Hi All,

my 2007 GTC has this recurring problem where after a few days the batteries are drained and it needs to be jumpstarted - and as we all know jumping a bentley that's dead isn't as fast as popping the hood, putting the clamps on and starting it...

There seems to be a small but sufficiently large parasitic draw on the system after the car has been switched off and locked. When driven daily its no problem but it seems to happen after a period of 5 days or more.

I have so far been able to find some information on the Ross-tech website on how to check millivolt drop over fuses and how to check if there IS, in fact, a parasitic draw, but to do this, I need to open all doors and trunk lid so I have access to the fuse boxes with the car in "sleep" mode i.e all lights off and the car thinking its in the garage, so to say.

can anyone perhaps help me in the right direction with the following:

- how to get the trunk "locked" in open position i.e. the trunk lights extinguished and dash not showing open trunk but the trunk physically open.
- if anyone has had this problem before, what the possible culprit was in terms of parasitic draw? i have the impression that the CD changer keeps working/revolving CD's even with the engine off... any experiences?

thanks in advance, gents!

 

I had a similar issue with my '05 Phaeton - when the ZAB unit starts to go (center console screen unit), it can do weird things. Mine left its small cooling fan running even after the car shuts off. It can be heard very faintly. Mine also kept trying to access the NAV CD unit when the car was off. Both resulted in a small draw that would drain the left-side battery. You can test for this by removing the ZAB fuse in the driver side fusebox.

Might have nothing to do with what's going on with yours, though. And BTW you know the starting trick, right? Usually no need to jump the car - if you twist the key all the way to the left, you bridge both batteries together and the car should start.

 

Thanks a Lot Samhain!

I will look for a fuse box diagram as its not in the owners manual booklet (I mean who doesn't put that sort of information in their user manual....) and find the ZAB fuse.

in case this turns out to be the problem, what did you do for permanent fix? replace the entertainment unit?

 

I don't have a fusebox diagram for my Continental, but my Phaeton dox says the ZAB fuse is a 10 amp fuse at position 17 in the fusebox located below the steering wheel. Position 17 would be the top row, second fuse from the right. The NAV unit, if you want to check that too, is at fuse position 33, which is 5 amp fuse in the 2nd row from top, 7th fuse from the right. Pulling those should allow you at least to check if the draw is coming from there.

Symptoms of a bad ZAB include rebooting, staying on after the car is shut off, display fails or transmits noise or lines. When mine died, it would also leave its internal fan on or continue to try and access the NAV drive after the car was off, causing the battery to drain.

NOS one is expensive for a Phaeton - about $2500 I think. Ebay used is about $600, but my ebay replacement also just failed. There's a guy in LA who refurbs them for about $500 but I can't find his contact info right now. If you need to go that way I'll look some more. He does Phaeton ZABs but the meat of the units is the same with G1 Continentals.

 

Hi and thanks again for your help. Yeah I am in touch with nav-tv for their ben-hur system but its ridiculously expensive... 2500USD...

So i did the millivolt drop test but there's no drop visible on any of the fuses. I did take the 5amp fuse out of the nav as its dated and not user anyway.

I did find fuse 85 broken... Any ideas? Its a 15amp.

Only problem i have now is that i cannot put my clamp ammeter on the left hand battery to see if there is any draw at all in sleep mode because I can't figure out how to let the trunk THINK its closed. The lights stay on so obviously there's draw from the 4 trunk lights...

Any ideas would be appreciated!

 

No idea on the trunk, but here's what my diagram says about fuse 85:

85 - SB85 - Fuse 85 (in fuse holder) 15 A - U3 - Left Rear Cigarette Lighter 30a (this is for the Phaeton so a chance it may not be the same as for a Continental)

 

Hello @Dubaitechie ,
I have a 2007 GTC with same parasitic draw issue. Wondering if you have made any discoveries as to what causes the draw? My car draws about 8 amps when shut off (with trunk open and trunk lite’s on). This is enough of a draw to run the big “house” battery completely down to zero in 4 or 5 days. I can always start the car if that happens using the “starter” battery. I normally leave the car parked connected to a charger to keep the house battery charged. So far, I have not been able to pinpoint what is drawing so much amperage when car is shut down. My mechanic guessed that the car has an after market GPS locator hidden in it. GPS locators are hidden when installed and very difficult to locate. These GPS units have a battery of their own, and if the battery fails, the car would keep trying to charge it while shut down. However, after talking to previous owner, I was unable to confirm that such a unit had ever been installed in the car. So I am back to where I started with no clue what is causing this large draw on the battery. Let me know if you make any progress on this problem. Thanks.