Fuel and Emissions System Description - Supplement

ECM/PCM Data


You can retrieve data from the ECM/PCM by connecting the scan tool or the Honda PGM Tester to the Data Link Connector (DLC). The items listed in the table below conform to SAE recommended practice. The Honda PGM Tester also reads data beyond that recommended by SAE so that this data may help you find the causes of intermittent problems.

NOTE:

Data Description Operating Value Freeze Data 
Diagnostic Trouble Code (DTC) If the ECM/PCM detects a problem, it will store it as a code consisting of one letter and four numbers. Depending on the problem, an SAE-defined code (P0xxx) or a Honda-defined code (P1xxx) will be output to the tester. If no problem is detected, there is no output. YES 
Engine Speed The ECM/PCM computes engine speed from the signals sent from the Crankshaft Position (CKP) sensor. This data is used for determining the time and amount of injected fuel. Nearly the same as tachometer indication
At idle speed:
750±50 rpm (min-1
YES 
Vehicle Speed The ECM/PCM converts pulse signals from the Vehicle Speed Sensor (VSS). Nearly the same as speedometer indication YES 
Manifold Absolute Pressure (MAP) The absolute pressure caused in the intake manifold by engine load and speed. With engine stopped: Nearly the same as atmospheric pressure
At idle speed: about 20-34 kPa (150-260 mmHg, 6-10 in. Hg), 0.7-1.1 V 
YES 
Engine Coolant Temperature (ECT) The ECT sensor converts coolant temperature into voltage and signals the ECM/PCM. The sensor is a thermistor whose internal resistance changes with coolant temperature. The ECM/PCM uses the voltage signals from the ECT sensor to determine the amount of injected fuel. With cold engine: Same as ambient temperature and IAT
With engine warmed up: about 80-100°C (176-212°F), 0.5-0.8 V 
YES 
Heated Oxygen Sensor (HO2S) The HO2S detects the oxygen content in the exhaust gas and sends voltage signals to the ECM/PCM. Based on these signals, the ECM/PCM controls the air fuel ratio. When the oxygen content is high (that is, when the ratio is leaner than the stoichiometric ratio), the voltage signal is lower. When the oxygen content is low (that is, when the radio is richer than the stoichiometric ratio), the voltage signal is higher. 0.0-1.25 V
At idle speed:
about 0.1-0.9 V 
NO 

Data Description Operating Value Freeze Data 
Fuel System Status Fuel system status is indicated as ‘‘open'' or ‘‘closed''.
Closed: Based on the HO2S output, the ECM/PCM determines the air/fuel ratio and controls the amount of injected fuel.
Open: ignoring the HO2S output, the ECM/PCM refers to signals from the Throttle Position (TP), Manifold Absolute Pressure (MAP), Intake Air Temperature (IAT), Barometric Pressure (BARO) and Engine Coolant Temperature (ECT) sensors to control the amount of injected fuel. 
At idle speed: closed YES 
Short Term Fuel Trim The air/fuel ratio correction coefficient for correcting the amount of injected fuel when the Fuel System Status is ‘‘closed.'' When the ratio is leaner than the stoichiometric ratio, the ECM/PCM increases short term fuel trim gradually, and the amount of injected fuel increases. The air/fuel ratio gradually gets richer, causing a lower oxygen content in the exhaust gas. Consequently, the short term fuel trim is lowered, and the ECM/PCM reduces the amount of injected fuel.
This cycle keeps the air/fuel ratio close to the stoichiometric ratio when in closed loop status. 
0.70-1.47 YES 
Long Term Fuel Trim Long term fuel trim is computed from short term fuel trim and indicates changes occurring in the fuel supply system over a long period.
If long term fuel trim is higher than 1.00, the amount of injected fuel must be increased. If it is lower than 1.00, the amount of injected fuel must be reduced. 
0.72-1.35 YES 
Intake Air Temperature (IAT) The IAT sensor converts intake air temperature into voltage and signals the ECM/PCM. When intake air temperature is low, the internal resistance of the sensor increases, and the voltage signal is higher. With cold engine:
Same as ambient temperature and ECT 
YES 
Throttle Position Based on the accelerator pedal position, the opening angle of the throttle valve is indicated. At idle speed:
about 10 %, 0.5 V 
YES 
Ignition Timing Ignition timing is the ignition advance angle set by the ECM/PCM. The ECM/PCM matches ignition timing to the driving conditions. At idle speed: 8° ± 5°
BTDC when the SCS service signal line is jumped with the Honda PGM tester 
NO 
Caluculated Load Valve (CLV) CLV is the engine load calculated from the MAP data. At idle speed:
12-34 %
At 2,500 rpm (min-1) with no load:
15-25 % 
YES 

