Everything works but it still won't go.

Make sure battery has full charge and connections good. Use a digital multimeter across battery posts, everything off. The generic spec for a full charge is around 12.6 volts. At the moment, I don't know why you can't jump it? Check voltage at fuse circuits in fuse box, use a test light. Some fuses hot all the time, some go hot with key on. If ignition feed is a problem, have to check feed to and from ignition switch.
At starter motor, two voltage circuits, one comes from battery, hot all the time. The other voltage circuit goes hot with key in the crank position and is wired through neutral switch, depending on the tranny. The starter motor grounds through engine block. Any testing make sure tranny is in park or neutral and the parking brake is set.

Did you check power an grounds using voltage drop testing , did you check battery voltage an computer control at the starter motor relay in the under hood fuse / relay box ? Instead of guessing you need to learn how to use a DVOM - digital volt ohm meter an test ! The powertrain control module controls the starter motor operation ! Starter Voltage Drop VEHICLE RELAYS Operation Diagnosis ,If you pull the relay an jump pin's 30 & 87 the starter should crank ,test the circuit starter motor side ! Pins 85 & 86 are the control side ., Pin 85 or 86 forget which one has battery voltage with the key on . The one with out voltage is control from the engine computer ! Also if the anti theft system is active it wont start !

check on the fuse box, am sure that a starter fuse is blown. the alternator might be the causer. as you said you changed it not so long. When you find out the fuse are ok, check also the solnoid wire on the starter motor beside the main wire, when that is good then might be the carbon brushes are won need to be replaced

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

Check the fuse first thing. If the fuse it good then either the blower motor speed control switch, blower motor resistor pack, or the blower motor itself is bad. Normally the speed control switch rarely goes bad. If some of the speeds did not work prior to total failure then the resistor pack is bad. If that is not the case then apply 12 volts directly to the blower motor to see if it is good. If it runs suspect the resistor pack as the culprit.

The single most cause of no motor output is failure of the DC motor control. Before you attempt to determine if it is the control, you must first rule out simple things.
1) Make sure you have power in the wall outlet by plugging in a lamp, etc. into the same outlet the treadmill is plugged into to test. Plug it in the exact same receptacle. Sometimes in an outlet one receptacle will work and the other won't.
2) Make sure any breakers are fuses that may have tripped or blown have been reset or replaced. Your local Radio Shack can help you test the fuses. Use the same type of fuse. Changing the value of the fuse can be dangerous or cause a fire.
3) Make sure the power switch is turned on and the safety key is inserted into the console if you have a safety key.
4) Look for any test lights on the power boards beneath the motor hood. Use caution when removing the motor hood because you may still have electricity in the motor area even if the treadmill is unplugged.
5) Test for a motor control failure. Typically if you have a failure, the treadmill will continue to turn on and operate normally until you try to input speed. If the treadmill operates on what we call a closed-loop system, it will give you some type of error message. If it operates on an open-loop system, the computer will run normally but the motor will not turn.
6) If you have a multimeter, you can test to make sure you have DC output from the controller spades. First make sure you have 120 VAC going in to the controller. On most controls, you can use a linear taper potentiometer or jump the W and H circuits of the control with an insulated wire or insulated pliers and apply AC voltage. The DC output spades should output DC voltage if the control is good.
7)
Cordless drill battery- get a fully-charged, 18 volt (preferred) cordless drill battery and on most treadmills connect the red and black motor leads to the battery (some have different colors but if you have two wires and get it hooked up backwards, the motor will just run backwards and won’t be harmed). If good, the motor should operate at about 1 MPH

Unplug your treadmill and remove motor shroud ,locate Motor control board their a series of LEDs . Now without getting on treadmill hit start look down and you should a light starting to flicker this is your PWM signal, t the upper console sends a signal to the lower board and instructs the motor to start. This tells me that the upper board and cable are functioning properly and our problem is either the board or motor.
DC motors can be easily tested in a number of ways. Many times a motor is replaced only to find another problem exists so be sure to test the motor if you think it is a problem. Methods to test a motor: 1) Cordless drill battery- get a fully-charged, 18 volt (preferred) cordless drill battery and on most treadmills connect the red and black motor leads to the battery (some have different colors but if you have two wires and get it hooked up backwards, the motor will just run backwards and won’t be harmed). If good, the motor should operate at about 1 MPH. 2) Car battery- these are 12VDC high amp batteries so the motor will turn slowly but you can walk on the belt. Always be careful with battery acid on these things so we don’t recommend bringing them in the house…take the treadmill to the battery.
If the motor test good then all fingers point to the Motor Control Board replace the board. When was the last time lubricated the running deck?
Answer: Never ! Then I suggest you purchase lubricant and apply it on the deck about 75% to 85% of the problems are belt and deck related.

3 causes: 1 blower motor inactive 2 dash switch 3 speed control.
Check blower motor by jumping 12 volts to power wire.Also jump ground side to be sure wiring is viable. If motor is operating then check speed control. Located in duct work under hood.5 wire connector. Batt voltage should be present at one wire.Apply test lite to all wires in connector and see if speeds are there. If not then control is bad. If o/k then dash switch is likely to blame. The dash switch controls what wires from the speed control are to be grounded. It does not control voltage to the motor but controls what wires are to be grounded to control fan speeds.PS check your fuses with a test lite to be sure Good luck Moe