[MartynT]

Before I write to Volvo about this I'm interested to know if anyone has experienced this?

Saturday 9 July - dash display didn't light up, steering lock on, engine didn't start. I opened bonnet, checked the battery terminals were tight (they were). Got back to drivers seat and everything was fine (clock went to 00:00).
Tuesday 12 July - while driving the dashboard display went out, engine died and steering lock engaged. Fortunately we were in the countryside and the road was reasonably quiet. After directing traffic around the car, I checked the battery again and it seemed OK. Engine restarted, clock was zeroed, car ran properly.
Today 19 July - when going to start the car, the same occurred while parked up.

The battery is 6 months old and start stop functions (so assume battery itself is fine). I was wondering if the zeroing of the clock indicates a main fuse it toast? My main concern is the steering lock engaging while I was driving.

Thoughts anyone? I'm contacting the DVSA and Volvo.

 

[RS3100]

First port of call should be a check for fault codes. If any have been logged, they should give an indication of the component or area involved. Without checking that first, it could be like unnecessarily looking for a needle in a haystack.

Apart from that: key reader unit behind the dash key slot if not keyless start. Faulty key. CEM multi-pin connector behind the glovebox. Multi-pin connector in the footwell beneath the carpet. But reading fault codes could save a lot of time.

The steering lock is electronic. If the car receives an ignition off signal the lock will engage.

 

[DaveC]

Don't assume the battery is fine just by 'feeling' the connections are tight, remove the battery terminals and clean the posts and insides of the terminals with emery paper and then refit, see where you go from there, there is every possibility of a poor/corroded/hot intermittent connection.
That would be my 1st port of call before going any further.

 

[MartynT]

Thanks - I'll check as suggested and feed back what I learn. Don't have VIDA/DICE but do have an OBD2 reader - I expect Volvo has to comply with basic standards for the comms??

 

[RS3100]

Thanks - I'll check as suggested and feed back what I learn. Don't have VIDA/DICE but do have an OBD2 reader - I expect Volvo has to comply with basic standards for the comms??

Engine and drivetrain, yes. All are standardized across all manufacturers selling cars in Europe to EOBD, but you'll need a Volvo specific or multi-make all systems scanner to look for codes from all other ECUs, such as the CEM. That's not just Volvo, all manufacturers implement their own diagnostics for non-EOBD systems. iCarSoft VOL devices are probably amongst the cheapest Volvo specific all system diagnostic tools, but still more than you'd likely pay a garage for a full check.

I'm not sure if CarScannerPro for Android can do multi systems on Volvos with the Volvo addon, but you'd need a separate bluetooth dongle to connect it to the car.

The CEM controls, or communicates with other modules that control things like battery monitoring, and there's a separate steering module. I would guess the CEM is unfortunately likely to be where you'd find pertinent codes if there are any.

 

[R1916V]

There is a BMS sensor on the negative battery terminal.
It measures and monitors in/out current to battery, voltage and the temperature of the battery.
All the current flows trough this sensor and if it has some defect, it can plays such crazy problems.
Also, it is possible that terminals on battery to be fine, but internally in the battery the links between the individual 6 battery cells to have some problem and to break the circuit from time to time, or to short some cell. This will follow to unexpected drop in current/voltage and can confuse car's electronics.

About battery sensor can read here:

Battery sensor: how it works, problems, checking, battery replacement

What is a battery sensor in a car, problems, checking, replacement; changing a battery with a battery sensor

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