Vacuum Distribution


 

ECM/PCM Inputs and Outputs at Connector A (31P)

 

NOTE: Standard battery voltage is 12 V.

Terminal number Wire color Terminal name Description Signal 
BLK/WHT O2SHTC (HEATED OXYGEN SENSOR (HO2S) HEATER CONTROL) Drives HO2S heater With ignition switch ON (II): battery voltage
With fully warmed up engine running: duty controlled 
YEL/BLK IGP2 (POWER SOURCE) Power source for the ECM/PCM circuit With the ignition switch ON (II): battery voltage
With the ignition switch OFF: about 0 V 
YEL/BLK IGP1 (POWER SOURCE) Power source for the ECM/PCM circuit With the ignition switch ON (II): battery voltage
With the ignition switch OFF: about 0 V 
BLK PG2 (POWER GROUND) Ground for the ECM/PCM circuit Less than 1.0 V at all times 
BLK PG1 (POWER GROUND) Ground for the ECM/PCM circuit Less than 1.0 V at all times 
WHT HO2S (HEATED OXYGEN SENSOR (HO2S) SENSOR 1) Detects HO2S sensor signal With throttle fully opened from idle with fully warmed up engine: about 0.6 V
With throttle quickly closed: below 0.4 V 
BLU CKP (CRANKSHAFT POSITION SENSOR) Detects CKP sensor signal With engine running: pulses 
RED/BLU KS (KNOCK SENSOR) Detects knock sensor signal With engine knocking: pulses
With ignition switch ON (II): about 0 V 
10 GRN/BLK SG2 (SENSOR GROUND) Sensor ground Less than 1.0 V at all times 
11 GRN/WHT SG1 (SENSOR GROUND) Sensor ground Less than 1.0 V at all times 
12 BLK/BLU IACV (IDLE AIR CONTROL (IAC) VALVE) Drives IAC valve With engine running: duty controlled 
13 WHT/BLK EGRP (EXHAUST GAS RECIRCULATION (EGR) VALVE POSITION SENSOR) Detects EGR valve position sensor signal With engine running: 1.2 V-2.0 V (depending on EGR valve lift) 
15 RED/BLK TPS (THROTTLE POSITION (TP) SENSOR) Detects TP sensor signal With throttle fully open: about 4.8 V
With throttle fully closed: about 0.5 V 

ECM/PCM Inputs and Outputs at Connector A (31P)

 

NOTE: Standard battery voltage is 12 V.

