1991 ACURA NSX service indicator

Troubleshooting Procedures

When the Transmission Control Module (TCM) senses an abnormality in the input or output systems, the indicator
light in the gauge assembly will blink. However, when the Service Check Connector (located to the lower right of the glove compartment) is connected with a jumper wire, the indicator light will blink the Diagnostic Trouble Code (DTC)

when the ignition switch is turned on.

When the indicator light has been reported on, connect the two terminals of the Service Check Connector together.
Then turn on the ignition switch and observe the indicator light.
Codes 1 through 9 are indicated by individual short blinks. Codes 10 through 16 are indicated by a series of long and
short blinks. One long blink equals 10 short blinks. Add the long and short blinks together to determine the code. After
determining the code, refer to the electrical system Symptom-to-Component Chart on page 14-52 and 53. SERVICE CHECK
CONNECTOR
Connect with jumper wire.

INDICATOR
Some PGM-FI problems will also make the indicator light come on After repairing the PGM-FI system, disconnect the
CLOCK fuse (7.5 A) in the main relay box for more than 10 seconds to reset the TCM memory.
long short
See DTC 1

See DTC 2

See DTC 14

LIGHT

short
PGM-FI system
The PGM-FI system on this model is a sequential multiport fuel injection system. Disconnecting the CLOCK fuse also cancels the radio preset stations and the clock setting. Make note of the radio
presets before removing the fuse so you can reset them.

NOTE:ProCarManuals.com

Symptom-to-Component Chart
Electrical System
Number of indicator light

blinks while Service Check
Connector is jumped.
When the ignition

switch is turned on,
indicator light
1

Blinks

Possible Cause


Symptom

Lock-up clutch does not

engage.
Lock-up clutch does not

disengage.
Unstable idle speed.
Refer to

page

14-54

14-55

14-56

14-57

14-58

14-60
14-62
14-63
14-64
14-66

Lock-up clutch does not

engage.
Lock-up clutch does not

engage.
Fails to shift (stuck in 1 st or 4th

gears).
Fails to shift other than 2nd

4th gears.
Lock-up clutch does not

engage.
Lock-up clutch engages and
disengages alternately. Fails to shift other than 2nd

4th gears.
Lock-up clutch does not

engage.
Lock-up clutch does not

engage.
Lock-up clutch does not

engage.
Lock-up clutch does not

engage.

Disconnected lock-up control
solenoid valve A connector Short or open in lock-up control
solenoid valve A wire
Faulty lock-up control solenoid
valve A
Disconnected lock-up control
solenoid valve B connector Short or open in lock-up control
solenoid valve B wire

Faulty lock-up control solenoid

valve B
Disconnected throttle position(TP) sensor connector
Short or open in TP sensor wire
Faulty TP sensor
Disconnected vehicle speed
sensor (VSS) connector
Short or open in VSS wire
Faulty VSS
Short in A/T gear position
switch wire
Faulty A/T gear position switch
Disconnected A/T gear position
switch connector
Open in A/T gear position
switch wire Faulty A/T gear position switch
Disconnected shift control
solenoid valve A connector Short or open in shift control
solenoid valve A wire
Faulty shift control solenoid
valve A
Disconnected shift control
solenoid valve B connector
Short or open in shift control
solenoid valve B wire
Faulty shift control solenoid
valve B
Disconnected countershaft
speed sensor connector
Short or open in countershaft
speed sensor wire Faulty countershaft speed sen-

sor

Disconnected engine coolant
temperature (ECT) sensor
connectorShort or open in ECT sensor
wire Faulty ECT sensor
Blinks

