I have a 2001 bmw 740i. my battery was going bad I got a jump start monitor was working fine about two minutes later monitor went blank. the radio still works but it cuts out after a few minutes.if I turn the radio off then on again it starts working , but then cuts off again. I replaced the battery and the problem continues, I checked the fuses and they are good. also my navigation has stopped working

SOURCE: 2001 BMW 530I

I would recomend looking behind the left access cover in the trunk where the navigation computer is located. Inspect the area for any water intrusion, and if possible check the connections to the navigation computer for water or corrossion. the display colors are generated by the navigation computer via RGB lines. If the nav computer is cutting out, that would explain why a battery reset helps restore the picture.

SOURCE: Battery going dead 2001 BMW 330i

Whenever a car has this type of a problem, it is normally because of poor connections, belt slippage *severe*, or - very possibly, something is putting an excessive drain on the battery when it is not running.

My experiences have been to first check that ALL the connections are totally clean - especially check your battery posts and make sure they are tight with very good - surface-to-surface contact. Remove BOTH connectors on the posts and clean with battery post cleaning tool *wire brush* and then use the spray that stops / limits corrosion.

Are you sure that battery IS OK? Take it in for a load test - old batteries often deteriorate over time *sealed or not* and it just might be time for a new one. Get the biggest 1 that will fit in where it is held. More amperage *rating* is always better.

Poor connections often happen during cold weather season *expansion and contraction cause this*.

BAck to connections again - VISUALLY inspect ALL your cables/wires for discoloration. Connections need to be tight - end-to-end in the charging system. I am not sure if the car has a starting relay or not - and if so - where it IS located. THAT TOO is a problematic area due to poor connections that quite often, just may need to be cleaned.

Are you sure your alternator IS good --- are it's belt nice and tight- but not too tight? Speaking of the belt ... look on the inside track of the belt - has it been replaced recently or is the rubber in poor shape *splits, showing sign of extreme heat from slipping etc*. When you have a load test - that test alone will indicate whether it IS charging even if everything is running like A/C, radio, light, wipers. Check you gauge inside the car - IF it has one - and no matter what RPM ~ it should still be charging *showing positive charging - NOT discharging*. Lastly - the alternator OUTPUT -- is it the right one for that car - correct rating???

There are even more areas worthwhile checking ... but unless you have the correct tools and diagnostic equipment - it can be tough to nail-down the right specific problem. A lot of places *like Sears* will have that - and used to not charge for the diagnostic - because they wanted to sell you THEIR battery.

One more thing .... most cars will have some minor drain due to clocks running, alarm working and so on. HOWEVER - if a light *like an interior or truck light* remains on, that will give you a larger drain.

A battery should never go dead while driving - and your light *running lights* should always be bright .. are yours??????

Hope this helps!

Colin Stickland

• 22516 Answers
• Posted on Jul 26, 2009

SOURCE: 1995 BMW 740i worked on lights while cd were on,

i think that this vehicle has a factory immobilisor ,and this is your problem ,dealer only

SOURCE: My 2001 BMW 740i (E38)

This happened to my 06 325i, the navigation and instrument cluster displays are not controlled by the same computer, mine had to go back to the dealer for a reprogramming, hope this helps. let me know.

Ginko

• 19396 Answers
• Posted on Aug 08, 2011

SOURCE: 1994 BMW 740i with 222,000

Hi.

If it does turn over and electrical works, then the problem is unlikely the battery. You can try jump starting. If it cranks when jump-starting it may be a weak battery, starter motor or alternator, but I don't think that this is the problem.

Check if there is spark on all cylinders. Do a code scanning (this car is OBD1, you will need to do the scan at the dealer place or to find a BMW OBD1 tool- Universal OBD2 scanner will not work on a 1994 BMW). If the codes return misfire or mixture related errors check fuel pressure, check sensors and parts that determine the mixture (MAF/MAP, AIT, O2 sensors, IAC and EGR system), check the vacuum system for leaks and check the crank sensor.

Regards.

Ginko