Terminal number Wire color Terminal name Description Signal 
   18*2 BLU/WHT VSS (VEHICLE SPEED SENSOR (VSS)) Detects VSS signal With ignition switch ON (II) and front wheels rotating: cycles 0 V-about 5 V or battery voltage 
   18*1 BLU/WHT VABS (VEHICLE SPEED SIGNAL FROM ABS) Input vehicle speed from ABS control unit Depending on vehicle speed: pulses 
19 RED/GRN MAP (MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR) Detects MAP sensor signal With ignition switch ON (II): about 3 V
At idle: about 1.0 V (depending on engine speed) 
20 YEL/BLU VCC2 (SENSOR VOLTAGE) Provides sensor voltage With ignition switch ON (II): about 5 V
With ignition switch OFF: about 0 V 
21 YEL/RED VCC1 (SENSOR VOLTAGE) Provides sensor voltage With ignition switch ON (II): about 5 V
With ignition switch OFF: about 0 V 
23 BRN/BLK LG2 (LOGIC GROUND) Ground for the ECM/PCM circuit Less than 1.0 V at all times 
24 BRN/BLK LG1 (LOGIC GROUND) Ground for the ECM/PCM circuit Less than 1.0 V at all times 
26 GRN TDC (TOP DEAD CENTER (TDC) SENSOR) Detects DTC sensor With engine running: pulses 
27 WHT/BLU IGPLS4 (No. 4 IGNITION COIL PULSE) Drives No. 4 ignition coil With ignition switch ON (II): about 0 V
With engine running: pulses 
28 WHT/BLK IGPLS3 (No. 3 IGNITION COIL PULSE) Drives No. 3 ignition coil 
29 WHT/GRN IGPLS2 (No. 2 IGNITION COIL PULSE) Drives No. 2 ignition coil 
30 WHT IGPLS1 (No. 1 IGNITION COIL PULSE) Drives No. 1 ignition coil 
*1: CVT
*2: M/T

ECM/PCM Inputs and Outputs at Connector B (24P)

 

NOTE: Standard battery voltage is 12 V.

Terminal number Wire color Terminal name Description Signal 
YEL INJ4 (No. 4 INJECTOR) Drives No. 4 injector With ignition switch ON (II): battery voltage
At idle: duty controlled 
BLU INJ3 (No. 3 INJECTOR) Drives No. 3 injector 
RED INJ2 (No. 2 INJECTOR) Drives No. 2 injector 
BRN INJ1 (No. 1 INJECTOR) Drives No. 1 injector 
GRN FANC (RADIATOR FAN CONTROL) Drives radiator fan relay With radiator fan running: about 0 V
With radiator fan stopped: battery voltage 
   7*1 GRN/WHT DNLS+ (CVT DRIVEN PULLEY CONTROL VALUE+ SIDE) Drives CVT driven pulley control value With ignition switch ON (II): pulsing signal 
RED/WHT ECT (ENGINE COOLANT TEMPERATURE SENSOR) Detects ECT sensor signal With the ignition switch ON (II): about 0.1-4.8 V
(depending on engine coolant temperature) 
   11*1 RED/WHT M IND (M INDICATOR) Drives M indicator light. With M indicator light turned ON : about 6 V
With M indicator light turned OFF : 0 V voltage 
   12*1 LT GRN S IND (S INDICATOR) Drives S indicator light. With S indicator light turned ON : about 6 V
With S indicator light turned OFF : 0 V voltage 
13 WHT/RED ALTF (ALTERNATOR FR SIGNAL) Detects alternator FR signal With engine running:about 0 V-5 V
(depending on electrical load) 
14 PNK EGR (EXHAUST GAS RECIRCULATION (EGR) VALVE) Drives EGR valve With EGR operating: duty controlled
With EGR not operating: about 0 V 
15 GRN/YEL VTS (VTEC SOLENOID VALVE) Drivers VTEC solenoid valve At idle: about 0V 
   16*1 YEL SCLS+ (CVT START CLUTCH PRESSURE CONTROL VALVE + SIDE Drives CVT start clutch pressure control valve With ignition switch ON (II): pulsing signal 
17 RED/YEL IAT (INTAKE AIR TEMPERATURE SENSOR) Detects IAT sensor signal With ignition switch ON (II): about 0.1 V-4.8 V
(depending on intake air temperature) 
18 WHT/GRN ALTC (ALTERNATOR CONTROL) Sends alternator control signal With engine running: about 0 V-5 V
(depending on electrical load) 
   19*1 LT GRN/RED S-DN (DOWN SHIFT SWITCH) Detects downshift switch signal Steering shift switch pushed toward downshift position (marked with -): 0 V
Steering shift switch in neutral position : about 5 V 
   20*1 YEL S-UP (UP SHIFT SWITCH) Detects upshift switch signal Steering shift switch pushed toward upshift position (marked with +): 0 V
Steering shift switch in neutral position : about 5 V 
21 RED/YEL PCS (EVAPORATIVE EMISSION (EVAP) CANISTER PURGE VALVE) Drives EVAP canister purge valve With engine running, engine coolant below 65°C (149°F): about 0 V
With engine running, engine coolant above 65°C (149°F): duty controlled 
   24*1 BLU/WHT DRLS+ (CVT DRIVE PULLEY CONTROL VALVE + SIDE) Drives CVT drive pulley control valve With ignition switch ON (II): duty controlled 

*1: CVT 

PCM Inputs and Outputs at Connector C (22P)*1

 

NOTE: Standard battery voltage is 12 V.

