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Registered User
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CAN Bus failure
HELP!
My E36 Auto gearbox is running in “Safety” mode (staying in 3rd and 4th gear, Gearbox warning light on). I took it to the local BMW mechanic, diagnostic tester says “CAN Bus failure”. He said it would take a long time to track down and be expensive. Some details... According to the Electrical Troubleshooting Manual, for a 1997 318i, the DME, ECU and ABS should all be on the CAN bus, in my car only the DME and ECU are. Could this be the problem? The DME is M173 (Bosch part number 192 203 661). Resistance between the CAN High and CAN Low should be 60 ohm, on mine it is 22k (tested with ignition off) but the voltage on CAN High & Low tested to ground is correct (about 2.5 volts average, tested with ignition on) It’s been like this since I changed the engine (from M43 316 to M43 318) and have not been able to nut it out myself. My theory is that the M173 software is looking for the ABS and not finding it so shutting down the CAN Bus. Any ideas? The car is a South African assembled E36 316i sold new in New Zealand, has m43 318 engine fitted. |
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03-23-2011, 05:56 PM
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bostongrun
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That's your problem assembled in South Africa. Seriously did you swap in a new TCU as well? I have an 850 volvo and even though the transmission is mechnically identical to a replacement I bought but because there is a difference in TCU part numbers it goes right to limp mode.
These things are so complex that you can't just bolt these things together. You would have to rewrite the software to make them work. If something is missiing it goes right to limp mode. Sometimes if you know the value of a missing input you fool the computer by providing it with a facsiimile value. For example, many times people remove there catalytic converter which triggers a check engine light and possibly "open loop" however there are devices that provide a substitute input to the ECU. You really can't rewrite the software you can only trick it. Last edited by bostogrun; 03-23-2011 at 09:15 PM.. |
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03-23-2011, 08:27 PM
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Registered User
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Thanks for your reply Bostogrun.
Didn't change the TCU because I didn't change the transmission. I agree, don't want to change the software, but if it is expecting to talk to the ABS, I'll connect it to the ABS (assuming I have an ABS system that will talk CAN). Rather than trial and error, I was hoping someone might know if M173 software needs to be connected to the ABS. Pete Last edited by Kiwi Pete; 03-24-2011 at 12:45 AM.. |
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03-24-2011, 12:33 AM
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