[colman]

Hello,

Recently my 335xi suffered a no crank situation at the grocery store, after a two-try, long crank start about 30 minutes before. It was about 20deg F so I thought the initial poor start could have been due to the cold. Got towed home by a friend. Jump start ineffective.

The car still will not start 2 days later (waiting for a new starter to arrive). All ignition lights are OK and light up. I had some slow/long cranks for a couple of months here and there, but leading up the car was cranking well.

Battery voltage dropped while sitting and trying to start. Charged battery successfully (12.5v at jump points), tried to start again and battery voltage did not drop significantly afterward. The battery is less than a year old.

Grounded the engine to the chassis with a jumper cable to see if there was a bad ground causing the issue, no luck.

Then tested the signal wire to the starter, which lit up when trying to start. Does this *almost* guarantee the starter has gone out (125k miles) and it is not another issue? The battery was charged at this point, but the lights flickered and clock reset before the signal wire test start, which was new behavior that makes me curious about the battery as all other signs are good. It could be from the battery drain trying to start the car unsuccessfully though.

I would like to know what else to check while I wait for the starter/bolts to arrive. Of course, this thread may be useless if the new starter fixes it all, but at least there is a reference of how to eliminate possible causes. Thanks!

[dpaul]

Originally Posted by colman

Then tested the signal wire to the starter, which lit up when trying to start. Does this *almost* guarantee the starter has gone out (125k miles) and it is not another issue? The battery was charged at this point, but the lights flickered and clock reset before the signal wire test start, which was new behavior that makes me curious about the battery as all other signs are good. It could be from the battery drain trying to start the car unsuccessfully though.

Almost, as you've eliminated a CAS issue and the very common engine ground strap explanation.

However, here are the alternative possibilities I can think of:

1) As you noted there is still the possibility of a very weak battery. I'm guessing this does not account for your problem

2) Corrosion at the feedthough for the positive lead from the battery at the bottom of the battery compartment. Common enough. Testing for a positive lead problem is easy - check voltage right at the battery terminals in the trunk then check at the jumper terminal in the engine compartment. If they are not the same, worry about that feedthrough. A little water in the battery compartment will bring this on.

3) A formal possibility would be the strap from battery neg to chassis ground - the IBS device in series with it can crap out, not common. Just measure resistance from battery neg terminal to chassis ground

But the first thing I'd try, which you don't mention doing, is jumping with another car. If it starts, that eliminates the starter as the source of the problem (assuming you connect the negative cable to the engine block and the positive to the jumper terminal in the engine compartment). This test bypasses everything except the CAS signal which you know already know is good and the cable from jumper terminal to alternator and starter, which I've never heard of failing.

[colman]

It ended up being the starter. I did check the other items you have listed however. Thank you for the tips!