Hi guys,
Check out the below I copy/pasted from Grok. Arduino's are a bit outside of my swimlane, so I'm posting this here to see if it's wrong, hopefully it's not, but I'm sure there are errors. I can't trust AI fully yet. Especially since I saw a lot of the references it's pulling from are my.is and other forums. And then I asked it to draw me pictures based on the question lol, the pictures aren't laid out like typical wire diagrams, and are mostly not labeled, so I'd spend more time trying to decipher it than I would drawing my own diagram. Let me know what you think!
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Question
"how do I connect an mcp2515 with an arduino to a 2002 IS300. What is the BEAN code needed for the arduino. And what pins do I connect each wire to on the arduino, mcp2515 and IS300"
Answer:
Overview
The 2002 Lexus IS300 (JCE10 chassis) does not use a standard CAN bus for OBD-II diagnostics—it uses the ISO 9141-2 protocol (K-Line on pin 7 of the OBD-II port). However, the vehicle employs Toyota's BEAN (Body Electronics Area Network, also called MPX) protocol for multiplex communication to the instrument cluster and body ECUs. This is a single-wire, 12V serial bus (not differential like CAN).
The MCP2515 is a CAN controller, so it won't directly interface with the IS300's OBD-II or BEAN bus. A common setup for custom projects (e.g., engine swaps or gauge hacking) is to use the MCP2515 to read CAN data from an aftermarket ECU or adapter, then convert it to BEAN messages via Arduino to drive the OEM instrument cluster. This requires the BeanMPX Arduino library for BEAN handling and a CAN library (e.g., arduino-CAN by Sandeep Mistry) for MCP2515.
Warnings:
1. Arduino to MCP2515 (Standard SPI Interface)
Use these for the Arduino to communicate with the MCP2515. Assumes Arduino Uno pins.
2. MCP2515 to 2002 IS300 (CAN Side)
Since the stock IS300 lacks full CAN, this assumes you're connecting to an external CAN source (e.g., aftermarket ECU like ECUMaster or AEM) or using an OBD-II-to-CAN adapter (e.g., for PIDs via ISO-to-CAN bridge). If tapping stock wiring:
For stock OBD-II access (non-CAN):
BEAN uses a single MPX wire (12V idle, pulls low for data at ~1.2kbps). Tap the MPX line to the combination meter (instrument cluster). From the 2002 IS300 wiring diagram (EWD451U):
Circuit Note: The BeanMPX library expects software serial. Use a bidirectional level shifter like TXS0108E or a simple resistor divider for RX (12V to 5V) and transistor for TX (5V to 12V pull-down). Reference the library's circuit diagram: BeanMPX/bean-mpx_circuit.png at master · fiztech-code/BeanMPX.
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4. IS300 OBD-II Port (If Using for Reference/Diagnostics)
For completeness (non-CAN):
Install the BeanMPX library in Arduino IDE. This example initializes BEAN, sets an ACK for cluster messages, receives CAN data (e.g., engine temp from MCP2515), and sends a sample BEAN message to the cluster (e.g., for coolant temp). Replace engTemp array with sniffed bytes for your needs (e.g., from logic analyzer on MPX wire). Specific IS300 cluster messages aren't publicly listed, but examples include:
How the Code Works:
![Image]()
![Image]()
Check out the below I copy/pasted from Grok. Arduino's are a bit outside of my swimlane, so I'm posting this here to see if it's wrong, hopefully it's not, but I'm sure there are errors. I can't trust AI fully yet. Especially since I saw a lot of the references it's pulling from are my.is and other forums. And then I asked it to draw me pictures based on the question lol, the pictures aren't laid out like typical wire diagrams, and are mostly not labeled, so I'd spend more time trying to decipher it than I would drawing my own diagram. Let me know what you think!
-------------
Question
"how do I connect an mcp2515 with an arduino to a 2002 IS300. What is the BEAN code needed for the arduino. And what pins do I connect each wire to on the arduino, mcp2515 and IS300"
Answer:
Overview
The 2002 Lexus IS300 (JCE10 chassis) does not use a standard CAN bus for OBD-II diagnostics—it uses the ISO 9141-2 protocol (K-Line on pin 7 of the OBD-II port). However, the vehicle employs Toyota's BEAN (Body Electronics Area Network, also called MPX) protocol for multiplex communication to the instrument cluster and body ECUs. This is a single-wire, 12V serial bus (not differential like CAN).
