Transmission Malfunction Service Now - Stop Start not working

[ACS79]

Hi All. 

I have a 65 plate 1.5 focus with automatic transmission. Recently the stop-start has stopped working completely. Prior to it not working, when it kicked in, it felt like it was throwing the car forward when the engine restarted. I now have an error on the dash stating "transmission malfunction" the stop start is the only issue. The car is running fine and the gear changes seem normal when driving. Any ideas?

Thanks 

[DaveT70]

Need more info on what transmission is fitted.

Is it Petrol or Diesel?

6F35 auto or Powershift?

When was the battery last changed?

[ACS79]

Thanks for getting back to me. 

It's powershift and petrol. 

battery was changed recently after the problem thinking that would fix it. It didn't. Still same error and stop start not working 

Thanks 

[ACS79]

5 hours ago, DaveT70 said:

Need more info on what transmission is fitted.

Is it Petrol or Diesel?

6F35 auto or Powershift?

When was the battery last changed?

Thanks for getting back to me. 

It's powershift and petrol. 

battery was changed recently after the problem thinking that would fix it. It didn't. Still same error and stop start not working 

Thanks

[DaveT70]

Mmmm 2015 Petrol, are you sure it's a powershift?

Send me your reg number on a PM and I'll check

[DaveT70]

@ACS79

Thanks for providing your reg

It's a conventional torque convertor automatic, 6F35, not a powershift

P2796? Are you sure that's the right code? Nothing is coming up.

When was the battery last changed?

Is the battery condition good, you mention S/S is no longer working, poor battery performance causes issues with the transmission operation.

The PCM and TCM are combined within the PCM on these models (No seperate TCM), your PCM has an update available, I would recommend getting this done as it may include a refined transmission calibration

How many miles has the transmission done?

If it's over 40,000 miles and has not had the fluid changed then I recommend to change the fluid ASAP.

If the fluid is very dark when you take it out, refill, run for 500 miles, change again

 

[ACS79]

12 hours ago, DaveT70 said:

@ACS79

Thanks for providing your reg

It's a conventional torque convertor automatic, 6F35, not a powershift

P2796? Are you sure that's the right code? Nothing is coming up.

When was the battery last changed?

Is the battery condition good, you mention S/S is no longer working, poor battery performance causes issues with the transmission operation.

The PCM and TCM are combined within the PCM on these models (No seperate TCM), your PCM has an update available, I would recommend getting this done as it may include a refined transmission calibration

How many miles has the transmission done?

If it's over 40,000 miles and has not had the fluid changed then I recommend to change the fluid ASAP.

If the fluid is very dark when you take it out, refill, run for 500 miles, change again

 

Thanks for your reply. Yes that is the code. I have attached the photo.

The battery is brand new as I thought that was causing the issue so purchased a new one 

The car has only just done 30000 miles 

[DaveT70]

8 hours ago, ACS79 said:

Thanks for your reply. Yes that is the code. I have attached the photo.

The battery is brand new as I thought that was causing the issue so purchased a new one 

The car has only just done 30000 miles 

Suspect the auxiliary fluid pump, the one that keeps the system pressurised while the engine is off in stop/start mode (did you not say S/S isn't working?)

Check electrical connections first

Check all fuses

Remove the air cleaner assembly completely and underneath, on the chassis rail, you will find two or three earth straps.

Remove the straps, clean the paint away from the area where the earth eyelet sits, grease and re-fit

Do this also on the main earth strap from the battery to the body, above the fuse box

Using FORscan, reset the BMS as you have fitted a new battery and do a master reset of the PCM

If the DTC comes back, then it's looking like the aux pump has failed, it's on the outside of the transmission though, so not too much of a big job.

Get your fluid changed anyway, Mercon LV isn't that good, I have switched to DEXRON 6 I get much smoother changes now

 

[ACS79]

5 hours ago, DaveT70 said:

Suspect the auxiliary fluid pump, the one that keeps the system pressurised while the engine is off in stop/start mode (did you not say S/S isn't working?)

Check electrical connections first

Check all fuses

Remove the air cleaner assembly completely and underneath, on the chassis rail, you will find two or three earth straps.

Remove the straps, clean the paint away from the area where the earth eyelet sits, grease and re-fit

Do this also on the main earth strap from the battery to the body, above the fuse box

Using FORscan, reset the BMS as you have fitted a new battery and do a master reset of the PCM

If the DTC comes back, then it's looking like the aux pump has failed, it's on the outside of the transmission though, so not too much of a big job.

Get your fluid changed anyway, Mercon LV isn't that good, I have switched to DEXRON 6 I get much smoother changes now

 

Thanks again

Yes, I have ran all of the resets and checked all fuses and the DTC comes straight back on.

I'm confident I can fit a new pump but I am unable to locate one. Can't find them anywhere online? Any ideas?

 

Thanks. 

[DaveT70]

On 7/15/2022 at 1:53 PM, ACS79 said:

Thanks again

Yes, I have ran all of the resets and checked all fuses and the DTC comes straight back on.

I'm confident I can fit a new pump but I am unable to locate one. Can't find them anywhere online? Any ideas?

 

Thanks. 

Probably Ford only