C4Gp And The Faulty Handbrake Auto-Release....

[PeeVeeAh]

"Creeeeek!",

 

Looks a bit moribund here - but I've just had a spot of diagnostic luck that I needed to share.

 

My wife's 2008 C4GP VTi VTR+ developed a handbrake release fault.  However, it always worked with the manual release from the dash pull, but wouldn't auto-release when moving off as intended.  I booked it in, but being near to Xmas, the schedule was silly.  So decided to faultfind.  I checked the battery.

 

In the ignition position, the voltage was a bare 12.0V - which plummeted to well below 5V on startup - and then returned to a rather OTT 14.3 once the engine started.  I'm assuming the massive drop from a workable off-load voltage was because the battery had gone high impedance.  The engine was a bit less frisky on winding, but always did start okay.  However, for some reason it didn't detect sufficent volts for the ESP modes to be supported (including the auto brake release) so the battery was beyond serviceable limits.  It was the original battery and so at 7 years, was pretty remarkable, but my main issue is - why was there no system-generated warning that alluded to this simple battery failure?  Why was the auto handbrake release the first thing to fail before I knew what was going down?   Sure, there's always going to be a weakest link and therefore some operational feature that will be lost first.  But this was a fairly major thing to workaround!   No easy hillstarts in the manual version she's got.

 

Clearly, once Halfords had fitted one of their 'Silver' batteries, all came good!   I guess I'm just surprised that I've not seen any such story as mine on any Citroen service site.

 

We live and learn!  The vehicle has only done 25k miles, so I think we're going to find more such vagaries before the battery needs replacing again!

 

Cheers,

 

Pete.

[paul.h]

Welcome to the forum.

 

This is copied from a C4 Picasso handbook under the electric handbrake section:

If the parking brake malfunctions while applied or if the battery runs flat, an emergency release is always possible (see paragraph “Emergency unlockingâ€)

 

So fortunately if the battery voltage is down the handbrake can still be released, otherwise the car would be stuck. Citroens (and other makes) do not like a low voltage and the first sign is usually being slow to turn over on the starter motor and possibly lots of odd electrical faults (which you said you had - not turning over as quick and esp fault). With only 12 volts you were lucky to start the car. A good battery would be about 12.7 volts and about 14.4 volts when the engine is running if the alternator and wiring is good. Below 12.3 volts is considered as flat.

[PeeVeeAh]

Yes, thanks, I knew the brake release was possible, but I think you illustrated the point I was making - why doesn't a 12.0V off-load voltage make the dash panel light up with that specific warning, "Aye up!  Yer battery's knackered!" (or whatever the French might be!)   It's bizarre that there isn't a threshold warning that gives the nod to imminent battery replacement (or other charging deficit).

 

Or  - from the service industry's pov - maybe not?

 

Pete.

[paul.h]

Only car I've had that warned the battery was low was a 2003 C3 which beeped on starting but this was not specific to the battery and could be other things. The fact a car turns slowly on the starter is surely an adequate warning for most people.

 

On a C5 2001 to 2008 model there is a voltage gauge which shows if the voltage is down but if the battery is too low to start the car, as well as turn over very slowly on the starter, the headlights may flash and the front wipers move and the Service light may come on. Others have also reported an electric power steering pump not working and lots of other odd things, so if anything odd happens the first thing to do is check the battery and its connections.