Just doing a quick double check here.

[BrassDrummer]

So the other day I was driving my car (1989 325i M20) and I noticed my lights started getting pretty dim, and my windshield wipers were moving really slow, however the car wasn't dying if I kept the RPM's above 1500. When I got home, I turned off the car, and when I tried to start it again, nothing. No starter or anything, but all of my interior lights worked fine. My Headlights were a little dim, and my wipers still worked slow.

The next day, I went to try and start it, and it fired up right away, ran ok for a little bit, and then started to get the same symptoms. Turned off the car, and tried to start it again, nothing.

This sounds to me like the alternator is just about dead. Probably a diode or something went out. I don't have any of my testing equipment at home, because I leave that at work.

I'm just checking to see if any of you guys have had any issues like this so I can comfortably agree with myself in saying that the alternator is bad...Because shits expensive.

[AndrewBird]

Either a dead battery or a bad alternator. Only way to tell is to check the voltage at the battery with the car running. Should be ~14volts. If it isn't, then the problem is your alternator. If it is, then it's your battery.

[BrassDrummer]

Either a dead battery or a bad alternator. Only way to tell is to check the voltage at the battery with the car running. Should be ~14volts. If it isn't, then the problem is your alternator. If it is, then it's your battery.

Kinda figured. I was planning on replacing both since the battery is getting to that age anyways, and with 200,000 miles, and the last alternator being put in sometime before 2006 (Car was sitting for awhile before I got it) I think its time for the alternator too. Thanks!

[Gregs///M]

If your battery is 5 years or older, replace it. However, once a battery goes dead, it wont crank the engine over.

Keep an eye on the alternator and check its output asap.

[TurboJake]

This is also symptomatic of a ground issue.

Check your engine and chassis grounds. The oil pan to frame rail, battery to chassis, and the passenger strut tower connections

[stamar]

So the other day I was driving my car (1989 325i M20) and I noticed my lights started getting pretty dim, and my windshield wipers were moving really slow, however the car wasn't dying if I kept the RPM's above 1500. When I got home, I turned off the car, and when I tried to start it again, nothing. No starter or anything, but all of my interior lights worked fine. My Headlights were a little dim, and my wipers still worked slow.

The next day, I went to try and start it, and it fired up right away, ran ok for a little bit, and then started to get the same symptoms. Turned off the car, and tried to start it again, nothing.

This sounds to me like the alternator is just about dead. Probably a diode or something went out. I don't have any of my testing equipment at home, because I leave that at work.

I'm just checking to see if any of you guys have had any issues like this so I can comfortably agree with myself in saying that the alternator is bad...Because shits expensive.

your symptoms are definitely the alternator.

The belt could need tightening.


alternators do sometimes live long enough to wear out the brushes. so that is possible. just lived a long life and its time for a new one.

[paperplane94]

your symptoms are definitely the alternator.

The belt could need tightening.


Alternators do sometimes live long enough to wear out the brushes. So that is possible. Just lived a long life and its time for a new one.

^+1

[stamar]

I dont have the link for you ready, but I saw on this forum someone linking ebay bosch rebuilds with higher amps for cheap no core.

In general they are for big pimpin car audio but I think older cars appreciate upgrading the alternator amps due to higher resistance of older wires.

[BrassDrummer]

Ok, so an update on this. I agreed with all of you guys. I replaced the ground from the oil pan to the frame, replaced the alternator, and replaced the battery. The car ran fine for about 20-30 miles of in town driving. Then the same stuff started happening. Cars lights start dimming, and eventually the engine dies. Has anyone else had any issues like this? This is frustrating because it should be working. My grounds from my passenger strut tower are good, my rear battery grounds and ground straps are good. I even disconnected the amp I have in there (Small 4 channel 50W amp for my speakers, no subs or anything extreme) I don't understand this at all. are there any connectors from the B+ on the battery to the starter? Or does anybody have any other suggestions on this issue?

I have an open shop day tomorrow at work, so I can hopefully get some real diag on it, but I just need to get it there first haha

[stamar]

wow, we have a problem with the wiring from the alternator to the battery....

Ya I need to see the power output right on the battery. Most auto part stores will do it for free or get a ohm meter from harbor freight.


It is entirely possibly you installed a bad alternator. That has happened to me.

even your 2nd symptoms are of a bad alternator.

make sure you have the belt on tight.

If you were to run a car with no alternator, and just use the battery, it would run out in about 30 miles. So youre not charging up....if the alternator is good theres something wrong with a wire.

[BrassDrummer]

wow, we have a problem with the wiring from the alternator to the battery....

Ya I need to see the power output right on the battery. Most auto part stores will do it for free or get a ohm meter from harbor freight.


It is entirely possibly you installed a bad alternator. That has happened to me.

even your 2nd symptoms are of a bad alternator.

make sure you have the belt on tight.

If you were to run a car with no alternator, and just use the battery, it would run out in about 30 miles. So youre not charging up....if the alternator is good theres something wrong with a wire.

Check this out, Just found this on another forum, and I noticed I started having these problems after I replaced my instrument cluster with one from the junkyard.

This is from a user at Bimmerforums
also you have an 85 if the alt light goes bad it might not charge correctly if the alt tested good. not sure when the year they added the resistor so if bulb got bad car would still charge."

I will check this out tonight and see if it fixes things.
"

[BrassDrummer]

Fixed it!

Sure enough, replaced the battery check light bulb with one of my instrument cluster light..light bulbs, and sure enough, car fires right up, and doesn't die or anything. Looks like I grabbed an older cluster. Really good to know though for future diags!

[stamar]

Oh wow that is something I have never heard of in any car ( and I used to work in a used car lot)

Thats a world class terrible design.......an alternator that goes out with the bulb.


terrible.


Im sorry we had never heard of that I definitely have never heard of that. Thats so terrible you would win a lawsuit.

At least I can take credit for figuring it was in the wiring to the alternator from your description but I have never heard of a .... fused bulb....

[paperplane94]

"Idiot Light"

[jlevie]

The alternator warning bulb is the source of exciter power for the alternator. If the bulb is bad there will not be exciter power to the alternator and thus it won't charge properly. This configuration is a lot more common than you might think, and not just on E30's. Though very late E30 clusters, and many other implementations, also include a bypass resistor to make sure that exciter power is available if the bulb burns out.