Siemens MS43 DME

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Siemens MS43
Unit	Engine computer (DME)
Cars	E46 six-cylinders, 2001-2003
CPU	Infineon C167
Software read	MS430069
Gearbox messages	`0x43D` AMT1, `0x43F` EGS1
Faults covered	134, 129

The engine computer of the 2001-2003 E46 six-cylinders. This page covers its side of an automated gearbox: the 0x43D frame, fault 134, and how it learns which gearbox it has. Read from software MS430069 with a stock calibration.

CAN messages

The DME's message objects fix what it can hear. Anything else on the bus is ignored, under any name. firmware

Direction	Identifiers
Receives	`0x43F` EGS1 (automatic), `0x613` and `0x615` (cluster), `0x153` and `0x1F3` (DSC), `0x43D` AMT1 (automated manual), `0x1F5` (steering angle)
Sends	`0x316`, `0x329`, `0x545`

Which gearbox it thinks it has

The DME is not coded for a gearbox and never reads the vehicle order. It learns the variant from the bus and keeps it.

One bit is all diagnostics show. ECU_CONFIG's EGS_VORHANDEN and GE_VORHANDEN are the same bit (response byte 3, mask 0x10): a CAN gearbox is present. Nothing in the diagnostic description says whether it is an automatic or an automated manual, and no job writes it. BMW data
With 0x43F on the bus it learns a CAN gearbox; take 0x43F away, clear the learned variants with ADAPT_VARIANTEN_LOESCHEN, and after a power cycle the bit reads 0 again. field report
Once learned it is kept until ADAPT_VARIANTEN_LOESCHEN clears it. field report

Fault 134

"SSG-Eingriff unplausibel" is three monitors under one code. The fault-type byte says which. BMW data

Type	Text	OBD
`0x7D`	SSG-Eingriff unplausibel: the frame's state is impossible	P1670
`0x7E`	SSG-Moment unplausibel: the torque request does not fit	P1653
`0x7F`	Timeout Message Counter: the alive counter stopped	P1654

A missing 0x43D is a different fault, 129 "Timeout SSG-Botschaft". So 134 means the frame arrives and its content is rejected.

The freeze frame stores STATE_AMT (0x8F), STATE_ERR_AMT (0x90), the DME's own torque TQI (0x91) and the gearbox's torque TQI_AMT (0x92). The two torques are stored at 4.01176 Nm per bit, which is the freeze frame's scale, not the frame's. BMW data

STATE_ERR_AMT

One routine writes it every 10 ms from the last 0x43D. The fault sets after about 0.2 s in an error state. firmware

Value	Cause
`0x00`	Plausible
`0x01`	No shift flagged, but STATE_AMT is not 0, or the torque byte is 10 Nm or more
`0x11`	Shift flagged with STATE_AMT 0 and byte 0 bit 7 clear
`0x10`	Shift flagged, STATE_AMT 0, bit 7 set, but torque above 0 or road speed above about 15 km/h
`0x20`	Shift state held too long: state 1 or 3 over 2.3 s, state 2 over 5.8 s
`0x21`	State 1 or 3: requested torque more than 60 Nm above actual for over 0.35 s
`0x22`	State 2: clutch field 3 for over 0.2 s
`0x30`	Byte 6 checksum wrong
`0x40`	Frame missing
`0x50`	Counter unchanged for 0.25 s

Other values, such as 0x48, are not written by this routine.

The 0x43D frame

As the DME reads it. firmware

Byte	Bits	Meaning
0	0-2	Gear
0	3	LV_GS, shift in progress
0	5-6	STATE_AMT, the shift state (read as `(byte0 >> 5) & 3`)
0	7	Checked together with LV_GS, see 0x10 and 0x11 above
3	all	Requested torque, absolute, 1.5625 Nm per bit (400 Nm full scale)
5	0	LV_GP, gearbox protection: invokes the road-speed limit c_vs_max_amt
5	2-5	Alive counter, one step per frame
5	6-7	Clutch state
6	all	Checksum: `0xFF - min(0xFF, byte3 + counter)`

When no shift is in progress

Every 10 ms. This clears fault 134 with the engine off and running. field report

Byte 0: gear in bits 0-2, LV_GS 0, STATE_AMT 0.
Byte 3: 0x00. A "neutral" 0xFF reads as about 398 Nm and gives a permanent 0x01.
Byte 5: the counter in bits 2-5, the clutch state in bits 6-7.
Byte 6: 0xFF minus the counter, since byte 3 is 0.

During a shift

Byte 0 = gear | 0x08 | (STATE_AMT << 5), with STATE_AMT 1, 2 or 3. LV_GS and STATE_AMT go up together and down together; LV_GS on its own is never valid.
Byte 3 = the torque wanted, never more than 60 Nm above what the engine makes for longer than 0.35 s.
Byte 6 recomputed every frame.
Finish inside 2.3 s in states 1 and 3, 5.8 s in state 2, and in state 2 do not report clutch state 3 for more than 0.2 s.