735iL Dead Battery - PLZ HELP!

VanKoppen · 01-19-2003, 05:31 AM

The battery died on my 1990 735iL

Is jump starting this car a good idea?

Can I use a mobile power pack to charge the car?

For the sake of argument, how do I know the battery is really dead?

prairieman · 01-19-2003, 08:06 AM

last question first - does anything electrical in nature on the car operate ? and there are lots and lots of electrical gadgets to play with... does the horn honk ?

jump starting - although I have heard horror stories on other message boards, the owner's manual provides instructions. The positive terminal is at the back of the engine compartment near the strut tower. The negative terminal is a much larger nut on the strut tower. The manual says to connect the positive cable to both cars, then the neg. Once the car has started, turn on headlights, blower and rear window defogger. Disconnect the negative cable first.

I don't see why a battery charger couldn't be used at the same connect points described above.

I don't own an iL (mine is a 735i), but I understand due to the power rear seats. it is a pain in the ass to access the battery. I know you have to move the passeneger rear seat lower cushion fully forward. So if you get it started - move that seat forward before you shut off the car.

good luck !

VanKoppen · 01-19-2003, 09:52 AM

The electrical components work, but barely. There's not enough juice in the battery to turn over the engine when I turn the key.

Although mine is a 735iL I've searched the back seat forever but have not found a rear seat adjuster, or a rear seat heater. I thought the car may have been badged incorrectly but I ran the VIN and it all checks out, any ideas?

prairieman · 01-19-2003, 03:18 PM

THAT's a good one.

I understood all iL's have adjustable rear seats. Rear heaters were optional. The adjuster would be obvious - it is on the lower front corner of each seat bottom.

It's possible a previous owner installed regular E32 rear seat bottoms. If that's the case - simply pull up the forward side of the lower cushion. There are two, maybe three spring clips (on a regular E32). Takes a bit of effort to overcome the clip.

Look at pictures of 735's and 750iL's on e-bay. At least one auction will have a picture of the back seats. You will see a switch at the front corner at the bottom of the seat.

Bear · 01-20-2003, 06:15 PM

If you truly have an il then the rear seat cushions will be separate items separated by the center arm rest. The adjusters (seat cushion and headrests) are located on the outside edge of the seat cushion, a verical knob for headrests and a horizontal one for cushions. If you have a single cushion, side to side, this is a i, not an il and the cushion will lift straight out albeit with lot of force.

autobonrun · autobonrun's Garage

I had a 90 735iL and now have a 93 740iL. Jump starting is not a problem if you follow the procedures outlined in the owners manual or in a repair manual.

The best way to know for certain that a battery is bad is to have a load test performed. I'd bet the problem is your battery. You will know if you have power seats because the controls will be on the side. If not, just grasp the front and yank upward. Power and heated seat release is similar but you have power connectors to release also. Be careful of your back muscle (ask me how I know) when you pull up on the seat bottom. Seat replacement is to just align the latches and press down.

Once you remove the battery, charge it up fully if you have a charger and take it to a battery store to have it load tested. Just because it will take a charge doesn't mean it will function under load. By charging it in advance, you can save yourself time at the shop because they have to charge it before they can perform the test.

If replacing the battery, it is important the vent be reconnected. You don't want sulphuric acid fumes inside the car. Keep the vent hose from the old battery in case the new one does not come with one. To my recollection, they do not.