Warning lights galore!

[Wildroot56]

When it rains it pours....

A few minutes ago I was driving and my battery light came on, the one right above where the "service engine soon" light is located. 10 minutes later my ABS light came on then a few minutes after that it switched to Trans Fail Safe....Sound like I need a new battery? I'm going to go check the code with a scanner a see what popped up.

[bstar]

Check alternator & battery. Watch video in DIY sction.

[Wildroot56]

P0343 and P1750....The P0343 is an ongoing problem that I don't think is related. The P1750 is new.

[bstar]

Watch the video. Unlock your cluster & check. These cars don't
like low voltage.

[cazal740i]

Sounds like the abs/dsc control module is fryed. Typical symptoms

[Qsilver7]

And read your owners manual for clarification of what the battery light means (it is so misunderstood )...the battery light illuminates when the alternator/charging system is NOT charging the battery. The battery is usually the victim in this case...not the culprit.

The other lights came on probably because the car started draining the battery especially if the alternator is failing...power needs to come from somewhere...and if the alternator isn't putting out as the car is running...the battery is forced to keep everything powered. Since it needs to be recharged and is NOT being recharged by a failing alternator...weired electrical gremlins can occur (like a lot of warning lights coming on) as the battery's voltage begins to drop as it's being drained of its "life force".

[Wildroot56]

Yeah, thats the thing. Is the bat low cause the Alt is not charging it or because the bats shot. I'm charging the battery now. How do I test the Alt? I can do the test on the video in DIY, but is that test for the battery or the Alt?

[Sphynx]

I also had many warning lights come on, and the trans go into fail safe mode when my alternator was in the process of dying (working sometimes, and other times not). Luckily for me, I also had to replace both batteries after the alternator incident .

Even though all you can get now are rebuilt alternators, they still are a little pricey (especially if you have to have someone else install it).

[Wildroot56]

Since the Bat Light came on first, that would tell me it's not the DCS unit. The Trans Fail Safe came on as a result of the Alt/Bat problem. Now I need to test the Alt somehow. How hard is it to replace the Alt? I could do it in about 30 minutes on a chevy, but knowing BMW it's probably a days job. I'm told they are water cooled....sounds expensive.

Once the bat is charged up I'm going to try to do the cluster test. If the voltage is low or dosen't hold steady, how do I know if it's due to a bad battery or if the Alt is not charging the batttery?

[Sphynx]

I'm told they are water cooled....sounds expensive.

I just pulled out my receipts and mine cost $547 and change (not including the $260 in labor to install it). That's for a rebuilt alternator...I wanted a new alternator but my mechanic said they were discontinued and rebuilt alternators are the only thing available.

I opted to have him do it because I really didn't feel like tearing into the car when it happened.

Here's a DIY write-up about replacing an alternator in a 740.
http://www.bimmerboard.com/forums/posts/355405

[Wildroot56]

I just pulled out my receipts and mine cost $547 and change (not including the $260 in labor to install it). That's for a rebuilt alternator...I wanted a new alternator but my mechanic said they were discontinued and rebuilt alternators are the only thing available.

I opted to have him do it because I really didn't feel like tearing into the car when it happened.

Here's a DIY write-up about replacing an alternator in a 740.
http://www.bimmerboard.com/forums/posts/355405

Thanks. I found these....

http://www.autopartswarehouse.com/pa...40i+alternator

And read your owners manual for clarification of what the battery light means (it is so misunderstood )...the battery light illuminates when the alternator/charging system is NOT charging the battery. The battery is usually the victim in this case...not the culprit.

The other lights came on probably because the car started draining the battery especially if the alternator is failing...power needs to come from somewhere...and if the alternator isn't putting out as the car is running...the battery is forced to keep everything powered. Since it needs to be recharged and is NOT being recharged by a failing alternator...weired electrical gremlins can occur (like a lot of warning lights coming on) as the battery's voltage begins to drop as it's being drained of its "life force".

I ran the cluster test after charging the battery and it held at 11.2-11.3 for awhile then started dropping down to 11.1, 11.0. 10.9 etc...at about 9.4 the ABS lights came on. I turned it off at that point and the voltage was too low to re-start. Now is that telling me the battery is shot and won't hold a charge or (more likely) the Alt is not charging. Looks like I need an Alternator huh?

I found these....look ok?
http://www.autopartswarehouse.com/pa...40i+alternator

[IcemanBHE]

Anything less than 12+VDC is TROUBLE in this car.

TIS says 12.3 VDC min IIRC.

You can check the voltage per the cluster test...if its say 11.8 VDC with the car off, and you start it, and the voltage does not increase to over 13 VDC, I think its alternator. Alternator should put out more voltage than when not running right?

