Cars · Sensors

P39 ECU Technical Reference

Technical reference for the P39 OBD1 ECU used in 1992-1995 JDM Honda Prelude BB4 models equipped with the F22B DOHC non-VTEC engine.

Atualizado a 19 de junho de 2026 Intermédio 2

kabuki Author

carotman Author

The P39 ECU is an OBD1 engine control unit utilized in 1992â1995 JDM Honda Prelude BB4 vehicles equipped with the F22B DOHC non-VTEC engine.

ECU Overview

The P39 is typically found in automatic transmission configurations. Conversion to manual transmission operation requires specific hardware modifications to the PCB.

Important

When converting an automatic P39 ECU for manual transmission use, the resistor configuration must be updated. Specifically, the bridge at RP11 must be moved to RP12.

Component Documentation

The following images detail the internal PCB layout, resistor locations, and modification points for the P39 ECU.

P39 PCB Resistor Layout — Detail of resistor configuration on the P39 automatic ECU.

P39 Spoon Automatic ECU — Overview of the P39 Spoon automatic ECU.

P39 Resistor Detail — Secondary detail of resistor placement on the P39 automatic ECU.

Side profile view of the P39 Spoon automatic ECU.

Manual Conversion Point — Modification point for manual transmission conversion: RP11 to RP12.

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Technical Specifications

Feature	Specification
OBD Standard	OBD1
Market	JDM
Vehicle	Prelude BB4
Engine	F22B DOHC (Non-VTEC)
Transmission	Automatic (Stock)

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Model Prelude