Intermittant starting problems

[fxstccj]

I bought a 2001 BMW M3 in August and having intermittent starting problems. I purchased the correct BMW battery yesterday and a new key from BMW 2 months ago. The car will start fine for a month or so and then will fail to start. All lights will come on but the engine will not turn over. I can push start the car and it will start right up and be fine for a couple of weeks and then it does the same thing all over again, or if it sits for a day or two it will start up again. The starter does not make any funny noises. Any help will be appreciated.

[dworthy]

Welcome to the Forum!

Just to be clear, when this happens, does the starter spin and the motor won't start? Or does the start not spin at all? If it is the latter, do you hear a clicking sound?

Have you checked for any codes stored?

[325bob]

Just clean/wiggle the battery terminals,and ground connections, a little dirt will block the massive amperage needed by starter, but allow everything else to function.

[fxstccj]

Welcome to the Forum!

Just to be clear, when this happens, does the starter spin and the motor won't start? Or does the start not spin at all? If it is the latter, do you hear a clicking sound?

Have you checked for any codes stored?

the starter doesspin or any clicking niose

- - - Updated - - -

no codes either

[bmwdirtracer]

Can you clarify that again please? The starter DOES spin, or the starter DOES NOT spin ?

[fxstccj]

sorry the starter does not spin or make any niose

[jclausen]

I would check faults in the ews system

[fxstccj]

thanks I will try it

[bmwdirtracer]

Since the car can be push-started, the issue isn't likely to be the EWS, unless it's a very rare internal wiring fault for the starter circuit. The EWS lives up above the pedals, left hand side, one 10mm plastic nut holding it - it's a white box the size of a pack of cigarettes. Pin #3 is the input from the ignition switch (black with blue stripe NOT blue with black stripe). Pin 1 at the EWS plug, black wire or black/yellow, is output to starter; if this is hot, the EWS is not the issue, and it's a bad starter, or bad connection at the starter.


Three possibilities come to mind:

Bad ignition switch.
Bad clutch switch.
Bad connection at the activation terminal of the starter.

Next time this happens:

1) Pull the clamshell cover off of the steering column (one plastic screw on top, a couple of screws on the bottom). Locate the black wire with a blue stripe (sometimes black with yellow stripe) coming out of the ignition switch. Put a test light on the terminal for that wire (you don't have to disconnect anything) Of course. connect the test light clamp to a good ground. (I use the door brake bolt). Turn key to start -- does the light illuminate? If so, try pushing in the clutch and starting the car. If it starts, we still have no culprit. If it still does not start, the ignition switch is NOT your problem.

2)Do you have an SMG transmission, or do you have three pedals? IF you have three pedals, I need to know how many wires go to your clutch switch - 3, or 4?

3) You need to get a test light or a wire with an alligator clamp to the activation terminal of the starter. This is difficult on an M3; probably best done from underneath the car, with the control arm rearward mount unbolted, and the wheel off. (This gives you extra room to see what you're doing. You'll likely want a mirror on a stick and a good flashlight) Hook the alligator clamp with wire to the terminal of the starter with the small black wire with yellow stripe. Unfortunately, there are TWO such wires; the difficult to reach TOP one is the one you want. (The other is an output). If you can clip your alligator wire to that terminal, then hook it to a test light, then have someone turn the key to start....if the light illuminates, and the engine is properly grounded.... and the main hot wire's bolt at the starter is tight and clean, you need a starter.

[fxstccj]

thanks sounds like the route to go

[fxstccj]

thanks it turn out to be a starter