhh................. last time i got same problem while i am having e36. My problem that moment is the gearbox dirty. Change the filter and flush the gearbox then ok already.

 

[BMW2007]

bro tweiboon, did u get the same error code or "pressure actuator 2" in your case?

 

[BMW2007]

i guess the pressure actuator is labeled as #2 as below, however there are 3 units linked to #2. Anyone know which one is Pressure Actuator 2 or Pressure Regulator Solenoid B in some others OBDII tools (center, left or right one)?

 

[bimmer73]

There are 6 Selenoid valve in the GB if not mistaken. you can also try removing you ECUs and then plug them in again

 

[BMW2007]

i got the ATF, filter and battery changed yesterday, the trans failsafe message was gone for the 1st hour. Believe that with the new battery has solved the issue for a while. However the error message trans failsafe came back after 1~2 hours later. Did the OBC test 9 last night, it shows 12.2V when switch is in ON position. Start the engine, it shows 13.8V without load. It was then dropped to 13.4V with aircon, headlight (HID), Door lights, Foglight ON. The trans failsafe message still there. Is the voltage reading above show normal? Thanks