CAN AC and CEL for MSV70

[Striker01]

I started trying to figure out CAN stuff to get the ECU to control AC and a CEL.

I will probably use the wrong terminology or put out some bad info, bear with me. Posting here because I know some of you are probably good at this stuff.

It looks like MSV70 uses the e46 CAN addresses(ARBIDs?), some of which are fairly well documented. It also has two that aren't listed in the e46 stuff, maybe for valvetronic.

https://www.bimmerforums.com/forum/showthread.php?1887229-E46-Can-bus-project#:~:text=Hello.%20There%20has%20been%20much ,creating%20a%20Can%20Bus%20solution

Here is what I see with Savvycan and just the ECU and EKP on the CAN network.



I have verified that 0x00545 byte 0 is for the CEL, bit 1 is emissions light and 4 is EML. So by monitoring for HEX 10, 02, or 12 on byte 0 we should be able to power on a CEL. Byte 3 bit 3 (08 HEX) is supposed to be an overheat indication, I need to hook up a variable resistor to test that one.

I have an arduino and sketch written to monitor the bus but can't get it to work. It is wired according to the arduino documentation. I have some hardware hoveringuy recommended on the way to try.

The sketch is written to turn off the LED when those messages are present, just to verify the board is actually working. The LED comes on with power up but I'm still trying to figure out if its actually listening to the bus. If any of you guys are familiar will you look over my sketch and make sure it is correct, I used AI to write it.

#include <Arduino_CAN.h>
const int LED_PIN = 3;
void setup() {
pinMode(LED_PIN, OUTPUT);
digitalWrite(LED_PIN, HIGH); // LED starts ON
Serial.begin(115200);
delay(200);
Serial.println("CAN LED control - UNO R4 Minima");
if (!CAN.begin(CanBitRate:: BR_500k)) {
Serial.println("Starting CAN failed!");
while (1);
}
Serial.println("CAN initialized @ 500 kbps");
}
void loop() {
// Check if a new message is available
if (CAN.available()) {
CanMsg const &msg = CAN.read();
// We only care about ID 0x545 (1349 decimal)
if (msg.id == 0x545 && msg.data_length >= 4) {
uint8_t b0 = msg.data[0];
uint8_t b3 = msg.data[3];
// Condition for TURNING LED OFF
bool shouldBeOff = (b3 == 0x08) &&
(b0 == 0x02 || b0 == 0x10 || b0 == 0x12);
if (shouldBeOff) {
digitalWrite(LED_PIN, LOW);
// Optional: debug
// Serial.printf("OFF - %02X %02X\n", b0, b3);
} else {
digitalWrite(LED_PIN, HIGH);
// Serial.printf("ON - %02X %02X\n", b0, b3);
}
}
// Any other message ID or too short message → LED stays ON
}
// Small delay is recommended when using CAN.read() in a tight loop
delay(5);
}



For the AC I managed to isolate the bit that signals the "aircon input request" in INPA, idle jumps up when it happens so that is a positive sign! 0x00615 byte 0 Hex 80 from the above link doesn't work for me.



I used the Savvycan send frame function to try every HEX combination on 0x00615 byte 0 to figure out which bit signals the ECU. Bit 7 @ 1 turns it on. Here is the table:

