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chicaneuk

Major battery drain.. ignition switch?

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Hi..

 

Back with another thread. Honestly I cannot believe the amount of gremlins I'm running into on this car.. I think at 207,000 miles virtually nothing on it has ever been changed and now I'm just starting to run into a multitude of 'common' problems.

 

So I've been having a pretty major battery drain whereby a couple of days with the car being left is enough to flatten the battery. Battery was an unknown make / model so I binned that and picked up a meaty Bosch 019 jobby from Costco however to my dismay I've noticed already the last few mornings, the car was very lethargic to crank over suggesting this battery was getting a major drain too. I had only just done a 120 mile drive a few days ago so it should be pretty well charged up! 

 

I've spent a bit of time troubleshooting this afternoon and found that the alternator seems to be charging the battery just fine, providing nearly 14v across the terminals with the engine running and all accessories on. 

 

I then followed some guides on trying to find out the cause of the battery drain by putting a multimeter inline on the negative terminal, locking the car and seeing what happens. I firstly tried faking all the doors being locked by closing all the door lock switches and then locking / alarming the car and could see no lights remained on anywhere so can rule those out. However I did notice that no matter how long I sat in the car, the current draw never dropped below about 1.8A (!). 

 

The interesting thing I found was that there was the sound of a little fan or motor humming from behind the climate control panel the entire time, no longer how long I left the car locked / untouched. If I pulled fuse number 4, it shut up, and the voltage drain dropped a little (down to about 1.4A) but still not down anywhere near to what it should be.

 

I've already replaced the FSU / hedgehog with a Meyle unit a few months ago and unplugging that again had no effect on the drain. 

 

I tried pulling a variety of other fuses such as the radio, CD changer, and didn't really get any improvement. 

 

My suspicion, from reading around, is that the car isn't going to 'sleep' properly and that a likely candidate is the ignition switch? I figure I best get one ordered. Would welcome any other thoughts.

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Worth checking too that one of your modules isn't causing a short.  You can check this within INPA, any modules that are on your car and return with "...No Response from Control Unit" could be suspect.

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If it's auto it's easy to check the light on shift lever panel. It should go out when the vehicle goes to sleep after 16 mins of locking. One culprit can be the Webasto. Try removing its fuse F47 in the trunk.

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Thanks! Car is a manual. I'm fairly sure it's just not going to sleep at all as stuff like the glovebox light continued to operate for ages after I'd locked the car, but I will have another go at it in the next few days and lock the car and leave it completely alone for at least 20 minutes and then check the power drain. 

 

I'm sure I tried pulling the Webasto fuse but didn't see the voltage drop - but again maybe it's that which is preventing the car from entering sleep mode at all so worth trying. 

 

Cheers. 

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For a possible sign of ignition switch switch issues. Try the visor test. Pull down the drivers visor and open the mirror, if anything happens then that could be the culprit.

 

Another one could be you final stage resistor to your heater, (Hedgehog) as its also known. A common problem.

 

Does your car have the optional phone? I've heard that the phone module could also be an issue! 

 

Best of luck :)

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No car phone.. and as mentioned, the FSU / hedgehog was replaced a couple of months ago. It was completely unplugged throughout these tests just to be sure so pretty sure I can rule it out! 

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Had a bit more of a look this morning. Sure enough, pulling the fuse for the Webasto seemed to result in a significant drop in power usage. I also tried disconnecting the auxiliary fan but that had no effect. 

 

The car seems to be going to sleep in so much as the power draw now drops to about 0.5 amps and stuff in the interior no longer seems to work after a period of time (e.g. glovebox light no longer comes on, etc) but even after 16 minutes the car never really drops into proper deep sleep as the power usage never seems to drop below about 0.45 amps. 

 

I shall keep investigating this afternoon I guess. Just been reading up that it's worth pulling fuse 56 as that's for the general module and a heap of other stuff so be interesting to see if the power usage drops properly with that pulled out.  If that works then I may look into a replacement GM3 module from eBay.. there seems to be plenty around for not much money - just need to try match up part numbers so there's no recoding needed. 

 

Previous owner wired in a tow bar and there's some aftermarket control box (and a heap of extra wiring for that) sitting in the boot I notice with a variety of wires going into it.. I'm not too hot on electronics but I can't help but wonder if that is causing problems. 

Edited by chicaneuk

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20 minutes ago, chicaneuk said:

Had a bit more of a look this morning. Sure enough, pulling the fuse for the Webasto seemed to result in a significant drop in power usage. I also tried disconnecting the auxiliary fan but that had no effect. 

 

The car seems to be going to sleep in so much as the power draw now drops to about 0.5 amps and stuff in the interior no longer seems to work after a period of time (e.g. glovebox light no longer comes on, etc) but even after 16 minutes the car never really drops into proper deep sleep as the power usage never seems to drop below about 0.45 amps. 

 

I shall keep investigating this afternoon I guess. Just been reading up that it's worth pulling fuse 56 as that's for the general module and a heap of other stuff so be interesting to see if the power usage drops properly with that pulled out.  If that works then I may look into a replacement GM3 module from eBay.. there seems to be plenty around for not much money - just need to try match up part numbers so there's no recoding needed. 

 

Previous owner wired in a tow bar and there's some aftermarket control box (and a heap of extra wiring for that) sitting in the boot I notice with a variety of wires going into it.. I'm not too hot on electronics but I can't help but wonder if that is causing problems. 

 

I suspect @Clavurion can confirm but there may be benefit it disconnecting the webasto from the KBus, not just removing the fuse as I suspect the GM will be constantly trying to read from it even with no power going to it.

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