XC70 intermittent steering controls
 

Hi all! There are a couple of topics on here but nothing quite like what I've got going on, so hopefully someone will be able to enlighten me.

I took my '05 XC 70 through the car wash and it since has developed an intermittent electrical fault. I don't have any evidence the car wash was the cause but it's a big coincidence if not, so I'm suspecting water ingress somewhere.

Key faults are intermittent function from everything on the steering column - left stalk (indicators, headlight), right stalk (wipers) and steering wheel itself (cruise control, radio controls). I don't have a warning light on the dashboard for the airbag so I don't _think_ it's the clock spring that's gone.

So far I've pulled out every relay from the fusebox in the engine compartment (passenger side just in front of the windscreen) and cleaned all the connections with contact cleaner, but that hasn't fixed the problem. I think my next question is - is there anywhere else I should be looking to clean under the bonnet? Presumably there will be looms / connections from the steering column through the engine bay to the headlights / wipers etc, but I don't know enough about the internals at this point to chase down where the fault might be. Anyone have any suggestions where to start?

The place to look is the CEM which is a big L shaped black box above the accelerator pedal , you need to take off the black windscreen panel too where the wipers go through and you will see the top of the CEM in the corner under a plate take the plate off , take out the two multi plugs and look carefully for damp or corrosion on the sockets and the pins down on top of the CEM . You might want to take the CEM out and take it apart to clean any corrosion off the circuit board use a toothbrush and plain water ..

There are two screws on top the CEM you have to remove , and the 3 or 4 plugs on the CEM inside the car . There is a catch on the bottom of the CEM you release and the CEM will fold down and out .

You may be lucky if you take it apart and dry and clean it ..

This is a known problem and there is a modified waterproofing kit for the top which you will need . If you have corrosion in the top plugs ( a big and a smaller one ) you can get these from Volvo ready wired to repair it .

Worst case , the damage is already done and you need a new CEM ..

Thanks Clan, that’s really useful! I’ve found a couple of guides to help take the the CEM out, so that should be something I can get to this weekend.

One quick question - my idea where I can get the modified waterproofing kit from? Is this a Volvo part or is it something aftermarket to address the problem? Thanks!

It is an official volvo modification , they will have a service bulletin listing the parts , but you need to see what you need first if this is indeed the problem . you might need just one of the upper plugs rather than both .

So after much struggling I finally managed to remove the wipers over the weekend and pull the CEM. The waterproofing at the top doesn't actually look in too bad a shape, and the two top plugs were both fine. I opened up the CEM and had a bit of a dig and found two small spots of corrosion - now cleaned up with toothbrush and a load of contact cleaner:

https://i.ibb.co/DDR9kWQ/IMG-0737.jpg

Before I reassamble everything to see if that was the root cause, two more questions:
- am I ok to use antiseice (Coppaslip or similar) when reinstalling the wiper arms?
- is there anything I can apply to the waterproof top cap to improve the seal? It looks like there's a rubber seal round the edge - I reckon a decent application of grease would help no end, but obviously don't want to perish the seal by using the wrong stuff. The two options that spring to mind are either Vaseline (cheap and easy to get hold of) or silicone grease (usually pretty inert but a bit more expensive). Is there a recommended grease for the seal?

Very good ! So water has been getting in , are you sure there are no stains around the pins on the top two plug sockets on the Cem ?

The damage may have already been caused of course , But i hope it works when you put it together .
Don't bodge it , buy the proper waterproofing kit from Volvo it is completely different to the set up you have now and will stop further water getting in .

Yep, definitely no stains from the plugs - the plugs themselves looked completely clean and all the pins were spotless too. I’ll double-check though before I reassemble.

I hear you on the waterproofing kit, will get in touch with my local dealer to get one ordered. Only reason I thought of reusing the current cover is that it looks like the replacement kit (according to a cursory google search) its a fairy flat plastic unit rather than the “tall” model, but probably worth replacing in its entirety given its already leaked once.

Also I’ll have a dig through the cowl drain holes before reassembly, just to make sure they’re clear 👍

It sounds like you already have the later waterproofing kit , no point in changing that .. you might be lucky in that cleaning the corrosion may fix it .

I watch a lot of AvE I think what you could use is "conformal coating"

Had some time to have a dig this weekend...

- Cowl drain holes are clear (but I was a bit surprised how they weren't level with the bottom of the cowl area - there's a good cm or so of lip so the cowl needs to get some water in there before it will start draining!!)
- CEM is still not happy. Managed to get turn signals and steering wheel controls working briefly, but after a minute or two at idle they stopped working again.
- I also appear to have developed a new warning: "Reduced Engine Performance". I can only assume that's due to me cleaning the CEM, and some of the gunk has gotten onto other parts of the board.

At this point I think it's time to hold my hands up and get the CEM sorted properly, so I'm going to post it off to volvodiagnostic (appear to have good feedback on this very board: https://www.volvoforums.org.uk/showthread.php?t=143579) and get them to fix it all up. Hopefully that'll mean everything working next weekend...