But worst case its it might be both. Your battery might be old, and the failing alternator killed it off....

[Wildroot56]

Anything less than 12+VDC is TROUBLE in this car.

TIS says 12.3 VDC min IIRC.

You can check the voltage per the cluster test...if its say 11.8 VDC with the car off, and you start it, and the voltage does not increase to over 13 VDC, I think its alternator. Alternator should put out more voltage than when not running right?

But worst case its it might be both. Your battery might be old, and the failing alternator killed it off....

Yeah, the car should have been running alot higher just off the output of the alternator right? I only charged the battery for about an hour which got the car started but once the alternator started it should have run the voltage up to that 12.3 area and it never did. Also, when I ran the revs up the voltage started dropping.

The battery was purchased 8-08 so it's 1 1/2 years old so i'm leaning towards the Alternator. I'm going to finish re-charging it and take it to AutoZone and have them run a diagnostic on it just to be sure though. As expensive as these batteries are, I'd rather pony up for one of those than an Alt, but It's looking like an alternator.

[Qsilver7]

When you run TEST 9...if the ignition switch is in position 1 or 2 (engine NOT running)...your are looking at the BATTERY's voltage. if the engine is running, you are looking at the alternator/charging system.

Always check the battery first because if the engine is running (and up to 2 hours after shutting down)...you are looking at a battery that still has surface charge. You can see in the chart below...what the battery voltage should be. As others have intimated...your alternator should be putting out more that 12 volts (more like 12.8 volts and higher) if it is to keep the battery recharged.

[Wildroot56]

When you run TEST 9...if the ignition switch is in position 1 or 2 (engine NOT running)...your are looking at the BATTERY's voltage. if the engine is running, you are looking at the alternator/charging system.

Always check the battery first because if the engine is running (and up to 2 hours after shutting down)...you are looking at a battery that still has surface charge. You can see in the chart below...what the battery voltage should be. As others have intimated...your alternator should be putting out more that 12 volts (more like 12.8 volts and higher) if it is to keep the battery recharged.

Just the simple fact the during the test#9 and with the engine running the voltage was dropping... points to the alternator, correct? I charged the battery and had it tested at Autozone and it checked out OK.

[Qsilver7]

Just the simple fact the during the test#9 and with the engine running the voltage was dropping... points to the alternator, correct? I charged the battery and had it tested at Autozone and it checked out OK.

Yep.

[Wildroot56]

Yep.

Ok, so I removed the alt today and took it to Autozone to be tested....now they tell me it needed to be tested while ON the car. Wonderful. So I guess I'll take the plunge and order that Autoline alt for $294 from Autoparts Warehouse and I'll install on tues. Hopefully that was the problem!

Just an update on the DIY instructions....I only had to remove the fan itself. Left the clutch where it was. Alt came out fine. It was a little difficult to figure out where the alt separated from the housing but it all worked out.

[CLDean]

Just the simple fact the during the test#9 and with the engine running the voltage was dropping... points to the alternator, correct? I charged the battery and had it tested at Autozone and it checked out OK.

The easiest way to think of an electrical system for our cars or about anything else is that it's like a water mill. The battery represents the resevoir, and the alternator is the pump. If the pump doesn't work or doesn't pump enough water, eventually the resevoir will be drained.

[Wildroot56]

AHHH FRICKIN' WONDERFUL....

I was bolting the new alternator in and I snapped one of the 6 threaded screw hole "ears" off the lower timing case. I didn't know I was tightening down against a cast-metal housing. Should probably add that warning in the DIY write-up.

Never fails, you try to fix something on these cars and you wind up breaking something else.

[bstar]

Everything on these cars are light weight metal or plastic.

[Wildroot56]

Well now I'm wondering if there's something wrong with the new alternator. On the old one both surfaces seat flush when you push it in. On the new one when you push it in there's a gap between the two surfaces. That's what caused the "ear" to break, there was something on the new alternator that wouldn't allow for the two surfaces to come together and seat properly causing there to be a gap so when i tightened down I was forcing the two pieces together causing the threaded "ear" to bust off.

[bstar]

Do you have the old one to compare? Maybe the back isn't in the same clock
position as the old one?

[Wildroot56]

Naw sh*t, I figured out what I did wrong. The new one came with a gasket in it already, you could hardly see the thing. Then I was going to use the old gasket that seemed in good shape that was attached to the crankcase. So I was using two gaskets which was causing the gap which caused me to bust the "ear" off. Now I have to decide if i want to tackle removing the crankcase and replacing it myself. Couldn't find any DIY instructions anywhere.

[bstar]

Q might know where to find that info. Send him a PM.

[Wildroot56]

I did....