Help! Where's the Connection Point Between BMW Crankshaft Sensor and DME?

Technical Discussions
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Seeking Help on Crankshaft Sensor and DME Connections

I’ve been digging into the wiring for my BMW, specifically looking for the connection point between the crankshaft sensor and the DME (Digital Motor Electronics). I’m having some starting issues that I suspect might be related to the crankshaft position sensor or its connection to the DME.

What I’ve Found So Far

  • Wiring Diagrams: I’ve come across a few wiring diagrams, but they are a bit confusing. The color coding of the wires doesn’t seem to match what I have on my car.
  • Voltage Readings: I checked the voltage readings at the sensor, but I’m not sure what the expected readings should be. Can anyone provide some reference values?
  • Fault Codes: My OBD-II scanner is throwing some fault codes that reference the crankshaft sensor. I suspect it might not be sending the right signal to the DME.

Questions for the Community

  1. Where exactly can I find the connection point between the crankshaft sensor and the DME?
  2. What are the correct voltage readings I should be looking for?
  3. Any guidance on diagnosing these types of issues more effectively?

Additional Info

I drive a 2005 BMW 3 Series (E46), and I want to make sure I am on the right track before diving into more complex repairs. Any diagrams, tips, or experiences you could share would be greatly appreciated!

Thanks in advance for your help!

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I had the same issue with my BMW! The crankshaft sensor connects directly to the DME via a few key wires. Check the wiring schematic in your service manual for clarity!

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Thanks for the tip, allisonrachel! Is there a specific color code for those wires? I could really use a visual reference.

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Yes! The typical color code is often brown for ground and green for signal. There are variations, though, depending on the model year.

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Great info, jroth! I’ve been troubleshooting a no-start issue, so I need to confirm those wires are intact.

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If you’re having a no-start problem, it might also be worth checking the connectors at the DME. Corrosion can be a silent killer!

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Exactly! You may want to use some contact cleaner just to ensure good connectivity. It could save you a lot of headaches!

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I’ve heard that sometimes the sensors fail too. Any advice on diagnosing a faulty crankshaft sensor?

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You can test the sensor with a multimeter! It should have a resistance reading within a specific range. Always refer to your specific model’s specs.

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Thanks, rboyd! I’ll definitely give that a try. Just trying to figure out where I can find a reliable multimeter.

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You can find decent multimeters at any auto parts store or online. Just check the reviews before purchasing to make sure it’s reliable!

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Also, don’t forget to check the fuses. Sometimes it’s the simplest things that cause the biggest issues!

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So true! It always baffles me how a blown fuse can lead to such complex problems.

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On a lighter note, it’s almost like BMWs enjoy playing hide-and-seek with their problems!

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Haha, well said! As if they have a sense of humor about it!

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You might want to check the wiring harness between the crankshaft sensor and the DME. Common symptoms of a failing sensor include rough idling and stalling. Erratic performance could hint at connection issues.

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I’ve seen error codes like P0335 pop up when there’s a communication failure. Have you checked for any fault codes?

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Yes, definitely check those codes! I’ve had similar problems with my BMW. Debugging can be a chore, but it usually leads to either the sensor or the DME itself being faulty.

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I ran a scan, and I’m getting P0335. Going to inspect the sensor next. Thanks for the tip!

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When my crankshaft sensor died, my car would sometimes refuse to start. It’s frustrating, but if you feel it’s intermittent, that’s a telltale sign of a bad sensor or worse, a poor connection.

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