Terminal number Wire color Terminal name Description Signal 
PNK/BLK DNLS- (CVT DRIVEN PULLEY CONTROL VALVE - SIDE Drives CVT driven pulley control valve  
BLK PG (CVT2) (POWER GROUND CVT2) Ground for the PCM circuit  
BLK PG (CVT1) (POWER GROUND CVT1) Ground for the PCM circuit  
GRN/BLK INHSOL (INHIBITOR SOLENOID CONTROL) Drives inhibitor solenoid With inhibitor solenoid ON: battery voltage
With inhibitor solenoid OFF: 0 V 
RED/BLU NDR (CVT DRIVE PULLEY SPEED SENSOR) Detects CVT drive pulley speed sensor signal With ignition switch ON (II): 0 V or 5 V 
PNK/BLU SCLS- (CVT START CLUTCH PRESSURE CONTROL VALVE B-SIDE) Drives CVT start clutch pressure control valve  
BLU/WHT ATPS (TRANSMISSION RANGE SWITCH S POSITION) Drives transmission range switch S position signal In S position: 0 V
In any other position: about 5 V or battery voltage 
10 WHT ATPR (TRANSMISSION RANGE SWITCH R POSITION) Detects transmission range switch R position signal In R position: 0 V
In any other position: about 10 V 
11 BLU ATPL (TRANSMISSION RANGE SWITCH L POSITION) Detects transmission range switch L position signal In L position: 0 V
In any other position: about 10 V 
12 LT GRN ATPNP (TRANSMISSION RANGE SWITCH NEUTRAL/PARK POSITION) Detects transmission range switch Neutral/Park position signal In Park or Neutral: 0 V
In any other position: about 10 V 
13 YEL MSW (MAIN SWITCH) Detects main switch
(7SPEED MODE) signal 
Main switch (7SPPED MODE) pushed: 0 V
Main switch (7SPPED MODE) released: about 5 V 
15 WHT NDN (CVT DRIVEN PULLEY SPEED SENSOR) Detects CVT driven pulley speed sensor signal With ignition switch ON (II): 0 V or 5 V 
16 GRN/YEL DRLS- (CVT DRIVE PULLEY CONTROL VALVE-SIDE) Drives CVT drive pulley control valve With ignition switch ON (II): pulses 
20 PNK ATPD (TRANSMISSION RANGE SWITCH D POSITION) Detects transmission range switch D position signal In D position: about 0 V
In any other position: about 5 V 
22 WHT/RED VEL1 (CVT SPEED SENSOR) Detects CVT speed sensor Depending on vehicle speed: pulses
When vehicle is stopped: about 0 V or about 5 V 

*1: CVT 

ECM/PCM Inputs and Outputs at Connector E (31P)

 

NOTE: Standard battery voltage is 12 V.

Terminal number Wire color Terminal name Description Signal 
GRN/YEL IMO FPR (IMMOBILIZER FUEL PUMP RELAY) Drives PGM-FI main relay 2 0 V for 2 seconds after turning ignition switch ON (II), then battery voltage 
BRN/YEL LG3 (LOGIC GROUND) Ground for the PCM control circuit Less than 0.1 V at all times 
PNK SG3 (SENSOR GROUND) Sensor ground Less than 0.1 V at all times 
GRN/WHT FUP (FUEL INJECTION SIGNAL) Sends fuel injection signal to gauge assembly With ignition switch ON (II): pulses 
RED/YEL MRLY(PGM-FI MAIN RELAY) Drives PGM-FI main relay 1 Power source for the DTC memory With ignition switch ON (II): about 0 V
With ignition switch OFF: battery voltage 
   8*1 BLU/WHT LED A Drives shift indicator In 7SPEED MODE:
  • in 1st, 2nd, 3rd and 7th: about 0.3 V
  • in 4th, 5th, and 6th: about 5 V
 
