Door unlock and Power steering issues could they be Battery Related ?

[DarrenW]

Hi All,

I have two intermittent problems and was wondering if they could be battery related. Before I part with my hard earned I thought I'd ask the wider audience for their thoughts

Remote door unlocking
Whilst the remote will unlock the drivers door every time it will only intermittently unlock the rest of them with a second push. Have to lock and unlock several times to get the other doors to unlock

Power Steering
Sometimes when I first start up the powersteering is heavy (but I believe it was still power assisted) I think it's how it should feel once the car is moving. If I turn the car off and restart it will be very light.

Now the battery.....
I've recently fitted dual voltage gauges to monitor my main and aux battery. When I'm driving I can see the alternator is putting out 13.9-14.0 volts. After a long drive and approx 30mins of rest my Aux battery reads 12.6 volts but my main battery reads 11.9-12.0 volts. The car turns over fine and doesn't exhibit any of the symptoms I've known in the past for a battery on the way out. Also I don't have a battery drain issue as it is fine to start even if it's been left for 2 weeks

I don't know when the battery was last changed, it's not mentioned in the service records I have.

Could my issues be related to the main batt voltage ?
Should my main batt rest voltage be closer to my Aux ?

Thanks in advance

[rar110]

Yep I would start by getting the cranking battery load tested.

[harlie]

Battery will have nothing to do with heavy power steering - it is hydraulic, belt driven pump to a ram. Might have something to do with low fluid pulling down some air or old fluid - or something much more expensive.

The unlock seems odd too. If the first unlock works why does the 2nd not? Does this happen on both keys or just yours? The 2 key press unlock was the first "feature" I disabled when I got mine so I can't say that mine has never done that.

In my 9 year experience owning a 2004, the first sign of a struggling battery is the "HDC Inactive" message on startup. These cars are super sensitive to voltage and if the battery is struggling you will get messages immediately after starting the engine which is when the battery has dropped to its lowest voltage.

The problem you have trying to get a "resting" voltage reading is that the rangie never "rests". Yes the primary battery resting voltage should be close to the aux (depending on battery type - my aux is a gel battery which will hold 13.0v for a couple days - where a calcium battery will be ~12.6-12.8) HOWEVER to get an accurate resting reading you will need to disconnect the battery as there is so much crap running long after the ignition is turned off that you will always get a lower reading - especially if you take it within a couple minutes of opening a door.

As Mr Rar suggests, it is easy to get it load tested, but I doubt the the battery is the cause here.

[RangieBit]

I'm actually of a different view to Harlie on this (sorry Harlie).

Here's my reasoning. Harlie is correct in that the power steering is a standard pulley and pump system for assistance with the steering. The thing is that it is speed sensitive. That is, lots of assist at parking speeds where the wheels need to to turn through greater angles and are of course traveling slowly so their static frictional coefficient has more impact. Less assistance at normal road speeds where the wheels are easier to turn when they are rotating much quicker. Since the speed sensor system is electronic this could be "gremlin-ised" by battery troubles.

I recently had an older battery drop an entire cell which meant that it held charge pretty well in the remaining cells but didn't give much voltage consistency as the other cells tried to compensate for the dead cell whenever the battery came under load. Caused some weird electrical quirks I can assure you. So it's possible voltage issues could be messing with the BCU and causing strange quirks with lock/unlock cycles. Could just be a flaky battery in the remote too :D

None of this is to say definitively that any of this is the cause, just to my mind not ruling it out as starter battery is all.

As has been mentioned previously, load testing the battery will give you the best indication (it's what flagged my dead cell).

Hope you track down the cause of your woes Darren.

Cheers,

[harlie]

No appologies required mr Bit - I've been wrong many times on many subjects in the past....