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OBD1 ECU Chipping Wirelist
Pin connections and traces between the MCU, latch, and external EPROM socket on OBD1 Honda ECUs.
ROM Maps
Rom Maps An area to collaborate on all the memory addresses found in ROMs Rom Maps OBD1 Civic and Integra ECUs Memory Lo...
`27C256` EPROM Specifications
Technical specifications, pinout diagrams, equivalent part numbers, and speed requirements for the 27C256 EPROM chip use...
82C55 Programmable Peripheral Interface
Technical specifications and pinout mapping for the OKI MSM82C55A / Intel 82C55 Programmable Peripheral Interface (PPI)...
Adding IAB Control to an OBD1 P28 ECU
Hardware modification guide to add Intake Air Bypass (IAB) secondary runner controls to an OBD1 Honda P28 Civic ECU.
Automatic Accord OBD2-to-OBD1 ECU and TCU conversion
Wiring conversion guide and pinout translation tables to run an automatic OBD2a Accord using an automatic OBD1 Integra E...
Beginner's Honda ECU FAQ
Archived beginner answers for identifying, selecting, and researching Honda ECUs.
Chipping 1988-1989 OBD0 ECUs
Archived socketing and chipping methods for early 1988-1989 Honda and Acura OBD0 ECUs.
Chipping OBD2 Honda ECUs (OKI `66507` / `66P507`)
Hardware guide for chipping OBD2 Honda ECUs by replacing the OKI 66507 processor with a programmed 66P507 OTP microcontr...
Chipping the JDM OBD1 P30 ECU
Hardware modification guide for socketing, chipping, and converting JDM square-case OBD1 P30 ECUs to manual transmission...
Chipping the OBD0 PM6 ECU (1988–1991 Civic/CRX Si)
Step-by-step hardware guide to chipping the OBD0 PM6 ECU (1988–1991 Civic/CRX Si) to accept external EPROMs and custom t...
Crome JavaScript scripting API
Reference for the legacy Crome ROM editor JavaScript API used by scripts, ROM handlers, and plug-ins.
DIY Datalogging Cable via 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...
DIY Easy-RTP v1.0 build and installation guide
Archived assembly guide and partial OBD0/OBD1 installation notes for the DIY Easy-RTP v1.0 board.
DIY Engine Simulator for ECU Bench Testing
A detailed build guide for a DIY hardware Engine Simulator (ECU Stimulator) used to bench-test and debug Honda OBD0, OBD...
Easy-RTP v1.0 OBD1 installation
Preliminary archived installation procedure for connecting Easy-RTP v1.0 to OBD1 ECUs.
Guide to Bulb-Style Desoldering Irons
Guide to using and modifying budget-friendly bulb-style desoldering irons for ECU chipping and through-hole solder remov...
Honda ECU component sourcing reference
Historic supplier part numbers for components used when socketing, modifying, or repairing Honda OBD0 and OBD1 ECUs.
Honda ECU Serial Datalogging (`CN2` TTL Header)
Learn how Honda OBD1 ECUs communicate with tuning laptops via serial TTL signals (CN2 header), including pinouts, settin...
Honda OBD Generations Guide (OBD0, OBD1, OBD2a, OBD2b)
An overview of Honda On-Board Diagnostics generations (OBD0, OBD1, OBD2a, OBD2b). Learn their differences, connector lay...
Honda PR3 ECU Reference Guide
Hardware and software reference guide for the OBD0 and OBD1 PR3 DOHC VTEC ECU used in B16A-equipped Integra and Civic mo...
How to Install the "Add Extra Features" Plugin in Crome
Software guide for downloading, installing, and applying the Add Extra Features plugin in the Crome OBD1 ROM editor to e...
JDM P30 D12 analog-input modification
Archived JDM P30 D12 circuit modification for logging a 0-5 V analog input through the ECU.
Knock Sensor
A piezo sensor that lets the ECU hear detonation and pull timing to protect the engine.
Logging an external 0-5 V sensor through P30 D12
Archived USDM P30 D12 analog-input method for logging an external 0-5 V sensor.
OBD0 inter-chip communication notes
Reverse-engineered notes on the OBD0 ECU memory bus, peripheral address ranges, and chip-select logic.
OBD1 8-bit MAP calibration in millibars
Archived P72/P75 OBD1 MAP-byte formulas and calibration values for stock and uncorked ROM code.
OBD1 Honda P28 ECU Reference Guide
A hardware and software reference guide for the USDM and EDM OBD1 P28 SOHC VTEC ECU (from D16Z6 engines), the most popul...
OBD1 Honda P72 ECU Reference Guide
A comprehensive hardware and software reference guide for the OBD1 P72 Integra GS-R DOHC VTEC ECU, including RAM and ROM...
