P28-G03 ECU Technical Reference
Technical reference for the P28-G03 ECU, an OBDII unit found in 1996+ European Honda del Sol SOHC VTEC models.
The P28-G03 is an OBDII-compliant Engine Control Unit (ECU) utilized in 1996 and later European Honda del Sol models equipped with SOHC VTEC engines.
Note
The physical architecture and board layout of the P28-G03 closely resemble the P73 ECU series.
Specifications
- OBD Standard: OBDII
- Market: European (EU)
- Engine Compatibility: SOHC VTEC
- Chassis Compatibility: del Sol (EG)
Hardware Overview
The P28-G03 utilizes an OBDII-style connector and board architecture. When performing diagnostics or hardware modifications, ensure compatibility with the specific pinout requirements of the European OBDII harness.
Caution
While the board layout shares similarities with the P73, internal components and mapping may differ. Always verify specific component values before attempting cross-platform hardware swaps.
Diagnostic Resources
For further troubleshooting and sensor integration, refer to the following tools:
Resistor Color Code Reference
Use the color bands on through-hole resistors to identify their resistance value before installing ECU jumpers, pull-ups, voltage dividers, or sensor-scaling parts.
How to Read the Bands
| Resistor Type | Band 1 | Band 2 | Band 3 | Band 4 | Band 5 |
|---|---|---|---|---|---|
| 4-band | 1st digit | 2nd digit | Multiplier | Tolerance | - |
| 5-band | 1st digit | 2nd digit | 3rd digit | Multiplier | Tolerance |
Color Values
| Color | Digit | Multiplier | Tolerance |
|---|---|---|---|
| Black | 0 | x1 | - |
| Brown | 1 | x10 | +/- 1% |
| Red | 2 | x100 | +/- 2% |
| Orange | 3 | x1,000 | - |
| Yellow | 4 | x10,000 | - |
| Green | 5 | x100,000 | +/- 0.5% |
| Blue | 6 | x1,000,000 | +/- 0.25% |
| Violet | 7 | x10,000,000 | +/- 0.1% |
| Gray | 8 | x100,000,000 | +/- 0.05% |
| White | 9 | x1,000,000,000 | - |
| Gold | - | x0.1 | +/- 5% |
| Silver | - | x0.01 | +/- 10% |
| No band | - | - | +/- 20% |
Common ECU Examples
| Value | 4-Band Code | Typical Use |
|---|---|---|
| 220 ohm | Red, Red, Brown, Gold | LED/current-limiting or ECU hardware mods |
| 1k ohm | Brown, Black, Red, Gold | Pull-up, jumper, and driver-bias circuits |
| 1.2k ohm | Brown, Red, Red, Gold | Driver-bias circuits such as IACV repair references |
| 4.7k ohm | Yellow, Violet, Red, Gold | Transistor base resistor circuits |
| 10k ohm | Brown, Black, Orange, Gold | Pull-up, pull-down, and sensor-divider circuits |
Tip
Always confirm the measured value with a multimeter before soldering. Old ECU resistors can be heat-discolored, and some boards use small surface-mount parts marked with numeric codes instead of color bands.