Ecm/Pcm Data - Honda 2002 Accord Manual

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ECM/PCM Data
Y o u can retrieve data f r o m the ECM/PCM by connecting the OBD II 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 to help you find the causes of intermittent problems.
NOTE:
« The " o p e r a t i n g v a l u e s " listed are approximate and may vary depending on the environment and the individual
vehicle.
• Unless noted otherwise, " a t idle speed" means idling w i t h the engine completely w a r m e d up, A/T in park or neutral,
M/T in neutral position, and the A/C and all accessories turned off.
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, as SAE-defined code (POxxx) 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 f r o m the signals
sent f r o m the Crankshaft Position sensor. This data is
used for determining the t i m e and amount of fuel
injection.
Nearly the same as
tachometer indication
At idle speed: 7 0 0 ± 5 0
rpm
YES
Vehicle Speed
The ECM/PCM converts pulse signals f r o m the Vehicle
Speed Sensor (VSS) (M/T) or countershaft speed sensor
(A/T) into speed data.
Nearly the same as
speedometer
indication
YES
Manifold
Absolute
Pressure
(MAP)
The absolute pressure caused in the intake manifold by
engine load and speed.
W i t h engine stopped:
Nearly the same as
atmospheric pressure.
A t idle speed: about 21
- 4 1 kPa ( 1 6 0 - 3 1 0
m m H g , 6 . 3 - 1 2 . 2 inHg),
0 . 7 - 1 . 3 V
YES
Engine
Coolant
Temperature
(ECT)
The ECT sensor converts coolant temperature into voltage
and signals the ECM/PCM. The sensor is a thermistor
w i t h internal resistance that changes w i t h coolant
temperature. The ECM/PCM uses the voltage signals f r o m
the ECT sensor to determine the amount of injected fuel.
W i t h cold engine:
Same as ambient
temperature and IAT
W i t h engine w a r m e d
up: about 1 5 8 - 2 1 2 ° F
( 7 0 - 1 0 0 ° C ) 0.5 to 0.7
Volts
YES
Heated
Oxygen
Sensor (H02S)
(Primary,
Sensor 1)
(Secondary,
Sensor 2)
The Heated Oxygen Sensor 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. W h e n the oxygen content is high (that is,
when the ratio is leaner than the stoichiometric ratio), the
voltage signal is lower. W h e n the oxygen content is low
(that is, w h e n the ratio is richer than the stoichiometric
ratio), the voltage signal is higher.
0 . 0 - 1 . 2 5 V
At idle speed:
about 0 . 1 - 0 . 9 V
YES
(Primary,
Sensor 1
only)
Air Fuel Ratio
(A/F) Sensor,
(Sensor 1)
(F23A4
engine)
The A/F sensor 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, w h e n the ratio is
leaner than the stoichiometric ratio), the voltage signal is
lower. When the oxygen content is low (that is, w h e n the
ratio is richer than the stoichiometric ratio), the voltage
signal is higher. The A/F sensor signals are electrical
current that are indicated as voltage on the scan tool.
0 . 0 - 1 . 2 5 V
At idle speed:
about 0 . 1 - 0 . 9 V
NO
(cont'd)
11-11