The MCP2515 is a CAN controller, so it won't directly interface with the IS300's OBD-II or BEAN bus. A common setup for custom projects (e.g., engine swaps or gauge hacking) is to use the MCP2515 to read CAN data from an aftermarket ECU or adapter, then convert it to BEAN messages via Arduino to drive the OEM instrument cluster. This requires the BeanMPX Arduino library for BEAN handling and a CAN library (e.g., arduino-CAN by Sandeep Mistry) for MCP2515.
Warnings:
- Tapping wires can damage the car if done incorrectly—use a wiring diagram and multimeter to verify.
- BEAN is 12V; use a level shifter (e.g., optocoupler or MOSFET-based) to protect the Arduino's 5V pins.
- Specific BEAN message bytes (e.g., for RPM, temp) must be reverse-engineered or sniffed using a logic analyzer, as they vary by model. Common resources include Toyota service manuals or forums like ClubLexus.
- Arduino Uno/Nano (or similar).
- MCP2515 CAN module.
- BeanMPX library (download from GitHub: fiztech-code/BeanMPX).
- arduino-CAN library (install via Arduino IDE Library Manager).
- Level shifter for BEAN (12V to 5V).
- OBD-II cable or direct wire taps.
1. Arduino to MCP2515 (Standard SPI Interface)
Use these for the Arduino to communicate with the MCP2515. Assumes Arduino Uno pins.
| MCP2515 Pin | Arduino Pin | Description |
|---|---|---|
| VCC | 5V | Power (5V) |
| GND | GND | Ground |
| CS | 10 | Chip Select (SPI) |
| SO (MISO) | 12 | SPI Data Out |
| SI (MOSI) | 11 | SPI Data In |
| SCK | 13 | SPI Clock |
| INT | 2 | Interrupt (optional, for RX notifications) |
Since the stock IS300 lacks full CAN, this assumes you're connecting to an external CAN source (e.g., aftermarket ECU like ECUMaster or AEM) or using an OBD-II-to-CAN adapter (e.g., for PIDs via ISO-to-CAN bridge). If tapping stock wiring:
- Connect MCP2515 CAN-H to CAN High wire (if available, e.g., via OBD-II pin 6—though not active on stock ISO setup).
- Connect MCP2515 CAN-L to CAN Low wire (OBD-II pin 14).
- Add 120Ω termination resistor across CAN-H and CAN-L if the bus requires it (measure resistance on the car's harness; stock may be ~60Ω).
For stock OBD-II access (non-CAN):
- Use a K-Line interface instead of MCP2515 for diagnostics. But if forcing CAN, tap engine ECU harness wires (from wiring diagram: check J7 junction for potential CAN-like signals, but confirm with multimeter).
BEAN uses a single MPX wire (12V idle, pulls low for data at ~1.2kbps). Tap the MPX line to the combination meter (instrument cluster). From the 2002 IS300 wiring diagram (EWD451U):
- Location: Instrument cluster connectors C9 or C10 (behind dash). Look for MPX1/MPX2 lines in the harness.
- Wire Colors: Light Yellow (L-Y) or Red-Yellow (R-Y) tracer for MPX+ (signal). Ground is Black (B).
- Connector Pins: On combination meter connector IA3 (or IH1): Pin for MPX is typically IA3-1 or similar (verify with diagram; MPX connects via J16/J17 junctions).
- Connections:
- Arduino pin 8 (RX) → Level shifter input (5V side) → MPX signal wire (L-Y/R-Y, tapped in parallel).
- Arduino pin 9 (TX) → Level shifter output (12V side) → Same MPX signal wire.
- Arduino GND → Chassis ground (e.g., OBD-II pin 4/5).
- Power the level shifter from car's 12V (ignition-switched, e.g., white-red wire W-R).
Circuit Note: The BeanMPX library expects software serial. Use a bidirectional level shifter like TXS0108E or a simple resistor divider for RX (12V to 5V) and transistor for TX (5V to 12V pull-down). Reference the library's circuit diagram: BeanMPX/bean-mpx_circuit.png at master · fiztech-code/BeanMPX.
