1995 ACURA TL check engine light

Idle Contro l Syste m
Alternato r (ALT ) F R Signa l
This signal s th e EC M whe n th e Alternato r (ALT ) i s charging .
Is ther e approx . 5 V ?
Chec k th e operatio n o f th e ALT :
1 . Tur n th e ignitio n switc h OFF .
2 . Reconnec t th e AL T GR N 4 P
connecto r t o th e ALT .
3 . Star t th e engine . Hol d th e
engin e a t 3,00 0 rp m wit h n o
loa d (transmissio n in o r
position ) unti l th e radiato r fa n
come s on , the n le t i t idle .
4 . Measur e voltag e betwee n EC M
connecto r terminal s D 5 an d A26 .
Doe s th e voltag e decreas e whe n
headlight s an d rea r defogge r ar e
turne d on ?
Chec k fo r a n ope n in th e wir e (AL T
F line) :
1. Tur n th e ignitio n switc h OFF .2. Disconnec t th e negativ e bat -
ter y cabl e fro m th e battery .
3 . Disconnec t th e EC M connec -
tor D (22P) .4. Disconnec t th e GR N 4 P con -
necto r fro m th e ALT .
5 . Connec t th e AL T 4 P connecto r
termina l No . 4 to bod y groun d
with a jumpe r wire .6. Chec k fo r continuit y betwee nbody groun d an d EC M con -necto r termina l D5 .
I s ther e continuity ?
Se e th e AL T inspectio n (se e
sectio n 23 ). EC
M CONNECTOR S
A (26P)D (22P)
Wire sid e o f femal e terminal s
D (22P)
Repai r shor t i n th e wir e betwee nthe EC M (D5 ) and th e ALT .
ALT F R signa l i s OK .
ALT GR N 4P CONNECTO R (C127 )
JUMPE R WIR E
Wir e sid e o f femal e terminal s
Repai r ope n wir e betwee n th e
ECM (D5 ) and th e ALT .
ECM CONNECTO R D (22P )
Wir e sid e o f femal e terminal s
Substitut
e a known-goo d EC M
an d recheck . I f prescribe d voltag e
i s no w available , replac e th e origi -
nal ECM .
Is ther e continuity ?
Chec
k fo r a shor t i n th e wir e (AL T
F line) :
1 . Tur n th e ignitio n switc h OFF .
2 . Disconnec t th e negativ e bat -
ter y cabl e fro m th e battery .
3 . Disconnec t th e EC M connecto r
D (22P) .4. Chec k fo r continuit y betwee n
bod y groun d an d EC M con -
necto r termina l D5 .
Chec
k fo r a shor t i n th e wir e (AL T
F line) :
1 . Disconnec t th e GR N 4 P con -
necto r fro m th e ALT .
2 . Tur n th e ignitio n switc h O N (II) .
3 . Measur e voltag e betwee n EC M
connecto r terminal s D 5 an d A26 .
Inspectio
n o f AL T F R Signal .
ProCarManuals.com