AC INPUT ON		AC INPUT OFF
HEX	BINARY	BINARY	HEX
	_1________	_0________
40	01000000	00000000	00
41	01000001	00000001	01
42	01000010	00000010	02
43	01000011	00000011	03
44	01000100	00000100	04
45	01000101	00000101	05
46	01000110	00000110	06
47	01000111	00000111	07
48	01001000	00001000	08
49	01001001	00001001	09
4A	01001010	00001010	0A
4B	01001011	00001011	0B
4C	01001100	00001100	0C
4D	01001101	00001101	0D
4E	01001110	00001110	0E
4F	01001111	00001111	0F
50	01010000	00010000	10
51	01010001	00010001	11
52	01010010	00010010	12
53	01010011	00010011	13
54	01010100	00010100	14
55	01010101	00010101	15
56	01010110	00010110	16
57	01010111	00010111	17
58	01011000	00011000	18
59	01011001	00011001	19
5A	01011010	00011010	1A
5B	01011011	00011011	1B
5C	01011100	00011100	1C
5D	01011101	00011101	1D
5E	01011110	00011110	1E
5F	01011111	00011111	1F
60	01100000	00100000	20
61	01100001	00100001	21
62	01100010	00100010	22
63	01100011	00100011	23
64	01100100	00100100	24
65	01100101	00100101	25
66	01100110	00100110	26
67	01100111	00100111	27
68	01101000	00101000	28
69	01101001	00101001	29
6A	01101010	00101010	2A
6B	01101011	00101011	2B
6C	01101100	00101100	2C
6D	01101101	00101101	2D
6E	01101110	00101110	2E
6F	01101111	00101111	2F
70	01110000	00110000	30
71	01110001	00110001	31
72	01110010	00110010	32
73	01110011	00110011	33
74	01110100	00110100	34
75	01110101	00110101	35
76	01110110	00110110	36
77	01110111	00110111	37
78	01111000	00111000	38
79	01111001	00111001	39
7A	01111010	00111010	3A
7B	01111011	00111011	3B
7C	01111100	00111100	3C
7D	01111101	00111101	3D
7E	01111110	00111110	3E
7F	01111111	00111111	3F
C0	11000000	10000000	80
C1	11000001	10000001	81
C2	11000010	10000010	82
C3	11000011	10000011	83
C4	11000100	10000100	84
C5	11000101	10000101	85
C6	11000110	10000110	86
C7	11000111	10000111	87
C8	11001000	10001000	88
C9	11001001	10001001	89
CA	11001010	10001010	8A
CB	11001011	10001011	8B
CC	11001100	10001100	8C
CD	11001101	10001101	8D
CE	11001110	10001110	8E
CF	11001111	10001111	8F
D0	11010000	10010000	90
D1	11010001	10010001	91
D2	11010010	10010010	92
D3	11010011	10010011	93
D4	11010100	10010100	94
D5	11010101	10010101	95
D6	11010110	10010110	96
D7	11010111	10010111	97
D8	11011000	10011000	98
D9	11011001	10011001	99
DA	11011010	10011010	9A
DB	11011011	10011011	9B
DC	11011100	10011100	9C
DD	11011101	10011101	9D
DE	11011110	10011110	9E
DF	11011111	10011111	9F
E0	11100000	10100000	A0
E1	11100001	10100001	A1
E2	11100010	10100010	A2
E3	11100011	10100011	A3
E4	11100100	10100100	A4
E5	11100101	10100101	A5
E6	11100110	10100110	A6
E7	11100111	10100111	A7
E8	11101000	10101000	A8
E9	11101001	10101001	A9
EA	11101010	10101010	AA
EB	11101011	10101011	AB
EC	11101100	10101100	AC
ED	11101101	10101101	AD
EE	11101110	10101110	AE
EF	11101111	10101111	AF
F0	11110000	10110000	B0
F1	11110001	10110001	B1
F2	11110010	10110010	B2
F3	11110011	10110011	B3
F4	11110100	10110100	B4
F5	11110101	10110101	B5
F6	11110110	10110110	B6
F7	11110111	10110111	B7
F8	11111000	10111000	B8
F9	11111001	10111001	B9
FA	11111010	10111010	BA
FB	11111011	10111011	BB
FC	11111100	10111100	BC
FD	11111101	10111101	BD
FE	11111110	10111110	BE
FF	11111111	10111111	BF

Still a long way to go but its a start! Any help would be appreciated!

[hoveringuy]

I'm glad all of that data is already public knowledge because doing bitwise comparisons is a major PITA! Good work!

[nando]

you can also set MSV70 to use BN2000 - not sure if that's already been figured out yet though.

[Striker01]

I'm glad all of that data is already public knowledge because doing bitwise comparisons is a major PITA! Good work!

And I’d have no idea where to start. I just found the MS43 wiki, it has even more data but found some that don’t match what I’m seeing with MSV70. I don’t think it will apply for this project. Just a bit listed as unused that changes when I activate the compressor in INPA on 0x316. I don’t foresee messing with DME produced data, just isolating what changed with it on.

[Striker01]

you can also set MSV70 to use BN2000 - not sure if that's already been figured out yet though.

Welcome back Nando.

Just read a little on that. Not sure if it would be any benefit. Have to change my EKP.