OBD1 PR4 ECU Hardware & Reference
Hardware layouts, component locations, and chipping instructions for the OBD1 Acura Integra PR4 ECU.
OBD1 Prelude P14 ECU Guide (H23A)
Hardware specifications, board layout differences, knock sensor configurations, and ROM files for the 1993–1995 OBD1 Pre...
OKI M6260A Engine Control Counter IC
Technical reference for the OKI M6260A Engine Control Counter IC, a custom timing and I/O coprocessor used in Honda OBD0...
Soldering Iron Selection & Guidelines
How to select and use a soldering iron for ECU modification, covering wattages, tip shapes, and temperature settings.
Throttle Position Sensor (TPS)
How the Throttle Position Sensor (TPS) works, how to calibrate/adjust it, and troubleshooting common TPS issues.
UberData tuning FAQ
Archived setup and tuning FAQ for the legacy UberData OBD1 Honda ROM editor.
USB-to-Serial TTL Adapters (`FTDI` / USBMOD3)
Technical guide to wiring, configuring, and loopback testing FTDI-based USB-to-TTL serial adapters for Honda ECU datalog...
Wideband Installation Guide for Honda OBD1 ECUs
Learn how to install and configure an AEM wideband O2 sensor on your Honda OBD1 ECU using Honda Tuning Suite (HTS) or Ho...
Willem EPROM Programmer Guide
Configuring and using Willem EPROM programmers (parallel/LPT port) for burning SST 27SF512 and 27SF256 ROM chips for Hon...
Wire Harness
Compare Honda OBD0, OBD1, OBD2A, and OBD2B ECU wire-harness connectors and pinout layouts.
Fuel Injector Offsets Database
A comprehensive database of battery offset (dead time/latency) tables for OEM and aftermarket fuel injectors.
`27SF256`
This is supposed to be an electricallyerasable replacement for 27 C256. SST Datasheet (PDF) These can be purchased dirt...
`28C256` EEPROM Pinout & Compatibility
Technical specifications, pinout mapping, and socket modification instructions for using the 28C256 EEPROM chip in stand...
`29C256`
the ATMEL AT29C256 chip is the de facto FLASHROM chip in use. It uses a 5V programming voltage, can be erased repeatedly...
`66207`
The Oki 66207 MCU is used mainly in the OBD1 Civic Integra ECUs. It uses the NX8/200 core. Lots of useful documentation...
`74HC373`
The 74HC373 is an octal Latch chip. It Latches 8 bits of data, and is usally used when adding an external rom to a MCU
`C144`
C144 is a NPN switching transistor. It has been successfully replaced with C2785 (and its replacements).
`MAX233`
the Maxim MAX233 chip is commonly used to translate between TTL and RS232 levels during serial communication.
02D011F0-1500
to convert nonvtec "11F0" boards from nonvtec to VTEC, add: In top left quadrant: C60 1uF, 35v electrolytic (tantalum?)...
02D01720-1500
To convert a "1720" board from nonvtec to VTEC add the following parts: Required: Q26: C2785 (note: I used a C144 and it...
02D01980-1500
Editor's note: the small list does not appear to have the required parts for the IABsAuthor: eg6ajk Date: 052403 15:10 m...
203 AC
Author: PRCIVIC Date: 052803 21:46 Ok I have commented the AC routine posted for the benefits of those with no assembly...
5050s
Use this method if you install a 5050s in IC14 and you get a MIL code 21. STEP 1 modify and install the VTEC parts as no...
5128XRAM
5128 XRAM explanation : The 5128 chip present in OBD0 ECUs is a 2K byte(?) SRAM chip. It is mapped into memory space at...
515X High Side Switch
Honda uses a 5 pin high side switch in a lot of their OBD1 and OBD2 ECUs to control solenoids like auto trans and VTEC s...
66k Assembler Docs
Here you can find all the documentation on the Oki 66K achitecture that we have been able to find. If it isn't attached...
66k Resources
Documentation 66k Assembler Docs factory documentation on the Oki 66xxx processors used in most OBD1 and OBD2 implemenat...
91PM6 Target Idle
Author: xtensive Date: 010403 20:47 Ok, here's what I found: That whole area is data tables. The routine that calls the...
A143
Thanks again Javier (dohcvtec): A143====Panasonic NTE2362 === (Digikey 2SB1030ARACTND) (do not be fooled into believing...
A5
A5h (opcode 'A5' in hexidecimal) is the "reserved" opcode of the 8051 instruction set. This means it is NOT a valid inst...
Acura Integra PR4 OBD0 ECU Pinouts and Wiring
Wiring layout, pinout details, and schematic analysis for the OBD0 and OBD1 Acura Integra PR4 ECU.
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