Idle Spee d Settin g
Inspection/Adjustmen t
NOTE:
• Befor e settin g th e idl e speed , chec k th e followin g
items:
— Th e MI L ha s no t bee n reporte d on .
— Ignitio n timin g
— Spar k plug s
— Ai r cleane r
— PC V syste m
• (Canada ) Pul l th e parkin g brak e leve r up . Star t th e
engine , the n chec k tha t th e headlight s ar e off .
1 . Star t th e engine . Hol d th e engine at 3,00 0 rp m wit h
no loa d (transmissio n i n o r position ) unti l th e
radiato r fa n come s on , the n le t i t idle .
2 . Connec t a tachometer .
3 . Disconnec t th e IA C valv e connector .
IAC VALV E
4.
5.
Star t th e engin e wit h th e accelerato r peda l slightl y
depressed . Stabiliz e th e rp m a t 1,000 , the n slowl y
releas e th e peda l unti l th e engin e idles .
Check idlin g in no-loa d conditions : headlights , blow -
er fan , rea r defogger , radiato r fan , an d ai r conditione r
ar e no t operating .
Idl e spee d shoul d be :
550 ± 5 0 rp m
(in o r position )
Adjust th e idl e speed , i f necessary, by turnin g th e
idl e adjustin g screw .
NOTE : Afte r adjustin g th e idl e spee d i n thi s step ,
rechec k th e ignitio n timin g (se e sectio n 23 ).
I f i t i s ou t o f spec , g o bac k t o ste p 4 .
IDL E ADJUSTIN G SCRE W
6. Tur n th e ignitio n switc h OFF .
7 . Reconnec t th e 2 P connecto r o n th e IA C valve , the n
d o th e EC M rese t procedure .
8 . Restar t an d idl e th e engine with no-loa d condition s
fo r on e minute , the n chec k th e idl e speed .
NOTE : (Canada ) Pul l th e parkin g brak e leve r up .
Star t th e engine , the n chec k tha t th e headlight s ar e
off.
Idle spee d shoul d be :
700 ± 5 0 rp m
(in o r position )
9 . Idl e th e engin e fo r on e minut e wit h headlight s (Low )
O N an d chec k th e idl e speed .
Idl e spee d shoul d be :
770 ± 5 0 rp m
(in o r position )
10 . Tur n th e headlight s off .
Idl e th e engin e fo r on e minut e wit h heate r fa n switc h
a t H I an d ai r conditione r on , the n chec k th e idl e speed .
Idl e spee d shoul d be :
770 ± 5 0 rp m
(in o r position )
NOTE : I f th e idl e spee d i s no t withi n specification ,
se e Sympto m Char t o n pag e 11-36 .
ProCarManuals.com

Positive Crankcase Ventilation (PCV) System

Description

The Positive Crankcase Ventilation (PCV) system is

designed to prevent blow-by gas from escaping to the

atmosphere. The PCV valve contains a spring-loaded

plunger. When the engine starts, the plunger in the PCV

valve is lifted in proportion to intake manifold vacuum and

the blow-by gas is drawn directly into the intake manifold.

BREATHER

HOSE

PCV VALVE
BLOW-BY VAPOR

FRESH AIR
Inspection

1. Check the PCV hoses and connections for leaks and

clogging.

PCV HOSE

PCV VALVE

2.
BREATHER

PIPE

At idle, make sure there is a clicking sound from the

PCV valve when the hose between PCV valve and

intake manifold in lightly pinched with your fingers

or pliers.

Gently pinch here

If there is no clicking sound, check the PCV valve

grommet for cracks or damage. If the grommet is

OK, replace the PCV valve and recheck.
INTAKE

MANIFOLDProCarManuals.com

Description

The electronic control system consists of the Transmission Control Module (TCM), sensors, a linear solenoid, and four

solenoid valves.

Shift and lock-up are electronically controlled for comfortable driving under all conditions.

The TCM is located below the dashboard, behind the glove box on the passenger's side.

TCM

Linear Solenoid

Shift Control

Solenoid Valve A

Shift Control

Solenoid Valve B

Lock-up Control

Solenoid Valve A

Lock-up Control

Solenoid Valve B

Engine Speed Signal

Brake Switch Signal

Mainshaft Speed Sensor

Signal

Countershaft Speed

Sensor Signal

Vehicle Speed Sensor

Signal

Indicator Light

Self-Diagnosis Signal
Electronic Control System

Shift Control

Lock-up Control
Throttle Position

Sensor Signal

Engine Coolant

Temperature

Sensor Signal

Service Check

Connector

Barometric

Pressure Sensor

INTERLOCK

CONTROL UNIT

Self-Diagnosis

FunctionProCarManuals.com

8.
Set the control shaft to the position, then install

the A/T gear position switch on the control shaft

and install the clamp on the rear cover.