10

9


Blinks
Blinks

8
7
Blinks

6

OFF

Blinks

5

4


Blinks

3


Blinks or OFF Blinks

2

Fails to shift (between 1 st
4th,
2nd
4th or 2nd

3rd

gears only).
Fails to shift (stuck in 4th gear)ProCarManuals.com

If a customer describes the symptoms for codes 3, 6, 11, 14 or 1 5 yet the indicator light is not blinking, it will
be necessary to recreate the symptom by test driving, and then checking the indicator light with the ignition

still
ON.
If the indicator light displays codes 1,2,3,8, 11, or 16, check first the No. 9, 13 and 18 and fuse before elec-
trical troubleshooting.
If any of the fuses have blown, repair them and then recheck. If the indicator light displays codes other than those listed above or stays lit continuously, the TCM is faulty.
Sometimes the indicator light and the Malfunction Indicator Lamp (MID/Check Engine light may come on
simultaneously. If so, check the PGM-FI system according to the number of blinks on the MIL/Check Engine light,
then reset the memory by removing the CLOCK fuse in the main relay box for more than 10 seconds. Drive the vehicle for several minutes at speed over 30 mph (50 km/h), then recheck the MIL/Check Engine light.PGM-FI system

The PGM-FI system on this model is a sequential multiport fuel injectin system.
The indicator light may comes on, indicating a system problem, when, in fact, there is a poor or intermittent
electrical connection. First, check the electrical connections, clean or repair connections if necessary.If the electrical readings are not as specified when using the test harness, check the test harness connections
before proceeding.
Disconnecting the CLOCK fuse also cancels the radio preset stations and the clock setting. Make note of the radio
presets before removing the fuse so you can reset them. If the self-diagnosis indicator light does not blink, perform an inspection according to the table listed below.
Symptom
• Lock-up clutch does not
engage.

• Transmission jerks hard when shifting.
• Transmission jerks hard when
shifting.

• Transmission jerks hard when
shifting

• Lock-up clutch does not

engage.
14-7214-70 14-68
14-67

Refer to

page

Possible Cause
• Disconnected gauge assembly connector
• Short or open in tachometer wire
• Faulty tachometer
• Short or open in FAS (PNK) wire between D16 terminal and

ECM.

• Trouble in ECM
• Disconnected mainshaft speed sensor connector
• Short or open in mainshaft speed sensor wire
• Faulty mainshaft speed sensor
• Disconnected linear solenoid connector
• Short or open in linear solenoid wire
• Faulty linear solenoid
Blinks

OFF

OFF

OFF

When the ignition

switch is turned on,
indicator light
Number of indicator light

blinks while Service CheckConnector is jumped.

11

14

15

16


Ref.page

14-74
14-76
14-77
14-78
NOTE:ProCarManuals.com

Clutch

Reassembly (cont'd)

14. Measure the clearance between the clutch end plate

and top disc with a dial indicator. Zero the dial indicator

with the clutch end plate lowered and lift it up to the

snap ring. The distance that the clutch end plate

moves is the clearance between the clutch end plate

and top disc.

NOTE: Measure at three locations.

End Plate-to-Top Disc Clearance:
15. If the clearance is not within the service limits, select a

new clutch end plate from the following table.

NOTE: If the thickest clutch end plate is installed but

the clearance is still over the standard, replace the

clutch discs and clutch plates.

2ND, 3RD, 4TH and 1ST HOLD CLUTCH

END PLATE
TOP DISC

1ST CLUTCH

PLATE NUMBER

Thickness

END PLATEProCarManuals.com

Self-Diagnosis Function

The EPS control unit monitors the system inputs and outputs, and the driving current of the motor. If there is a problem

in the system, the control unit turns the system off by actuating the relay in the power unit. Power assist stops and

normal manual steering operation resumes. The control unit also turns the EPS indicator light on to alert the driver, and

memorizes the problem in the form of a code. Connecting the terminals of the service check connector with a jumper

wire enables the EPS indicator light to blink the problem code when the ignition switch is turned on.

Unloader Control

If the steering wheel is turned fully and held in the full-lock position, the steering torque reaches the maximum point,

and an over-current flows to the motor and the power unit. The control unit detects this and reduces the current flow

to the motor.

