TRANS FAILSAFE PROG
Discussion
Hello All, I've got a '95 E38 740 and have had the dreaded 'TRANS FAILSAFE PROG' message for the last couple of months which up until this week has had no noticable affect on the gear change.
It is now not changing into first after driving for about 15 mins and starts from 2nd or 3rd which obviously is bad for the clutch and means the car is very slow from take-off. As I said the box changes though the gears perfectly well apart from this and for the first fifteen minutes or so starts from first as well.
Any ideas? Has anyone had this message? And how was it fixed, replies gratefully received before I take it to the garage...
It is now not changing into first after driving for about 15 mins and starts from 2nd or 3rd which obviously is bad for the clutch and means the car is very slow from take-off. As I said the box changes though the gears perfectly well apart from this and for the first fifteen minutes or so starts from first as well.
Any ideas? Has anyone had this message? And how was it fixed, replies gratefully received before I take it to the garage...
TheEnd said:
Does it drive normally for a while, then randomly drop into failsafe, (and usually loacked into 3rd gear)
Shutting the engine down and restarting will cure this for a short while, but that is a symptom of the most common failure, which is an output speed sensor breaking down
Thanks for the info, yes it does drive normally then slips into failsafe...Shutting the engine down and restarting will cure this for a short while, but that is a symptom of the most common failure, which is an output speed sensor breaking down
and also shutting the engine down for awhile cures temporaily....have you experienced this? How many outside speed sensors are there? I suppose this would be picked up on BMW diagnostic?
I've had this before on a 320, and it's the most common autobox fault on 'boxes of that era.
The repair was in the region of £150 i think, the part itself is cheap, but you need to get to it, and then new gearbox oil after.
As with all warnings, if the car flashes something up, then it'll be recorded on the gearbox ecu as to what condition went out of range and made it decide to go into failsafe.
It hints at an electrical problem by working normally until the sensor misses a couple of signals. The ecu decides it can't trust it, and goes into limp. On a restart, it'll carry out a quick checklist, usually find the sensor is back working again, and carry on regardless.
I'm not sure how many speed sensors are inside, the engine's crank sensor is one, the gearbox has an input speed sensor of it's own to detect over revs, and there is an output shaft sensor, i guess it uses this to verify what gear it is in.
Finally there is the car's road speed sensor, which helps the autobox decide changing strategy.
The repair was in the region of £150 i think, the part itself is cheap, but you need to get to it, and then new gearbox oil after.
As with all warnings, if the car flashes something up, then it'll be recorded on the gearbox ecu as to what condition went out of range and made it decide to go into failsafe.
It hints at an electrical problem by working normally until the sensor misses a couple of signals. The ecu decides it can't trust it, and goes into limp. On a restart, it'll carry out a quick checklist, usually find the sensor is back working again, and carry on regardless.
I'm not sure how many speed sensors are inside, the engine's crank sensor is one, the gearbox has an input speed sensor of it's own to detect over revs, and there is an output shaft sensor, i guess it uses this to verify what gear it is in.
Finally there is the car's road speed sensor, which helps the autobox decide changing strategy.
simon768622 said:
Excellent info, thanks....would a diagnostic at a BMW independent pick up a faulty speed sensor or would I have to go to a main dealer?
I would think an independent would be fine. You might also find someone local who has a copy of Inpa / EDIABAS and the correct cable (I have one but I think I'm too far away) or possibly try a local recovery contractor, my mate has a SnapOn thing that does most of the key stuff. Oh, and isn't it a torque converter rather than a clutch?
simon768622 said:
miniman said:
Oh, and isn't it a torque converter rather than a clutch?
probably you're right.....performs the same function as a manual clutch though? starting in 3rd can't do it (whatever it's called)any good..In fact, for pootling about town purposes, my Trans Am never selected anything other than third (out of three) unless you manually selected first or second, the big engines have enough torque to cope.
simon768622 said:
so should i take to a transmission specialist?
certainly, they'll be a lot cheaper then BMW, and it's not like ruining an otherwise perfect FBMWSH.The difficult bit is finding an autobox specialist. Driver Transmissions was one that i was recommended to, and they did fix the problem, but there are others out there somewhere.
http://www.drivertransmissions.co.uk/
Now moved it seems, but without using loads of different places, i can't exactly rank them against others.
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