SHIFT CABLE

CONTROL

LEVER

9. Connect the A/T gear position switch connector,

then install the harness stay.

10. Turn the ignition switch ON (II). Move the shift lever

through all gears, and check the A/T gear position

switch synchronization with the A/T gear position

indicator.

11. If the A/T gear position switch does not synchronize

with the A/T gear position indicator, loosen the

bolts securing the A/T gear position switch and

adjust the A/T gear position switch installation.

GAUGE ASSEMBLY

A/T GEAR

POSITION INDICATOR
12. Install the A/T gear position switch cover. Tighten

the bolt on the ATF pan side loosely so that there is

no clearance between the A/T gear position switch

cover and the ATF pan. Then tighten the bolt on the

rear cover side to the specified torque, and tighten

the bolt on the ATF pan side to the specified torque.

6 x 1.0 mm

(Rear cover side)

12 N-m (1.2 kgf-m,

8.7 Ibf-ft)

A/T GEAR POSITION

SWITCH COVER
ATF PAN

6 x 1.0 mm (ATF pan side)

12 N-m (1.2 kgf-m, 8.7 Ibf-ft)

13. Start the engine. Move the shift lever through all

gears, and verify the following:

• The shift lever cannot be moved to the posi-

tion from the position without pushing the

shift lever.

• The engine will not start in any gear, only in the

or position.

• The back-up lights come on when the shift lever

is in the position.ProCarManuals.com

Brake Booster

Inspection

Functional Test

1. With the engine stopped, depress the brake pedal

several times to deplete the vacuum reservoir, then

depress the pedal hard and hold it for 15 seconds. If

the pedal sinks, either the master cylinder is

bypassing internally, or the brake system (master

cylinder, lines, modulator, proportioning valve, or

caliper) is leaking.

2. Start the engine with the pedal depressed. If the

pedal sinks slightly, the vacuum booster is operat-

ing normally. If the pedal height does not vary, the

booster or check valve is faulty.

3. With the engine running, depress the brake pedal

lightly. Apply just enough pressure to hold back

automatic transmission creep. If the brake pedal

sinks more than 25 mm (1.0 in.) in three minutes, the

master cylinder is faulty. A slight change in pedal

height when the A/C compressor cycles on and off if

normal. (The A/C compressor load changes the vac-

uum available to the booster.)

Leak Test

1. Depress the brake pedal with the engine running,

then stop the engine. If the pedal height does not

vary while depressed for 30 seconds, the vacuum

booster is OK. If the pedal rises, the booster is faulty.

2. With the engine stopped, depress the brake pedal

several times using normal pressure. When the

pedal is first depressed, it should be low. On consec-

utive applications, the pedal height should gradually

rise. If the pedal position does not vary, check the

booster check valve.ProCarManuals.com

Pump motor control:

The ABS control unit monitors the brake fluid pressure in the accumulator by the pressure switch ON/OFF signals. The

ABS control unit turns the pump on when the pressure in the accumulator drops, and stops the pump when the pressure

rises to the specified value.

If the pressure does not reach the specified value after the motor has operated continuously for a specified period, the

ABS control unit stops the motor and activates the ABS indicator light.

Self-diagnosis function:

The self-diagnosis function, provided in the sub-function of the ABS control unit, monitors the main system functions by

constantly transmitting the data between the two Central Processing Units (CPUs). When an abnormality is detected, the

ABS control unit turns the ABS indicator light on and stops the ABS, although the basic brake system continues to operate

normally.

When the ABS control unit detects an abnormality with the ABS and turns the ABS indicator light on, the diagnostic trou-

ble code (DTC), which shows the problem part or unit, is recorded in the control unit. The DTC can be read by the blinking

frequency of the ABS indicator light.

Fail-safe function:

When an abnormality is detected in the ABS control sys-

tem self-diagnosis, the solenoid operations are suspend-

ed by turning off the two fail-safe relays. This discon-

nects the ground circuits of all the solenoid valves to

prevent ABS operation.

