Meekoblue Posted March 8 Share Posted March 8 (edited) Hello Ive recently been having Transmission Limited Function errors on the dash and some rough gear changing, sometimes in limp-home mode and needed to be towed. Forscan only once found an error - P0766. Not sure of service history so changed filter and oil and was much better -for nearly 100miles then only even number gears available (no R, 1, 3, 5). Power off-on and cleared and working again since. Module self-test fine but cant do clutch relearning as transmission oil temp remains too low! Used oscilloscope function on the solenoids in TCM and initially some very erratic "Actual" readings. So Im wondering if a real hard mechanical fault with solenoids, or maybe a wiring/module/earthing fault? However!... Managed to get it to repeat a few times. Always in the highway. Errors show solenoid C and D. Sometimes gears 1,3,5 working, other times 2,4,6. Not really convinced its the solenoids but possibly wiring/earth voltage spikes. I've tried monitoring OBD voltage during driving using Torque and its showing voltage spikes/dips! Then again... Went for a drive today and error 4 times "transmission limited function" twice with a yellow warning but twice with a red warning symbol. Odd! Each time cleared with power off/on. Each time during up-hill acceleration (not harsh but climbing) Journey was 70 miles. Return was error free. Came home. FORScan found NO TCM errors! I'm scratching my head now! Only thing I can imagine is fluid level low, car climbs, fluid drains from front of gearbox starving solenoids.... ? Any and all ideas much appreciated! And just to add: today running great with no problems. About 30 miles mixed driving. Edited March 8 by Meekoblue Additional info Quote Link to comment Share on other sites More sharing options...
LostNTransit Posted March 8 Share Posted March 8 If one puts their trust in third party software, then one will get third party errors. I'd never put my trust in forscan. 2 Quote Link to comment Share on other sites More sharing options...
Meekoblue Posted March 9 Author Share Posted March 9 Fair point but I don't have access to alternatives at this time. Quote Link to comment Share on other sites More sharing options...
alanfp Posted March 9 Share Posted March 9 1 hour ago, Meekoblue said: Only thing I can imagine is fluid level low, car climbs, fluid drains from front of gearbox starving solenoids Quite possible. I would check fluid level and top up if required. When you changed the oil, did you do it exactly as Ford recommends? Quote Link to comment Share on other sites More sharing options...
DaveT70 Posted March 9 Share Posted March 9 7 hours ago, LostNTransit said: If one puts their trust in third party software, then one will get third party errors. I'd never put my trust in forscan. ForScan gives dealer level and higher diagnostics, if you know what you're doing. Why not trust it. Quote Link to comment Share on other sites More sharing options...
DaveT70 Posted March 9 Share Posted March 9 Hi, Sounds like comms issues. But first: Make sure the battery is in tip top condition, Powershifts do not like poor batteries. Check ALL the earthing points are clean and making good contact, the main earth from the battery to the body and all the engine/transmission earths in the engine bay. Remove the straps, clean the paint away from the body, grease and refit. Once you have reconnected perform a master reset of the TCM using FORSCAN Also, reset the transmission as in video Then you need to start looking for breaks in the comms wires, very common fault. On an S-Max/Galaxy the culprit is the main, large block connector in the LH front wheel arch. Check for broken/damaged wires there, if you don't find any then you need to check the continuity for every wire from the transmission to the TCM and PCM until you find the fault. Overlay a new wire or repair the section. Only after you have confirmed all of this should you start pulling the transmission apart Have a read of this too, paying particular attention to the warnings. I'm sticking with it's comms issues, broken wires https://www.yourmechanic.com/article/p0766-obd-ii-trouble-code-shift-solenoid-d-performance-or-stuck-off-by-yourmechanic#:~:text=P0766 is a diagnostic trouble,be triggered in your situation. Quote Link to comment Share on other sites More sharing options...
Meekoblue Posted March 9 Author Share Posted March 9 Thank you SO MUCH! I'll take all that on board. I'm suspecting the battery as I keep getting low battery error messages after turning the engine off. It seems to provide 14v but falls to 12v when engine stopped. I suspect it can't support load surges. Just going to buy a decent 80aH today. Quote Link to comment Share on other sites More sharing options...
DaveT70 Posted March 9 Share Posted March 9 Definitely start with the new battery then, whilst the battery is disconnected clean the earth points, reconnect the battery and reset the transmission. The fault may go away Quote Link to comment Share on other sites More sharing options...
Meekoblue Posted March 10 Author Share Posted March 10 battery changed. Found the positive terminal clamp was loose! Doesn't help any... Disconnected the transmission plug and found it had somewhat corroded terminals so cleaned with contact cleaner and reconnected. Reset TCM and done 30-odd miles running nice. 2 Quote Link to comment Share on other sites More sharing options...
DaveT70 Posted March 13 Share Posted March 13 On 3/10/2023 at 6:47 PM, Meekoblue said: Battery changed. Found the positive terminal clamp was loose! Doesn't help any... Disconnected the transmission plug and found it had somewhat corroded terminals so cleaned with contact cleaner and reconnected. Reset TCM and done 30-odd miles running nice. Hopefully, it's sorted then. Quote Link to comment Share on other sites More sharing options...
Meekoblue Posted March 14 Author Share Posted March 14 I can happily report that I did a long journey last night and returned successfully. Car running & feeling great. Thanks for the advice! 2 1 Quote Link to comment Share on other sites More sharing options...
DaveT70 Posted March 14 Share Posted March 14 54 minutes ago, Meekoblue said: I can happily report that I did a long journey last night and returned successfully. Car running & feeling great. Thanks for the advice! Brilliant and that's all Alison had to do, last year 2 1 Quote Link to comment Share on other sites More sharing options...
Meekoblue Posted March 14 Author Share Posted March 14 I did have a scary moment earlier though. "Bing!" And a message on the dash! But it was just the routine engine service reminder! Ha! 1 1 Quote Link to comment Share on other sites More sharing options...
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