DIY Datalogging Cable (Nokia FBUS Modification)
Technical guide to converting a legacy Nokia FBUS serial phone cable into a low-cost USB-to-TTL serial adapter for OBD1 Honda ECU datalogging.
Datalogging from an OBD1 Honda ECU requires converting the ECU's 5V TTL (Transistor-Transistor Logic) serial signal from the CN2 header into a standard USB signal.
A legacy Nokia FBUS mobile phone data cable (originally used for Nokia 3200/5100/6100 series phones) can be repurposed as a high-quality USB-to-TTL serial adapter, as these cables contain a Prolific PL-2303 transceiver chip.
Safety & Pinout
Caution
Pin 5 on the ECU's
CN2header carries raw +12V battery voltage. Never connect this pin to your USB adapter or laptop, as it will cause permanent damage to your equipment.
CN2 Header Pinout
| Pin | Function | Connection |
|---|---|---|
| 1 | Ground (GND) | Connect to Cable Ground |
| 2 | ECU Transmit (TX) | Connect to Cable Receive (RX) |
| 3 | +5V Logic | Do not connect |
| 4 | ECU Receive (RX) | Connect to Cable Transmit (TX) |
| 5 | +12V Power | DO NOT CONNECT |
Wiring Options
You must identify your specific Nokia cable type by opening the USB plug housing and examining the internal PCB.
Option A: RadioShack USB Cable (#170-0787)
- Brown: Ground (Pin 1)
- Orange: Cable RX -> Connect to Pin 2 (ECU TX)
- Red: Cable TX -> Connect to Pin 4 (ECU RX)
Option B: Generic / eBay Nokia Cable
- Black: Ground (Pin 1)
- White: Cable RX -> Connect to Pin 2 (ECU TX)
- Blue: Cable TX -> Connect to Pin 4 (ECU RX)
Software Configuration
- Jumper Removal: Desolder and remove the
J12jumper on the main ECU board to enable full-duplex communication. - Drivers: Install the generic Prolific PL-2303 USB-to-Serial driver.
- Baud Rate: Set your tuning suite (Crome, Hondata, TurboEdit) to the assigned COM port at 38400 baud.