AWD Transmission: XC 90 wont reverse up hill

[Jonesy767]

Newbie to XC 90

I recently bought an XC 90 R Line privately 51000 miles 2010 model , the car required a full service which I was happy with service included cam belt water pump all oils and filters etc by a trusted local garage .

The problem which my garage has never experienced and it would seem the local Volvo agent had no knowledge .

The car drives perfectly goes through all the auto gears forward and reverse but if parked on an incline and reverse engaged the engine will not rev to gain traction to reverse ????? on the level no problem it will go forward from standstill but not reverse.

Parking brake not an issue

The tilt sensor has been recalibrated but wasn't an issue , the transmission fluid is good level but needs changing (next week)

Any ideas would be gratefully received

[Tannaton]

Try disabling DSTC (traction control) and see what happens?

That's a random suggestion by the way, but with some substance that DSTC is one of the few systems that can override commanded throttle.

[Jonesy767]

Tannaton , thank you that worked, well done Volvo main agent wasn't aware of that thank you

[gmonag]

Not bad for a random suggestion!

[paddy74]

Great suggestion @Tannaton!

But to what fault does this point? Just out of curiosity as I have no idea...

[Tannaton]

. !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
. !!! BACK OF THE NET !!! !!!
. !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

However, that doesn't fix the problem, it just alleviates the symptoms...

Next I would check the ABS tooth rings on the front CV joints for cracks, the splines on the front driveshafts/hubs, the tightness of the front driveshaft retaining bolts and all the wheelbearings.

If that yields nothing then the next step is to get VIDA to read the wheel speed on all four corners and see if one is out of sync? You could also try with a lot of steering lock applied, in both directions, if that changes the behavior then your problem is at the front of the car.

My thinking is that either the front driveshaft splines are damaged and one of them is slipping in reverse, as the ABS ring is on the CV joint not the hub this will make the ABS system think that wheel is losing traction and hence override the throttle.... OR one of the wheel sensors/rings has an issue and is causing incorrect readings, sometimes this can be a failing wheel bearing with play which causes the gap between the sensor and the ring to vary. FYI on the rear the tone rings are part of the bearing, not the CV joint.

The positive side of this is the problem is not your gearbox, if you can pinpoint it then it's likely something much cheaper...

I feel like I've earned a pint now.... except I gave that up for lent!

[Jonesy767]

Tannaton ,

Thank you once again , that was my biggest fear transmission failure . Many thanks for the added info, I will chase up your suggestions with my spannerman .
Just for info the XC was a Chelsea tractor spent 9/10 of its life in London hence low mileage and in all likelyhood spent its life doing under 10 miles an hour !!

[IainG]

Hi
Just makes me wonder where all the experience of actual faultfinding and knowledge at the dealers has gone?

. the local Volvo agent had no knowledge .

.

What a simple test to at least isolate the error to one system.

Iain

[Jonesy767]

Just for info , I took the car to my local independent garage, the owner was baffled as despite the problem no fault codes appeared on his readers of which he used 3 different brands he also contacted a colleague at a Volvo main dealer and borrowed their reader to no effect but he did explain the problem and all concerned had not seen this before .

With the advent of electrickery in vehicles today it reduces alot of mechanics to basic fitters of modules sadly

[TruckbusUK]

Originally Posted by Jonesy767

With the advent of electrickery in vehicles today it reduces alot of mechanics to basic fitters of modules sadly

Mmmm, your XC90 is a 17 year-old design ..... none of these guys should be that far behind if they do this for a living ... and the "dealers" excuse .... I'd be having a word with the workshop master tech and the service manager.