BLK/YEL IG1 (IGNITION SIGNAL) Detects ignition signal With ignition switch ON (II): battery voltage
With ignition switch OFF: about 0 V 
11 PNK DIND (D INDICATOR) Drives D indicator light With D indicator light turned ON: about 6 V
With D indicator light turned OFF: 0 V 
12 BLU TAC Detects evaporator sensor signal With ignition switch ON (II): about 0.1-4.8 V (depending on evaporator temperature) 
13*1 BLU/RED SLC (SHIFT LOCK CONTROL) Drives shift lock solenoid With ignition switch ON (II) ,in Park position,brake pedal pressed,and accelerator pedal released: 0V 
15 GRN/RED ELD (ELECTRICAL LOAD DETECTOR (ELD)) Detects ELD signal With ignition switch ON (II): about 0.1-4.8 V (depending on electrical load) 

*1: CVT 

ECM/PCM Inputs and Outputs at Connector E (31P)

 

NOTE: Standard battery voltage is 12 V.

Terminal number Wire color Terminal name Description Signal 
18 RED ACC (A/C CLUTCH RELAY) Drives A/C clutch relay With compressor ON: about 0 V
With compressor OFF: battery voltage 
   20*1 GRN/BLK LED C Drives shift indicator In 7SPEED MODE:
  • in 2nd, 4th, 6th and 7th: about 0.3 V
  • in 1st, 3rd and 5th: about 5 V
 
   21*1 RED/WHT LED B Drives shift indicator In 7SPEED MODE:
  • in 1st, 4th, 5th and 7th: about 0.3 V
  • in 2nd, 3rd and 6th: about 5 V
 
22 WHT/BLK BKSW (BRAKE PEDAL POSITION SWITCH) Detects brake pedal position switch signal With brake pedal released: about 0 V
With brake pedal pressed: battery voltage 
23 RED/WHT K-LINE Sends and receives scan tool signal With ignition switch ON (II): battery voltage 
24 GRN MTRTW Sends engine coolant temperture signal With ignition switch ON (II): pulse 
25 BLU/YEL VSSOUT (VEHICLE SPEED SENSOR (VSS) OUTPUT SIGNAL) Sends vehicle speed sensor signal Depending on vehicle speed: pulses 
26 BLU NEP (ENGINE SPEED PULSE) Outputs engine speed pulse With engine running: pulses 
27 RED/BLU IMOCD (IMMOBILIZER CODE) Detects immobilizer signal  
28 BLU/WHT ACS (A/C SWITCH SIGNAL) Detects A/C switch signal With A/C switch ON: 0 V
With A/C switch OFF: about 5 V 
29 BRN SCS (SERVICE CHECK SIGNAL) Detects service check signal With the service check signal shorted with the PGM Tester: about 0 V
With the service check signal opened: about 5 V 
30 RED/BLU WEN (WRITE ENABLE SIGNAL) Detects write enable signal With ignition switch ON (II): about 0V 
31 GRN/ORN MIL (MALFUNCTION INDICATOR LAMP) Drives MIL With MIL turned ON: about 0 V
With MIL turned OFF: battery voltage 

*1: CVT 

ECM/PCM Circuit Diagram


 

ECM/PCM Circuit Diagram (cont'd)


 

 

ECM/PCM Circuit Diagram (cont'd)


 

 

ECM/PCM Circuit Diagram (cont'd)


 

ECM/PCM Circuit Diagram (cont'd)



 

 

ECM/PCM Circuit Diagram (cont'd)



 

 

ECM/PCM Circuit Diagram (cont'd)



 

 

ECM/PCM Circuit Diagram (cont'd)



 

 

ECM/PCM Circuit Diagram (cont'd)


 

 

ECM/PCM Circuit Diagram (cont'd)