'Gear Selector Service Required' and TCM-DD01 Topic is solved

Post by **Kara503** » 12 Sep 2019, 21:07

2006 S60R, auto transmission.
No OBDII codes stored, info display reads 'Gear Selector Service Required'.

Tried a new GSM (Gear selector module, the circuit board that lives under the shift knob)- no change.
The lights on the shifter are never lit. the car shifts normally but with no geartronic function.
The car behaves the same whether I plug the GSM in or leave it unplugged, and this the same with the original module.

ViDA gives me the code TCM-DD01 and fault tracing tells me to check the signal inputs with a special Volvo tool I don't have, then tells me to replace the GSM.

Any thoughts on how I should proceed? Should I just assume the original module plus the one I got from the scrap yard are bad?

Post by **RickHaleParker** » 12 Sep 2019, 22:06

TCM-DD01 The communication lead between the gear selector module (GSM) and the transmission control module (TCM) is short-circuited to voltage or ground.

Check the wiring between the GSM and the TCM.

Post by **Kara503** » 24 Sep 2019, 17:38

Found that same bit of info in my copy of VIDA after a bit more looking. It really is an amazing program!
I'm a bit embarrassed but I need some more help. I'm not sure if I am checking it correctly.

4 wires leading to the GSM, I checked all of these on the GSM control board itself and identified each cable using the wiring diagram from VIDA.
Black = Ground. I checked for continuity to another ground (Cigarette lighter) and found it to have 0 ohms/ normal continuity.
Green/White= Communication from TCM. Found to be getting battery voltage (13V) and has continuity to ground.
Blue/White= Power from CEM. Found to have 9mV, has continuity to ground.
Violet/ White= Also listed as power from CEM , getting 90 mV, no continuity to ground.

Do I interpret my result for the communication cable as that cable being shorted to ground? Or am I doing it incorrect?
If that does mean its shorted, do I just have to follow the cable all the way from the GSM to the TCM and see if it is bare and contacting metal somewhere? Also, after the car has been running for about 30 seconds I get the 'Gear selector service required' message whether I leave the GSM plugged in or not. Not sure if that helps.

Thanks for any help, hope this makes sense

Post by **abscate** » 25 Sep 2019, 03:34

Post up a picture of the GSM wiring and we will crunch through it.

Post by **RickHaleParker** » 25 Sep 2019, 04:16

Kara503 wrote: ↑24 Sep 2019, 17:38 4 wires leading to the GSM, I checked all of these on the GSM control board itself and identified each cable using the wiring diagram from VIDA.
Black = Ground. I checked for continuity to another ground (Cigarette lighter) and found it to have 0 ohms/ normal continuity.
Green/White= Communication from TCM. Found to be getting battery voltage (13V) and has continuity to ground.
Blue/White= Power from CEM. Found to have 9mV, has continuity to ground.
Violet/ White= Also listed as power from CEM , getting 90 mV, no continuity to ground.

Black: Ground sounds right.

Green/White is a CAN Bus. It should not have continuity to ground. Check for shorts between the Green/White and the Black.

Blue/White is a ground from the CEM, it should have continuity to ground.

Violet/ White is the power from the CEM, see the fuse F21 on that line, it should not have continuity to ground. It should have more then 90 mV. Check fuse F21 and check for shorts between Violet/White & Blue/White.

3/156 Gear Selector Module (GSM), 3/155 Mode selector, 8/36 Shift lock solenoid.

Post by **Kara503** » 25 Sep 2019, 15:53

Fuse F21 was blown and replacing it fixed the problem. I guess we will see if it blows again.

Not only did I have no idea the CEM has a fuse panel but nowhere in VIDA did it tell me to check that fuse or even mention its existence. I saw 'F21' in the wiring diagram but assumed it was a relay or something.

Thanks a million for your help Rick, I really appreciate it.

Post by **RickHaleParker** » 25 Sep 2019, 17:13

Kara503 wrote: ↑25 Sep 2019, 15:53 'F21' in the wiring diagram but assumed it was a relay or something.

If it starts with an F, it is a fuse. The rectangle with a line through is a symbol for Fuse .
Relays are marked 2/XXX and will show switches and coils.

viriia · Post by **viriia** » 26 Oct 2019, 03:27

2009 xc90 3.2
The message has popped up GEAR SELECTOR SERVICE REQUIRED' AND TCM-DD01.
I have checked the fuse F21 and it is alright. Any other ideas how to fix it?
thanks

Post by **RickHaleParker** » 26 Oct 2019, 19:11

viriia wrote: ↑26 Oct 2019, 03:27 I have checked the fuse F21 and it is alright. Any other ideas how to fix it?

There are some listed that way ↑ .

viriia · Post by **viriia** » 26 Oct 2019, 22:57

i have found the ribbon cable was broken. do u have any ideas how to replace that cable ?