Honda 2004 Odyssey Service Manual page 320

PCM Data
You can retrieve data from the PCM by connecting the OBD II scan tool or HDS to the data link connector (DLC). The
items listed in the table below conform to SAE recommended practice. The HDS also reads data beyond that
recommended by SAE to this data may help you find the causes of intermittent problems.
NOTE:
• The ''operating values'' listed are approximate and may vary depending on the environment and the individual
vehicle.
• Unless noted otherwise, ''at idle speed'' means idling with the engine completely warmed up, the transmission in
park or neutral, and the A/C and all accessories turned off.
Data
Diagnostic If the PCM detects a problem, it will store it as a code
Trouble Code consisting of one letter and 4 numbers. Depending on the
(DTC) problem, as SAE-defined code (P0xxx) or a Honda-defined
code (P1xxx) will be output to the tester.
Engine Speed The 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 fuel
injection.
Vehicle Speed The PCM converts pulse signals from the output shaft
(countershaft) speed sensor into speed data.
Manifold The absolute pressure caused in the intake manifold by
Absolute engine load and speed.
Pressure (MAP)
Engine Coolant The ECT sensor converts coolant temperature into voltage
Temperature and signals the PCM. The sensor is a thermistor with
(ECT) internal resistance that changes with coolant temperature.
The PCM uses the voltage signals from the ECT sensor to
determine the amount of injected fuel.
Primary Heated The HO2S detects the oxygen content in the exhaust gas
Oxygen Sensor and sends voltage signals to the PCM. Based on these
(Primary HO2S) signals, the PCM controls the air fuel ratio. When the
(Sensor 1), oxygen content is high (that is, when the ratio is leaner
Secondary than the stoichiometric ratio), the voltage signal is lower.
Heated Oxygen When the oxygen content is low (that is, when the ratio is
Sensor richer than the stoichiometric ratio), the voltage signal is
(Secondary higher.
HO2S)
(Sensor 2)
Description Operating Value Freeze Data
If no problem is
detected, there is no
output.
Nearly the same as
tachometer
indication
At idle speed: 730
50 rpm
Nearly the same as
speedometer
indication
With engine stopped:
Nearly the same as
atmospheric
pressure.
At idle speed: about
20 34 kPa (150
260 mmHg, 6 10
in.Hg), 0.9 1.1 V
With cold engine:
Same as ambient
temperature and IAT
With engine warmed
up: about 176 212°F
(80 100°C), 0.5
0.7 V
0.0 1.25 V
At idle speed:
about 0.1 0.9 V
YES
YES
YES
YES
YES
(cont'd)
11-11