Volvo XC90 Diesel 2007 - TF80SC - Lock up solenoid stuck in Off Topic is solved

[ramilio]

Hi All,

I've been scouring the forums but haven't found anything specific to my problem.

I have a 2007 XC90 Diesel with the TF80SC which is throwing a TCM0051 error: "Lock-up solenoid SLU stuck in position OFF". The issue seems to be triggered under load e.g. driving up a hill. The transmission is occasionally flaring and hard shifting also. "Transmission Service Required" is displayed.

I have changed the trans fluid three times using drain/flush. Have also reset the fluid counter. It has made no difference, still getting the same error. Car has never been used for towing.

I have read that TF80SC's of this era have a weak valve body - Is this likely related or something different? Didn't want to pull the trigger on a recon valve body until I could be fairly certain it was the issue.

Any help or pointers would be much appreciated. Keen to get back on the road again!

Thanks
Ramilio

[ggleavitt]

Some reference to shift issues with pre-06J AW serial number TF-80SC transmissions here- https://www.swedespeed.com/threads/2006 ... fo.304297/

[ramilio]

Thanks Ggleavitt, reading through the posts. Very similar issues but the lock up solenoid issue seems to go unmentioned.

Interestingly by transmission is an 06K

[ggleavitt]

Here's a thread noting 0051- https://www.swedespeed.com/threads/tf-8 ... ds.504417/, see post # 9 for reference. Serial number is 06K, go figure. Maybe the 06J cutoff is really not a hard cutoff.

Error code definition from VIDA- 437: TCM-0051 Lock-up solenoid SLU. Stuck in position OFF, D5244T4, TF-80SC AWD
Condition
The transmission control module (TCM) checks the function of the lock-up solenoid by comparing the speed signal from the transmission speed sensor with the speed (RPM) signal from the transmission speed (RPM) sensor. The signals should "show" the same calculated speed. The transmission control module (TCM) also compares the speed from the transmission speed sensor with the engine speed (RPM). RPM should be greater than or less than transmission speed depending on which gear is engaged. If Transmission control module (TCM) detects that speed and RPM signal do not match the calculated values, this means that lock-up is slipping or not engaged and the diagnostic trouble code is generated. The diagnostic trouble code (DTC) can be diagnosed when driving normally.

Substitute value
Adaptation function is blocked.
Lock-up function is blocked.
Slip lock-up function is blocked.

Possible source
Contact resistance in the terminals
Open circuit in lead for control signal or signal ground.
Solenoid not working.
Solenoid stuck in closed position.
Internal fault in transmission control module (TCM).

Fault symptoms
General warning lamp lit
Malfunction indicator lamp (MIL) lit.
Harsh gear changing
No gear changing.
Abnormally slipping gears.

edit- fix last paragraph strike-throughs