5HP CAN bus transmission control

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AndreyB
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5HP CAN bus transmission control

Post by AndreyB »

Just made an early year 1995 BMW 750 v12 e38 friend in NJ - mine is "mk2 m73n/m73tu" his is just the orignal M73, the one with dual 88 pin ECU control.

He is 5HP-curious, looks like that early 90s vehicle is already fully CAN-bus transmission integration? We've made a mild attempt to hook to the CAN bus with no success.

Open question what baud rate is M73 CAN bus. Open question if we know anything about packet payload.
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Re: 5HP CAN bus transmission control

Post by AndreyB »

Weird

on the one hand some documents claim only TU models to have CAN but I've seen the CAN bus star connector with my own eyes
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Re: 5HP CAN bus transmission control

Post by AndreyB »

https://www.bimmerforums.com/forum/showthread.php?1681783-CANBUS-Baud-rate-E39&p=25000930#post25000930 is the winner - they claim 100kB

Well, weird, I've tried that :(
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Zeiss
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Re: 5HP CAN bus transmission control

Post by Zeiss »

Hey Andrey,

I will try to bring some light into the darkness. :)

So, first of all: 5HP is in every BMW (BMW called this gearbox A5S....., i.e. A5S560Z for 5HP with 560Nm) a CAN controlled gearbox, always and every time. 4hp (used with M70 i.e.) is always "digital controlled", GPIOs and PWM signals. So, we hold, 5HP is always CAN controlled.

Then, CAN-Bus in E38 is quite small, only DME (DME 1 and DME 2 from M73 or DME 1 from M62), AGS (Transmission Control Unit), Instrument Cluster, ASC/DSC (Dynamic Stabilization Control) and EML (if present, like by M73) communicates over CAN Bus.

Here you can the topology:
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Anyways, it is CAN HighSpeed. The speed, I don't know, could not find anything now in a hurry, but I'll look for it again later and let you know.

EDIT SAYS:
I found out, that BMW uses just two transfer rates on CAN: 100kbit/s and 500kbit/s. So, I would say: try it out :)
Regards,
Heinrich

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Re: 5HP CAN bus transmission control

Post by AndreyB »

Fun status update: said 5HP vehicle is lightly armored and has two starters just in case.
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