Average Moving Current Control

The electric current flow to the motor is estimated from the current values detected by the current sensor, and the aver-

age current is obtained at two second intervals. The motor driving current is suppressed when the average current value

exceeds a predetermined marginal value. The control unit regurates the motor current during continuous loading to sup-

press any excessive temperature rise in the power unit and the motor.

Over-Voltage Control

If there is an excessive increase in power source voltage due to a poor battery condition, an alternator voltage regulator

problem, etc., the motor assisting force increases, resulting in excessive control. To prevent this, the control unit signals

to the power unit are corrected to ensure that adequate assisting force is generated.ProCarManuals.com

Troubleshooting Procedures

Under normal conditions, the EPS indicator light in the gauge assembly comes on when the ignition switch is turned

to the ON position, then goes off after the engine is started. This indicates that the bulb and its circuits are operating

correctly.

EPS INDICATOR LIGHT

When the EPS control unit senses an abnormality in the system, the control unit memorizes the problem, the EPS indica-

tor light blinks at equal intervals, and the power steering assist is turned off.

When the EPS indicator light has been reported on, connect the two terminals of the service check connector with a

jumper wire. Then turn on the ignition switch and observe the blinking frequency.

SERVICE CHECK

CONNECTOR (BLU)

GRN/WHT

SERVICE CHECK CONNECTOR (BLU)
BLUProCarManuals.com

Fail-Safe Function:

If the control unit detects an abnormality, it shuts the

traction control system off and causes the TCS in-

dicator light to come on. However if the abnormality is

detected while the TCS is activated, the control unit

first establishes the appropriate wheel spin velocity,

then shuts the system down, thus preventing excessive

wheel spin.

Self-Diagnosis Function:

If the control unit detects an abnormality, it records a

Diagnostic Trouble Code (DTC) which can be used to

diagnose the problem. The DTC is shown at the TCS in-

dicator light when the Service Check connector ter-

minals are connected with a jumper wire.

Steering Angle Detection

Steering angle is detected by the steering angle sensor,

located on the steering column. The sensor uses two

magneto-resistor (MR) elements to determine steering

angle and direction of rotation. When the driver turns

the steering wheel, a magnet in the steering shaft

generates waves in the "MR" elements. These waves

are amplified and converted into signals which the con-

trol unit can interpret as angle and direction of turn.

Vehicle Speed Detection

Wheel rotation speed is detected by the wheel sensors,

located at each wheel. The signals are sent to the con-

trol unit, which compares each wheel's speed and de-

termines whether traction control is required.
MR ELEMENT

WHEEL SENSOR
GEAR PULSER
MR

ELEMENT
INDICATOR LIGHTProCarManuals.com

Troubleshooting
TCS Indicator Light

Temporary Driving Conditions:
1. The TCS indicator light will come on and the control unit memorizes the Diagnostic Trouble Code (DTC) under cer-
tain temporary conditions:
2. If the TCS indicator light does not come back on after correcting the tire or tire pressure problem, the TCS system is
OK.

NOTE: Remove the ABS 2.3 (20 A) fuse for at least 3 seconds to clear the DTC from the TCS control unit memory.
TCS Diagnostic Trouble Code (DTC) Indication: 1. Stop the engine.
2. Turn the ignition switch on and confirm that the TCS indicator light comes on.
3. Turn the ignition switch off.
4. Connect the two terminals of the Service Check Connector with a jumper wire.
5. Turn the ignition switch on, but do not start the engine.6. Record the blinking frequency of the TCS indicator light. The blinking frequency indicates the DTC. Long blinks in- dicate the main code: short blinks indicate the sub-code.
7. Refer to the Troubleshooting Guide (page 19-84) for repair information. The spare tire is installed, or a tire of the improper size is installed.
The tire pressures are not correct.
SERVICE CHECK CONNECTOR (BLU)
SERVICE CHECK

CONNECTOR (BLU)
INDICATOR LIGHTProCarManuals.com