Is that what Hoveringuy is running since his is set to e90 now?

[Striker01]

I had a chance to test some of the AC stuff today. I can confirm that x60002 pin 21 is normally high and goes low to cycle on compressor and that once the DME receives the AC on message it keeps the compressor on until a message is received to turn it off. I tested this by stopping the transmission of 0x615 and the compressor stayed engaged. My compressor is an LED for now as my AC isn't plumbed yet.

The DME keeps the compressor engaged during high RPMs and under full throttle acceleration. I'm assuming turning it off during those conditions is done by the instrument cluster and will have to be added to the arduino code.

I played around with sending a couple different combinations of messages on 0x615 while driving.

Here is that message info from the wiki site:

CAN Arbitration ID for ICL3 is 0x615. I only sent 4 bytes during testing today.

Its sent out by the instrument cluster at a refresh rate of 200ms

• Byte 0 - Bitfield =
• The compressor comes on and stays on with only this byte transmitting. The idle bump changes by adjusting the value of the first 5 bits. With the biggest bump at DF as would be expected.
  • Bit 0 - TQ_ACCIN_CAN [0]
  • Bit 1 - TQ_ACCIN_CAN [1]
  • Bit 2 - TQ_ACCIN_CAN [2]
  • Bit 3 - TQ_ACCIN_CAN [3]
  • Bit 4 - TQ_ACCIN_CAN [4]
    • Torque Offset For Air Conditioning Compressor 0-31nm.
  • Bit 5 - LV_REQ_TCO_L Request For Lowering Cooling Temp (c_tco_bol_ect). With it off my car stayed around 100C, when I turned it on the car immediately went to the 80C target. I also noticed something else strange here: With the tune I have the coolant temps vary greatly from 80 all the way to the hot ECO mode, depending on how I'm driving the car. With the AC engaged it didn't fluctuate at all, regardless of how hard I was driving it.
  • Bit 6 - LV_ACCIN Air Conditioning Compressor Status (0=off, 1=on)
  • Bit 7 - LV_ACIN Air Conditioning Request (0=off, 1=on)

Byte 1 - Bitfield = 00AC will operate just like the stock e30, fan on with AC. If I can figure out how the last 4 bits adjust the fan speed I my re-visit later.

• • Bit 0 - LV_REQ_HEAT Increased Heat Request
  • Bit 1 - LV_TOW Trailer Operation Mode
  • Bit 2 - LV_LGT Day / Night Lighting
  • Bit 3 - LV_HS Hood Switch
  • Bit 4 - N_ECF [0]
  • Bit 5 - N_ECF [1]
  • Bit 6 - N_ECF [2]
  • Bit 7 - N_ECF [3] Electric Cooling Fan Level
• Byte 2 - Bitfield = 40 or 00
  • Bit 0 - [0]
  • Bit 1 - [1]
  • Bit 2 - [2]
  • Bit 3 - [3]
  • Bit 4 - [4]
  • Bit 5 - [5]
  • Bit 6 - Request Raised Idle - Turning this on or off doesn't seem to affect idle speed, only byte 0. Will check again when my AC system is plumbed and charged.
  • Bit 7 - unused
• Byte 3 - TAM_CAN Ambient Temperature = 1E = 30C this at 00 doesn't affect compressor status or idle
• I didn't transmit anymore than 4 bytes.
• Byte 4 - Bitfield =
  • Bit 0 - LV_DOOR Door Switch
  • Bit 1 - LV_HBR Hand Brake Switch
  • Bit 2 - LV_SUSP [0]
  • Bit 3 - LV_SUSP [1] Suspension Switch
  • Bit 4 -
  • Bit 5 - LV_REQ_TCO_L -
  • Bit 6 - LV_ACCIN Air Conditioning Compressor Status (0=off, 1=on)
  • Bit 7 - LV_ACIN Air Conditioning Request (0=off, 1=on)
• Byte 5 - Bitfield
  • Bit 0 -
  • Bit 1 -
  • Bit 2 -
  • Bit 3 -
  • Bit 4 -
  • Bit 5 -
  • Bit 6 - VSS_DIS [0]
  • Bit 7 - VSS_DIS [1]
• Byte 6 - VSS_DIS [2-9] Displayed Vehicle Speed
• Byte 7 -