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ROM addresses and their functions specific to the stock Honda P72 used in:

  • 94-95 OBD1 Integra GSR (1.8L B18C? DOHC Vtec)
  • 96-00 OBD2 Integra GSR

Picture of OBD1 P72 (thanks Katman): scan

To add an address, click Edit below, find where your Hex Offset address is, and then add your new entry like so:

"|''location''|''length in bytes''|''description''|''notes''|"

Note: Please do not add info specific to specialized ROMs such as Uber P72 and Hi Res P72.


Location Bytes Description Notes
00bb 1 raw MAP set at 0844
00bf 1 adjusted MAP more info...
00C3 1 Current RPM also copied to 236h (look at 0816h)
00C4 2 Current RPM
00CC 1 VSS Sensor km/h
00D1 1 Current TPS Throttle Position (see Tps Sensor)
00D4 1 TP Sensor
00D5 1 TPS Delta
00D7 1 Input into ADCR5 not connected to a sensor on USDM P72
00D8 1 IAT Sensor
00D9 1 ECT Sensor  
00DA 1 O2 Sensor
011a 1 CEL byte 1
011b 1 CEL byte 2
011c 1 CEL byte 3
011d 1 CEL byte 4
011E.3 1b Auto/Manual config bit
0127.1 1b VTEC bit
0131.0 1b set if speed > 15 kph, cleared if speed < 10 kph used to determine if VTEC should be on
0131.1 1b set when RPM is above VTEC switchover RPM has hysteresis, related to VTEC logic
0131.2 1b set when RPM is above some level has hysteresis, related to VTEC logic
0131.6 1b similar to 0131.2, but at a different level not related to VTEC logic
0131.7 1b similar to 0131.6, but looks at MAP, not RPM not related to VTEC logic
0192   Rev cut limit
0194   Rev resume limit
01D2 1 Column of Fuel/Ignition Map
01D8 1 Low Cam Row
01D9 1 High Cam Row
0210.3 1b Power Steering Pressure(PSP) switch input If pin B8 (PSP) is grounded, 0x0210.3 will read 0 else it will read 1
0211.2 1b AC switch more info...
0212.2 1b Indicates MAP problem
0212.4 1b Indicates other MAP problem
0212.6 1b Indicates TPS problem
0216.4 1b Vtec Enable Flag
0216.6 1b Holds 02 Sensor Heater Enable Flag
0219.3 1b ?????????
0227.4 1b PA Sensor Enable Flag
0227.6 1b Knock Sensor Enable Flag
022d.1 1b VTEC VSS Check Enable Flag
0236 1 Current RPM in 8bit form (IAB Control @ 4393h routine)
0244 1 Knock Retard
0246 1 Ignition Advance
0257 1 controls ADC MUX Channel 0 thru 7
025A 2 Current target idle RPM function of ECT and tbl_5ba7
0356.1 1b Serial comm mode 1 for 9470 UART mode, 0 for 62500 9-bit mode
03A0 2 Injector Duration
03CD 1 BARO Sensor
03D2 1 ELD? (ADC input 1)
0f00 1 82C55 Port A inputs
1f00 1 82C55 Port B outputs
2f00 1 82C55 Port C outputs
3f00 1 82C55 Command Register
4700 1 memory-mapped digital inputs bit values modified and copied to 0119 and 0211, includes feedback from A/C switch, VTEC solenoids and others
P0.0 1b A/C Clutch Output
P0.1 1b Purge Canister Output
P0.5 1b IAB Output previously thought to be P4.3
P1.0 1b Left VTEC Transistor Output (IC14)
P1.1 1b Right VTEC Transistor Output (IC13)
*Some of these addresses were determined by comparing dasms of 273 vs. 203 and correlating known 203 addresses with the ones found in the 273.


Location Bytes Description Notes
0630 3 Injector test bypass #1 Disable J label_063D(checked)03 3D 06
0B85 2 Low Speed Ignition Map Config, Column Size more info...
0B87 2 Low Speed Ignition Map Config, Row Size more info...
0B95 3 Low Speed Ignition Map at this jump more info...
0BA1 2 High Speed Ignition Map Config, Row Size more info...
0BA9 2 High Speed Ignition Map at this jump more info...
11BA 1 VTEC On/Off Logic
120E 1 VTEC Coolant Temp Check (enable=44/disable=FF)
1520 3 Injector test bypass #2 Disable J label_153A(ckecked)03 3A 15
2315 3 O2 Heater Jump Routine Change to "03 50 23" to disable O2 heater
2D43 2 Rolling Target Idle RPM = 1875000/(word at 0x2D43)
2D58 2 Cold Target Idle RPM = 1875000/(word at 0x2D58)
2D81 2 Warm Target Idle RPM = 1875000/(word at 0x2D81)
3BE1 3 VTP Sensor Disable Change to "03 FF 3B" to disable VTP sensor check (tested!)
43A2 1 IAB on IAB open 8bit RPM (byte at 0x43A2)
439D 1 IAB off IAB close 8bit RPM (byte at 0x439D)
5466 1 Vtec Enable (enable=FF/disable=00)(Needs Testing?)
5467 1 Knock Sensor (enable=FF/disable=00)
5468 1 O2 Heater (enable=FF/disable=00)(Needs Testing?)
5469 1 PA Sensor (enable=FF/disable=00)
546D 1 maybe injector test?
547D 1 VTEC VSS Check (enable=00/disable=FF) More info: Disable Vtec VSSCheck P72
547E 1 Debug Mode (0xFF enables, 0x00 disables) More info: P72 Debug Mode
5488 1 Serial Mode (FFh Enables UART Norm 9470bps)
5489 1 Iab control (0xFF enables, 0x00 disables)
58DA 1 Rev Resume #1 RPM = 1875000/(byte at this address)
58E0 1 Rev Cut #1
58E6 1 Rev Resume #2
58EC 1 Rev Cut #2 i think the following 4 points are wrong
595A 2 Rev Limit #1 more info...
5960 2 Rev Limit #2
5966 2 Rev Limit #3
596C 2 Rev Limit #4
59A0   Vtec auto (?)
59A2   Vtec manual (?)
5BA7   Idle Lookup table for 16-bit target idle RPM as a function of ECT
6059   Serial Comm Lookup table for RAM addresses that can be accessed using 9470 UART mode
7C9A   Low Fuel (10x20) more info...
7D6C   High Fuel (10x15)
7E0C   Low Timing (10x20)
7ED4   High Timing (10X15)
7C4A   MAP sensor scalers for fuel
7C54   MAP sensor scalers for ignition
7C5E   MAP sensor scalers for lambda table
7C68   Rev scalers low cam fuel/ignition
7C7C   Rev scalers high cam fuel/ignition
7C8B   Rev scalers lambda table
7C9A   Fuel map low cam
7D6C   Fuel map high cam
7E0C   Ignition map low cam
7ED4   Ignition map high cam
7F6A   Lambda map

Attachment?: Modify: Size: Date: Who: Comment:
P72OBD1top.jpg mod 227251 04 Mar 2004 - 00:44 blundar Picture of OBD1 P72 (thanks Katman)
P72NoKnockGoodchksum.bin mod 32768 05 Mar 2004 - 18:32 blundar P72 ROM with knock disabled + good checksum

Revision: r1.18 - 02 Apr 2006 - 02:18 GMT - 91crxsi { Edit | Attach | History | More }
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