1991 ACURA NSX Service Repair Manual

GAUGE ASSEMBLY

EPS INDICATOR LIGHT

UNDER-HOOD FUSE/RELAY BOX

No. 2 (15 A)
IG SW (50 A)

CLOCK (7.5 A)

E-PS
(50 A)

UNDER-DASH FUSE BOX

No. 5 (15 A)ProCarManuals.com

EPS Control Unit Terminal ArrangementProCarManuals.com

3P CONNECTOR (LEFT SIDE)

WIRE SIDE OF FEMALE TERMINALS
VB: Battery voltage

IG SW: Ignition switch

3P CONNECTOR (RIGHT SIDE)

WIRE SIDE OF FEMALE TERMINALS
VB: Battery voltage

IG SW: Ignition switch

6P CONNECTOR

WIRE SIDE OF FEMALE TERMINALS

4P CONNECTOR

WIRE SIDE OF FEMALE TERMINALS
PULSE UNIT 7P CONNECTOR (MT)

WIRE SIDE OF FEMALE TERMINALSProCarManuals.com

Troubleshooting Precautions

EPS Indicator Light

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

the ON (II) position, then goes off after the engine is started. This indicates that the bulb and its circuits are operating cor-

rectly. If there is any trouble in the system, the EPS indicator light turns on during driving, and the power steering assist is

turned off. When the EPS indicator light comes on, the control unit memorizes the DTC. In this case, the control unit does

not activate the EPS system after the engine starts again but it keeps the EPS indicator light on.

Diagnostic Trouble Code (DTC)

• The lowest DTC is indicated first.

• The DTCs continue blinking until the ignition switch is turned off.

• The DTCs are erased from the control unit when the EPS control unit VBU power supply or connector is disconnected.

• The EPS system can be reset and the control unit's memory can be erased by disconnecting the CLOCK (7.5 A) fuse for

more than ten seconds.

Self-diagnosis:

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

1. Turns the EPS indicator light ON to alert the driver.

2. Power assist stops, and normal manual steering operation resumes (except DTC 21 and DTC 33).

3. The EPS control unit memorizes the diagnostic trouble code (DTC).

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

Troubleshooting:

• Before starting the troubleshooting, clear the DTC by disconnecting the CLOCK (7.5 A) fuse for ten seconds or more,

and test-drive the car. Check that the symptom of the trouble appears again, and then troubleshoot. If the problem is an

intermittent problem, the system does not become active after the engine starts even though the problem is solved.

• When both EPS indicator light and A/T "D" indicator light come on, perform the A/T troubleshooting first.

• When the customer's reported problem cannot be verified in the car, ask the customer about the conditions when the

EPS indicator light came ON, then test-drive the car under those conditions, if possible. If the EPS indicator light does

not come ON during the test, check for loose connections or poor contacts at the connectors by wiggling the harness,

etc.

• The connector terminal numbers are viewed from the wire side for the female terminals and from the terminal side for

the male terminals.

• After the repair, test-drive the car and check that the EPS indicator light does not come ON again during the test. (Refer

to the Symptom-to-System Chart for diagnostic period.)ProCarManuals.com

Diagnostic Troubl e Cod e (DTC ) Indicatio n
1. Connec t th e SC S servic e connecto r t o th e servic e chec k connecto r unde r th e glov e box .
SCS SERVIC E CONNECTO R07PAZ - 001010 0
SERVIC E CHEC KCONNECTO R (2P )
2. Tur n th e ignitio n switc h O N (II) , bu t d o no t star t th e engine .
3. Recor d th e blinkin g frequenc y o f th e EP S indicato r light . Th e blinkin g frequenc y indicate s th e diagnosti c troubl e cod e
(DTC) .
NOTE: Chec k th e DT C carefull y an d recor d it . Th e memor y o f th e DT C is erase d i f th e connecto r i s disconnecte d fro m
the EP S contro l unit .
GAUG E ASSEMBL YEPS INDICATO R LIGH T
17-23
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Diagnostic Trouble Code (DTC) Indication

Example:

1.3 seconds
DTC Indication Pattern:

DTC:
11
DTC:
12

EPS Indicator light ON

EPS Indicator light OFF
0.28 seconds

Repeat

Connect the SCS Turn the ignition

service connector switch ON (II)

0.36 seconds 1.3 seconds

• The DTC is 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 DTC.

• The DTCs are repeated sequentially beginning with the lowest number.

4. Remove the SCS service connector.

NOTE: The Malfunction Indicator Lamp (MIL) will stay on after the engine is started if the SCS service connector is

connected.

5. Remove the CLOCK (7.5 A) fuse in the under-hood fuse/relay box for more than 10 seconds to erase the EPS control

unit memory.ProCarManuals.com

Symptom-to-System Char t
Diagnosti c Troubl e Cod e (DTC )
17-27
17-29
17-31
17-3 6
17-38
17-4 0
Initia l diagnosis : Performe d righ t afte r th e engin e start s unti l th e EP S indicato r ligh t goe s off .
Regula r diagnosis : Continuousl y performe d (unde r som e conditions ) afte r th e EP S indicator light goe s of f unti l th e
engin e stops .
Individua l part/syste m diagnosis : Diagnose s a specifi c part/syste m unde r it s operatin g conditions .
ROM : Read-Onl y Memor y
AD C : Analo g Digita l Combate r
PI C : Programb e Interrup t Controle r
RAM : Rando m Acces s Memor y
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Troubleshooting
Hard Steerin g
Steering is heavy .
Star t th e engin e an d chec k th e EP S
indicato r light .
Does th e EP S indicato r ligh t
com e on ? Refe
r t o th e symptom-to-syste m
Char t (se e pag e 17-25 ).
Ar e the y normal ? Correc
t th e ai r pressur e o r whee l
alignment .
Chec k th e powe r assis t wit h th e
ca r parked :
1 . Par k th e vehicl e o n a leve l sur -
fac e wit h th e wheel s pointin g
straigh t ahead .
2 . Measur e th e steerin g whee l
turnin g force . Refe r t o th e char t
on th e right .
Powe r Assis t Chec k wit h Ca r Parked :
Connect a sprin g scal e t o th e steerin g whee l an d tur n th e
wheel . Rea d th e measuremen t whe n th e fron t wheel s star t
to move .
Is i t withi n specification ? Chec
k fo r loos e th e EP S contro l
uni t connector s o r poo r contac t
o f terminals , an d inspec t th e
mechanica l steerin g system :
EP S syste m is OK .
Chec
k th e tir e pressur e an d fron t
whee l alignment .
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