4. IS300 OBD-II Port (If Using for Reference/Diagnostics)
For completeness (non-CAN):
- Pin 16: +12V battery.
- Pin 4/5: Ground.
- Pin 7: K-Line (ISO 9141 for diagnostics—not for MCP2515).
Install the BeanMPX library in Arduino IDE. This example initializes BEAN, sets an ACK for cluster messages, receives CAN data (e.g., engine temp from MCP2515), and sends a sample BEAN message to the cluster (e.g., for coolant temp). Replace engTemp array with sniffed bytes for your needs (e.g., from logic analyzer on MPX wire). Specific IS300 cluster messages aren't publicly listed, but examples include:
- Coolant temp: Destination ID 0x10, data like {0x01, 0x02, temp_value}.
- RPM: Similar format; sniff during driving.
Code:
#include <BeanMPX.h> // BeanMPX library
#include <CAN.h> // arduino-CAN library for MCP2515
#include <SPI.h>
// BEAN pins (software serial)
#define BEAN_RX 8
#define BEAN_TX 9
// Sample BEAN message for engine temp (replace with actual sniffed bytes)
uint8_t engTemp[] = {0x10, 0x01, 0x80, 0x50}; // Example: Dest ID 0x10, Msg ID 0x01, data 0x80 0x50 (adjust for temp)
BeanMPX bean; // BEAN object
void setup() {
Serial.begin(9600); // For debugging
// Initialize MCP2515 CAN at 500kbps (common for automotive)
if (!CAN.begin(500E3)) {
Serial.println("CAN init failed!");
while (1);
}
CAN.setPins(10, 2); // CS pin 10, INT pin 2 (matches wiring)
// Initialize BEAN: ACK messages, then RX/TX pins, timer (0 = timer1)
bean.ackMsg((const uint8_t[]){0xFE}, 1); // ACK for 0xFE dest ID (common for cluster)
bean.begin(BEAN_RX, BEAN_TX, 0);
Serial.println("Setup complete: CAN + BEAN ready.");
}
void loop() {
// Read CAN message (e.g., from ECU, assume ID 0x7E0 for engine data)
int packetSize = CAN.parsePacket();
if (packetSize) {
long canID = CAN.packetId();
if (canID == 0x7E0) { // Example: Engine PID response ID
uint8_t buffer[8];
int len = CAN.readBytes(buffer, packetSize);
// Process CAN data (e.g., extract temp from bytes 3-4, scale to BEAN format)
uint8_t temp = buffer[3]; // Placeholder: actual parsing needed
engTemp[3] = temp; // Update BEAN message with temp value
// Send to BEAN cluster (repeats 3x if no ACK)
bean.sendMsg(engTemp, sizeof(engTemp));
Serial.print("Sent BEAN temp: "); Serial.println(temp);
}
}
// Optional: Read incoming BEAN messages (e.g., for ACKs or queries)
uint8_t msgBuffer[32];
int msgLen = bean.readMsg(msgBuffer); // Copies frame to buffer
if (msgLen > 0) {
Serial.print("Received BEAN msg len: "); Serial.println(msgLen);
// Parse buffer: [len, type (R/T), frame data...]
}
delay(100); // Adjust for bus timing
}- CAN Receive: Listens for packets on the bus. Parse PIDs (e.g., 0x05 for coolant temp) using OBD2 requests if needed (add OBD library).
- BEAN Send: sendMsg transmits the frame. Messages are ~12V serial; library handles timing/parity.
- Testing: Upload, monitor Serial for debug. Use a scope on MPX wire to verify signals. Start with known messages (e.g., dummy temp = 80°C).
- Customization: Sniff BEAN with Arduino + logic analyzer (Saleae or similar) while stock ECU runs. Common tools: sigrok or Arduino sketch for capture.
- Download the full 2002 IS300 wiring diagram (EWD451U) from 2jzgarage.com for exact cluster pins.
- For specific BEAN messages, check ClubLexus forums or reverse-engineer via sniffing (drive the car, log MPX data).
- If this is for an engine swap, reference the YouTube video "BeanMPX interface with CAN-BUS" for IS300-specific setup.
- Test on bench first: Power cluster with 12V, send dummy messages.
.
