XC90 Stuck in park.
 

Hi All,

I'm new to this forum and realise that this topic has been posted a few times, but after looking through many of the threads I am not sure I can find a solution, so grateful of any help/direction.

I have a 2007 XC90 3.2 Petrol Auto.

The issue I have is that my interlock solenoid is not clicking out when I put my foot on the brake.

I can hear the solenoid click in when I switch the ignition on and I can hear it click out again about 10 seconds after I turn the ignition off, but it will not do anything when I touch the brake.

My brake lights come on fine, so the brake switch is working ok.

Before it stopped working completely, a few times when I put my foot on the brake I would hear the solenoid clicking in and out multiple times rapidly, but would then work ok... now it has stopped completely with the brake.

I opened up the console and pushed the solenoid in and out, it moves freely, I watched it click out and return when the ignition was turned on and off, so looks like the solenoid works ok.

Is there anything else in this circuit other than the break pedal switch? Could it be a computer management thing? I have not been able to test for any messages, nothing comes up on the dash.

The cable from the ignition seems to move the linkages with no issue and I think the button in the gear lever seems to work fine, it feels like it is electrical to me, but unsure.

Great to get any thoughts on what this could be?

Thanks,

DJ

If I recall correctly, the brake pedal has 2 switch circuits.
Check the wiring diagram to confirm.

Hi Swiss,

Thanks for this......... just had a look at the wiring diagram on line and it looks like both the brake lights and solenoid run off one circuit. In both the diagram for the Shift Lock and Brake lights it shows it as component 3/9 (Brake Light Contact) and both feed into C:34 and B:11 on the Central Electronic Module.

It then shows the CEM feeds to the Gear Selector Module, which then runs the solenoid. Could it be that the GSM is not recognising it is in park?

Should I take it into a garage and check if any faults are coming up?

Thanks again,

DJ

Could you check the output to the solenoid from the CEM? Perhaps check all the fuses on the CEM too. I think this is a known failure and is often caused by water ingress into the top of the CEM when the scuttle panel / windscreen wiper area gets clogged up with debris causing a small lake to form. There are specialists who can repair it.

At this stage your best bet is to use VIDA, read the faults, clear them, and test if you can control the solenoid manually in VIDA.

Hi,

Sorry for the delay, finally got back to looking at my Volvo, I don't actually have a VIDA, so just did a bit more digging.

I checked the voltages to the Gear Selector Module:

- Once the ignition was turned on, the 12v powering the solenoid turns on and engages the solenoid.
- When I press the brake on and off a 12v signal switches on and off at the the board, but it does not switch off the solenoid, power stays on.

I opened up the Gear Selector Module unit and found that there was brown stuff all over the circuit board (I've attached a photo). I've tried cleaning, but it made no difference.

Therefore my obvious conclusion is that it must be this board, It will cost me about $300 for a new one here in Australia...... jus thought would double check with you guys I am not missing anything obvious?

Cheers,

Hard to tell from the pock but looks like youve had a capacitor go very bad.

I see a microcontroller and a crystal oscillator. So there's a CPU doing something. Whether it has any vehicle-specific firmware loaded is unclear.

If you do not want to go the easiest way (replacement with new part), then you can try getting a 2nd hand board from a wrecker. Make sure part numbers match!

Or alternatively, try determining where the fault is on the board and repairing it.
May be easy, may not be.
Start with tracing the circuit board traces from the solenoid back through the board.

There's a power IC on a heatsink on the bottom right, that may be switching some current. It might be switching the solenoid....

I don't see any electrolytics in the area most affected, and that area is also widespread. I'd put my money on this being caused by a spilt soft drink, given the proximity of the gear selector assembly to the cup holders. The phosphoric acid content of the well known cola drinks is high.

Hi, I have a spare complete unit. I bought it second hand as the gear knob was leathered and only replaced that on mine. I am about to 'skip' the rest.

Where is thispcb located? Is it under the flap wich supports the gaiter.

Let me know and you can have for the cost of postage.

John l