engine coolant ACURA RL KA9 1996 Service User Guide

PCM Data

You can retrieve data from the 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 so that 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, transmission in Park or

neutral, and the A/C and all accessories turned off.

Data
Description
Operating Value

Freeze Data

Diagnostic

Trouble Code

(DTC)
If the 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 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.
Nearly the same as

tachometer indication at

idle speed:

650 ± 50 rpm
YES

Vehicle Speed
The PCM converts pulse signals from the Vehicle

Speed Sensor (VSS) into speed data.
Nearly the same as

speedometer indication
YES

Manifold

Absolute

Pressure (MAP)
The absolute pressure created in the intake manifold by

engine load and speed.
With engine stopped:

Nearly the same as atmo-

spheric pressure.

At idle speed:

24 - 37
kPa
(180
-
280

mmHg, 7.1 - 11.0 inHg)
YES

Engine Coolant

Temperature

(ECT)
The ECT sensor converts coolant temperature into

voltage and signals the PCM. The sensor is a thermistor

whose internal resistance changes with coolant

temperature. The PCM uses the voltage signals from

the ECT sensor to determine the amount of injected

fuel.
With cold engine:

Same as ambient temper-

ature and IAT

With engine warmed up:

approx. 158 - 212°F

(70 - 100°C)
YES

Heated Oxygen

Sensor (HO2S)

(Bank 1, Sensor 1)

(Bank 2, Sensor 1)

(Sensor 2)
The HO2S detects the oxygen content in the exhaust

gas and sends voltage signals to the PCM. Based on

these signals, the 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 ratio 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

NOProCarManuals.com

Intake Air System

System Description

The system supplies air for all engine needs. It consists of the intake air pipe. Air Cleaner, intake air duct. Throttle Body,

Idle Air Control (IAC) Valve, idle air control thermal valve, and intake manifold.

A resonator in the intake air pipe provides additional silencing as air is drawn into the system.

IMRC SOLENOID VALVE 2

IMRC

SOLENOID

VALVE 1
IMRC

VACUUM

TANK

From No. 20 ECU

(PCM)
(20 A)

FUSE

(in the under-dash

fuse/relay box)

IMRC

DIAPHRAGM

VALVE 1
VARIOUS

SENSORS

THROTTLE BODY
INTAKE

AIR

DUCT
INTAKE

MANIFOLD
IDLE

ADJUSTING

SCREW
With

TCS

IDLE AIR

CONTROL

THERMAL

VALVE
IAC

VALVE
From PGM-FI

MAIN RELAY

IMRC

DIAPHRAGM

VALVE 2
IMRC

CHECK

VALVE

ENGINE

COOLANTProCarManuals.com

Electronic Control System

The electronic control system consists of a Powertrain Control Module (PCM), sensors, a A/T clutch pressure control

solenoid and four solenoid valves. Shifting and lock-up are electronically controlled for comfortable driving under all con-

ditions. The PCM is located below the dashboard, under the front lower panel on the passenger's side.

PCM

Throttle Position Sensor

Signal

Engine Coolant Temperature

Sensor Signal

Indicator Light

Self-Diagnosis Signal
PGM-FI

Control System

Shift Control

Lock-up Control

A/T Control System

Self-Diagnosis

Function
Vehicle Speed Sensor

Signal

Service Check Connector

Shift Solenoid

Valve A

Shift Solenoid

Valve B

A/T Clutch Pressure Control

Solenoid Valve

Torque Converter Clutch

(Lock-up Control)

Solenoid Valve A

Torque Converter Clutch

(Lock-up Control)

Solenoid Valve B

Mainshaft Speed Sensor

Signal

Countershaft Speed

Sensor Signal
Interlock SystemProCarManuals.com

Grade Logic Control System

How it works:

The PCM compares actual driving conditions with driving conditions memorized in the PCM, based on the input from the

vehicle speed sensor, throttle position sensor, engine coolant temperature sensor, barometric pressure sensor, brake

pedal position switch signal and shift lever position signal, to control shifting while a vehicle is ascending or descending a

slope.ProCarManuals.com

Troubleshooting

TC-INH Signal (No PGM-FI DTC is indicated)

Check for a short to body ground

in the TC-INH circuit:

1. Disconnect the PCM connec-

tor C (12P) and TCS control

unit 14P connectors.

2. Check for continuity between

the PCM connector C (12P) ter-

minal No. 9 and body ground.

Is there continuity?

Check the PCM:

1. Connect the PCM connector C

(12P).

2. Start the engine.

3. Measure the voltage between

the PCM connector C (12P) ter-

minal No. 9 and body ground.

Does the tester needle swing

to about 2.5 V?

Check for an open in the TC-INH

circuit:

Measure the voltage between the

TCS control unit 14P connector

terminal No. 8 and body ground.

Does the tester needle swing

to about 2.5 V?

Check for loose TCS control unit

connectors. If necessary, substi-

tute a known-good TCS control

unit and recheck.
PCM CONNECTOR C (12P)

Repair short to body ground in

the wire between the PCM and

TCS control unit.
Wire side of female terminals

NOTE: Check under the following condi-

tions.

The coolant temperature is above 32°F

(0°C).

The MIL does not come on.

NOTE: Use the 10 V range or a similar

range in an analog tester.

Check for loose PCM connectors.

If necessary, substitute a known-

good PCM and recheck.

NOTE: Check under the following condi-

tions.

The coolant temperature is above 32°F

(0°C).

The MIL does not come on.

NOTE: Use the 10 V range or a similar

range in an analog tester.
TCS CONTROL UNIT UP CONNECTOR

Repair open in the wire between

the PCM and TCS control unit.

Wire side of female terminalsProCarManuals.com

Both Fans Low Speed

Both fans do not run at low speed

(but both fans run at high speed).

Check for an open in the wire:

1. Remove the radiator fan main

relay from the under-hood

relay box A.

2. Disconnect the radiator fan 2P

connector.

3. Check for continuity between

the No. 2 terminal of the radi-

ator fan main relay 5P socket

and the No. 2 terminal of the

radiator fan 2P connector.
NOTE: It is normal for both fans to run at high speed when the system pressure is above

1,520 kPa (15.5 kgf/cm2, 220 psi), or when the engine coolant temperature is above 194°F

(90°C).

RADIATOR FAN 2P CONNECTOR

Wire side of female terminals

RADIATOR FAN MAIN RELAY 5P SOCKET

Is there continuity?
Repair open in the wire between

the radiator fan main relay and

the radiator fan.

Replace the radiator fan main

relay.ProCarManuals.com