XC90 - 2008 - V8 - could this be a gear position sensor issue?

jodisxc90 · Post by **jodisxc90** » 27 Aug 2019, 18:01

Problem started a few days ago. Upon start-up, shifting into Drive, the car automatically goes into MANUAL mode. No, the shifter itself does not...by the display on the dashboard shows numbers, the indicator near the shifter lights up M. The shifter stays in the proper Drive position. I can drive the car and use the manual shift function (once i bump it over to the proper position). After a few miles on the road at speed, the indicators randomly start showing D...on both the dash and the shift indicator. No noticeable changes, RPM shift, etc. I can shift back to normal Drive mode and continue to drive with mo additional issue. Once you stop and turn the car off...it will happen all over again.

I have taken the checked for loose connections on the indicator panel and all seem to be in order. Pulled the indicator panel and the shifter stop...nothing seems out of the order. Additional, when I have the indicator panel loose, I can still move the shifter and the gear indicator moves, just as if it were sitting in the proper spot...straight into Manual instead of Drive.

All I can figure is the gear position sensor under the hood. Any thoughts...???

Post by **jimmy57** » 27 Aug 2019, 20:24

No, the gear position sensor is an integral part of the TCM that mounts on top of trans around the gear lever shaft. The manual shift function is the control of the GSM, gear selector module. That is the top cover of the gear lever assembly/shifter inside car. There is a magnet on the gear shift shaft and a circuit board with 3 sensors to know where the magnet is. If the magnet is sensed to be in the manual gate then the indication on cluster changes. There is a forward sensor for forward lever motion and a rear one for lever sensing in that direction.

jodisxc90 · Post by **jodisxc90** » 28 Aug 2019, 06:48

Yeah...that is exactly what I thought it was, but since the gear position changed even with the top cover removed, I thought the sensor part may be in the forward engine compartment. SOOOO... since the problem seems to be in the cover (and yeah, I did know where the sensor is - located in the top portion of the shifter "stop" assembly)...I also saw the magnet attached to the shifter. Is it possible the magnet is out of alignment? Should I go ahead and replace the GSM? What would you do you think my course of action should be? Thanks a million for your help...

Post by **jimmy57** » 28 Aug 2019, 16:09

The gear position as far as PRNDL.. is the gear pos sensor in TCM. If you numerical gear position that is gear tronic feature based on GSM indication to TCM. In some part of that cars life something could have been spilled into leaver opening and the GSM may be doing crazy stuff.

jodisxc90 · Post by **jodisxc90** » 28 Aug 2019, 16:14

I guess anything is possible there Jimmy. Is there a way to clean/test the GSM or is the best mode to just replace that sucker. Thanks again bud

jodisxc90 · Post by **jodisxc90** » 28 Aug 2019, 18:51

Just pulled the gear shift console parts again. Popped the GSM sensor panel (small circuit board on the bottom of the shift stop section). Inspected it really well and I think that I see exposed (possible broken) wiring in the ribbon connector that runs from the sensor to the main gear selector main unit...hope that is the answer. Is there a place I can purchase just that three position circuit board? it would be a super easy fix.

jodisxc90 · Post by **jodisxc90** » 02 Sep 2019, 08:11

Good news...got it fixed. Long story and lots of trial and error. Went to a u-pull-it junk yard, found a 2008 xc90, puller the whole GSM and swapped them out...a bit of wire cutting and reconnecting...but no big deal. Trans now shift properly. Cost me $9.00 instead of $220 from Volvo..