Under these conditions, the braking system functions

just as an ordinary one.

Fail-safe relay:

The fail-safe relay's terminal side contact is normally

open. When there is continuity at the relay coil, the fail-

safe relay is closed, thereby connecting the ground cir-

cuit to the solenoid valve.

ABS indicator light:
SOLENOID VALVE

BAT

REAR FAIL-SAFE RELAY

FRONT FAIL-SAFE RELAY

The ABS control unit turns the ABS indicator light on when one or more of the following abnormalities are detected. This

is only a partial list.

When the operating time of the motor in the power unit exceeds the specified period.

When vehicle running time exceeds 30 seconds without releasing the parking brake.

When absence of speed signals from any of the four wheel sensor is detected.

When the activation time of all solenoids exceeds a given time, or an open circuit is detected in the solenoid system.

When solenoid output is not detected in the simulated ABS operation when the engine is started or the vehicle is driven.

To check the indicator light bulb, the light is activated when the ignition switch is first turned on. The light goes off after

the engine is started if there is no abnormality in the system.
ABS CONTROL UNITProCarManuals.com

Troubleshooting Precautions

ABS Indicator Light:

The ABS indicator light comes on for three seconds and then goes off when the control unit detects no problem during the

initial diagnosis right after the engine starts. However, the ABS indicator light can stay on for up to 40 seconds when the

control unit starts to check for pump overrun, etc. during the initial diagnosis. The ABS indicator light comes on, and the

ABS control unit memorizes the diagnostic trouble code (DTC) under certain conditions.

The parking brake is applied for more than 30 seconds while the vehicle is being driven. (DTC 2-1)

The transmission downshifted excessively. (DTC 4-1, 4-2)

The vehicle loses traction, and the front wheels spin for more than one minute when starting from a stuck condition on

a muddy, snowy, or sandy road. (DTC 4-8)

Tire adhesion is lost due to excessive cornering speed. (DTC 5, 5-4, 5-8)

The vehicle is driven on an extremely rough road. (DTC 8-1)

The vehicle is interfered by strong radio waves (noise), for example, illegal radio, etc. (DTC 8-2)

NOTE: If there is any trouble in the system, the ABS indicator light comes on during driving.

Diagnostic Trouble Code (DTC):

When the control unit detects a problem and the ABS indicator light comes on, the control unit memorizes the DTC.

The control unit has three memory registers. When a problem occurs, the control unit stores the DTC in the first memory

register. If another problem occurs, or the same problem occurs again, the control unit moves the first DTC to the next

memory register, and stores the second DTC in the first register. If there's a third problem occurrence, the two existing

DTCs are moved up one register, and the third DTC is stored in the first register. If problems continue to occur, the oldest

problem is moved out of the last register and lost, and the most recent problem is stored in the first register. When the

same problem occurs three times, the same DTC is stored in all memory registers. (Refer to the Symptom-to-System

Chart for diagnostic period.)

The most recent DTC is indicated first, and the oldest DTC is indicated last.

The DTCs are erased from the control unit when the ABS control unit +B2 power supply or connector is disconnected.

The control unit's memory can be erased by disconnecting the ABS B2 fuse for more than three seconds.

Self-diagnosis:

There are three self-diagnosises described below.

Initial diagnosis: Performed right after the engine starts until the ABS indicator light goes off.

Regular diagnosis: Continuously performed (under some conditions) after the ABS indicator light goes off until the

engine stops.

Individual part/system diagnosis: Diagnosis about a specific part/system under its operating conditions.

The CPU (central processing unit) controls the following when it detects a problem during self-diagnosis:

Turns the ABS indicator light ON.

Turns the front and rear fail-safe relays off.

Stops the ABS control.

Stops the ABS pump. (The pump may work under some conditions.)

After the DTC is stored in the control unit, the CPU stops self-diagnosis.ProCarManuals.com