325ix Not Charging -- Stumped

[AWDBOB]

Fellow R3Vers, I am in need of some help in diagnostics.

Preface:

I have been experiencing some odd wiring issues since I purchased the car. The radio and tachometer will only work with the lights on. I figured this is just something with the way the power was wired in, but never looked into it.

The problem:

I was driving home the other night, and the radio started to blink like crazy, and eventually shut off and wouldn't power back on. In making the next right turn, I noticed my turn signals blinking ridiculously fast (not burnt out bulb fast). Following that, the lights began to dim, etc, so naturally I tested to see if the car was charging, and it was not. I replaced the alternator only to find out that the car was still not charging afterwords.

I then found out about the 'battery warning bulb' going out, and how if that happens, the charging circuit is not complete, and thus will not allow the alternator to do its job. I proceeded to pull the cluster and test the bulb; it wasn't bad.

Now, I'm stumped. New alternator (tested good), good battery light, car won't charge.

Radio/tach is back to normal after I put the battery on the charger, as in it only works with the lights on.

One thing I noticed was that the car was missing a low-beam bulb in the cluster, and I'm wondering if that could have something to do with the odd 'lights on radio/tach on' deal.

However, I'm more concerned at the moment about why the car won't charge, and quite frankly, I'm out of ideas.

Thanks in advance.

[spdracrm3]

charging issue

power has to flow thru the bulb or bypass resistor to the alt to start and create/excite the magnetic field and start the charging process once the alt is spinning fast enough so even if the bulb is burned out there is a resistor bypassing it to allow voltage at the cluster thru the bulb/resistor circuit so it will charge (the bulb is grounded thru the alt windings with key off and engine not running ,this lights the bulb ,once the alt is spinning and charging (producing voltage) it supplies power up to the bulb at the cluster and a bulb with power to both sides will turn off so you know its charging) . so you need to check the circuit completely ,download the 89 IX ETM from http://wedophones.com/BMWManualsLead.htm and go to "charge diagram (1230-0) you will see power comes direct from battery thru the power distribution box with no fuse to the ign switch (red wire),thru the switch when turned to run/start position, out the switch on the green wire to the cluster ,thru the bulb circuit ,out of the cluster to the Alt on a blue wire (which also goes to pin 12 in the diag connector),if you have a test light or DVOM check voltage at all connectors and switches starting with the easiest to access and see if you have voltage present ,if not follow the circuit back to trace problem area, also make sure alt is grounded properly should be a brown or braided wire from alt case to engine block .can be a bit of a pain but satisfying once solved. from the other symptoms your describing i would start at the ign switch for sure...

there is no "low beam " bulb in the cluster (only high beam) maybe its the fog lamp bulb thats missing which wont affect other lights

[AWDBOB]

power has to flow thru the bulb or bypass resistor to the alt to start and create/excite the magnetic field and start the charging process once the alt is spinning fast enough so even if the bulb is burned out there is a resistor bypassing it to allow voltage at the cluster thru the bulb/resistor circuit so it will charge (the bulb is grounded thru the alt windings with key off and engine not running ,this lights the bulb ,once the alt is spinning and charging (producing voltage) it supplies power up to the bulb at the cluster and a bulb with power to both sides will turn off so you know its charging) . so you need to check the circuit completely ,download the 89 IX ETM from http://wedophones.com/BMWManualsLead.htm and go to "charge diagram (1230-0) you will see power comes direct from battery thru the power distribution box with no fuse to the ign switch (red wire),thru the switch when turned to run/start position, out the switch on the green wire to the cluster ,thru the bulb circuit ,out of the cluster to the Alt on a blue wire (which also goes to pin 12 in the diag connector),if you have a test light or DVOM check voltage at all connectors and switches starting with the easiest to access and see if you have voltage present ,if not follow the circuit back to trace problem area, also make sure alt is grounded properly should be a brown or braided wire from alt case to engine block .can be a bit of a pain but satisfying once solved. from the other symptoms your describing i would start at the ign switch for sure...

there is no "low beam " bulb in the cluster (only high beam) maybe its the fog lamp bulb thats missing which wont affect other lights

That was all super helpful, man.

I did the most simple thing first: Ground the alternator with a jumper wire.

Sure enough, she started charging! The alt I got didn't have bushings or anything so I could only assume that it would still ground on the brackets, but apparently such was not the case.

I looked further into the 'missing bulb' and it appears that it was just there for an option that I don't have, so I should be good to go.

Now to figure out why the tach/radio only work with the light on. The wiring looks normal, and the only thing that looks out of place is a white wire that's spliced from the drivers side firewall harness that is now power for the radio... I just don't know where it went before it was cut.

[E30NJ]

mine does the same thing sometimes but mostly with the tailights. e30 problems...