Hopefully one of you guys can help, since november my JK has had 3 optima
yellow top batteries, it was running fine since i first had it, having now done
7500 miles since end of June.

First battery was completely dead, was only left over a weekend without being moved, (My YJ hasn't moved for 5 weeks but still starts again with a yellow top)wouldn't open the central locking with the fob, so back to the dealers it went, who replaced the battery. So 2 weeks later 2nd battery died, this time the electrics still worked but it wouldn't start, Jeep Assist service got it going and it was straight back to the dealers, this was 3 weeks ago. We get it back on Friday 7 December, come to start it Saturday morning and its dead again, battery #3, again we call Jeep Assist who get it started, do some checks and they say its not the battery and needs a thorough diagnostic, which you would have thought would have been done!!!

No one has any idea what might be wrong. Of course whenever it gets to the dealers, its been jump started at home and is running fine. Anyone had any similar experiences or know what fault code it might be??? Any suggestions would be appreciated.

Thanks in advance

Sarge

 

It's unlikely that it will set a DTC. It is most likely a parasitic draw (something drawing power when it shouldn't). The test for this is very easy, just have them put an amp meter on it when everythig is shut off. There will be a small draw from the onboard electronics (way under an amp) but to kill a battery that quick would be a much higher draw.

Once the draw is confirmed, finding the bad circuit is easy.

Good luck with the dealer.

 

Thanks for that - it would be great if it were a simple problem. However, the Jeep Assist guy who came to the house to start it did run a quick check and said there was no draw. He also tested the alternator and the starter and thought both were fine.

I just noticed the thread about the sentry key light and not starting. I wonder if its something to do with the immobiliser and/or alarm??

The dealer is completely baffled - thing is, there aren't many JKs in Britain. Patriots and Grands are going ok, but to see another Unlimited is rare. The dealers are moving a JK off display tomorrow to run a check on both together to see if there are any differences.

Strange thing is - it always seems to start when its at the dealers!

 

Have you added any electronics/electric items to the jeep?

It sounds like a circuit is energizing after the vehicle has been sitting for a while. Lincoln air suspensions were famous for this when they started to develop leaks (pump would run to keep the level up and kill the battery).

If the battery was dead everytime this happened, there is no way around it, something is draining the battery. If it is an itermittent issue, it will be more difficult to identify the draw.

Was the engine running when he did the draw test?

 

No electrics have been added to the vehicle its still stock and it was running when the checks were done, but also when it wasn't and all was fine.

Hopefully the dealers going to find something when it goes on their diagnostic machine just got to wait and see.

 

Dealer has now confirmed that its the starter motor, funny that when it went back the first time I asked could it be the starter?

Oh and they don't have one in stock, so likely to be fixed next week, they've only had it since 19 november, so 4 weeks good service?