1995 ACURA TL Speedometer

Troubleshooting

Troubleshooting Procedures (cont'd)

ECM Data

By connecting the OBD II scan tool or the Honda PGM Tester to the 16P data link connector (DLC), various data can be

retrieved from the ECM. The items listed in the table below conform to the SAE recommended practice.

The Honda PGM Tester also reads data beyond that recommended by SAE.

Understanding this data will help to find the causes of intermittent failures or engine problems.

NOTE:

• The "operating values" given below are approximate values and may be different 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 posi-

tion or , and the A/C and all accessories turned off.

Data
Description
Operating Value

Freeze Data

Diagnostic

Trouble Code

(DTC)
If the ECM 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.

Engine Speed

The ECM computes engine speed from the signals sent

from the Crankshaft Position sensor.

This data is used for determining the time and amount

of fuel injection.
Nearly the same as

tachometer indication

At idle speed:

700 ± 50 rpm

Vehicle Speed

The ECM converts pulse signals from the Vehicle

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

speedometer indication

Mass Air

Flow (MAF)
The MAF sensor measures the volume of the air that

flows into the engine, and sends voltage signals to the

ECM.
At idle speed:

2.2 - 4.4 g/sec

At 2,500 rpm with not

load:

7.5- 13.0 g/sec

Engine Coolant

Temperature

(ECT)
The ECT sensor converts coolant temperature into

voltage and signals the ECM. The sensor is a thermistor

whose internal resistance changes with coolant

temperature. The ECM 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:

90 - 96°C

Heated Oxygen

Sensor (HO2S)

(Primary)

(Secondary)
The Heated Oxygen Sensor detects the oxygen content

in the exhaust gas and sends voltage signals to the

ECM. Based on these signals, the ECM 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 stoichio-

metric ratio), the voltage signal is higher.
0.0-1.25V

At idle speed:

about 0.1-0.9VProCarManuals.com

Gauge/Terminal Locatio n Inde x
CONNECTO R "A " (C612 )
CONNECTOR "B " (C613 )
FUE L GAUGE :
Gaug e Test , pag e 23-12 1
Sendin g Uni t Test , pag e 23-12 2 ENGIN
E COOLAN T TEMPERATUR E (ECT ) GAUGE :
Gaug e Test , pag e 23-12 4
Sendin g Uni t Test , pag e 23-12 4
SPEEDOMETER :Indicates 6 0 mp h a t 102 5 rp m(60 km/ h at 63 7 rpm ) of th evehicl e spee d senso r (VSS) .
CONNECTO R "D " (C615 ) CONNECTO
R "C " (C614 )
SAFET
Y INDICATO R
Se e pag e 23-13 5
TACHOMETER :Indicates 10 0 rp m a t
25 0 pulse s pe r minut e
of th e ignitio n contro lmodule (ICM) .
A/
T GEA R POSITIO N
INDICATO R SYSTE M
Se e pag e 23-14 2
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Speedometer/Trip Meter/Odometer

Troubleshooting

NOTE:

The numbers in the table show the troubleshooting sequence.

If necessary, replace the speedometer, trip meter, and odometer as a unit.

VSS Input Test

Trml

Wire
Test condition
Test: Desired result
Possible cause if result is not obtained

1

2

3
BLK

YEL

ORN
Under all conditions

Ignition switch ON (II)

Ignition switch ON (II)
Check for continuity to ground:

There should be continuity.

Check for voltage to ground:

There should be battery voltage.

Check for voltage to ground:

There should be about 5 V or more.
• Poor ground (G101)

• An open in the wire

• Blown No. 1 (10 A) fuse in the

under-dash fuse/relay box

• Short to ground

• An open in the wire

• Short to ground

• An open in the wire

NOTE: A short to ground in the ORN wire can be caused by a short in any component connected to it.ProCarManuals.com

Vehicle Spee d Senso r (VSS )
Troubleshootin g
Speedometer, tri p meter , an d odomete r d o no t work .
Befor e testing , inspec t th e No . 1 (1 0 A ) fus e in th e under-das h fuse/rela y box .
TEST HARNES S
07LA J - PT3020 A
RED TES T HARNES S
CLIP
PROTECTIV ETAPE
VSS
Is ther e continuity ?Repair ope n i n th e BL K wir ebetwee n th e VS S an d G101 .GRN TES T HARNES S
CLI P
TES T HARNES S
07LA J - PT3020 A
Tes t th e YE L wire :
1 . Connec t th e othe r tes t harnes s
connecto r t o th e VSS .
2. Connec t th e WH T tes t harnes sclip t o th e positiv e prob e o f avoltmeter , an d connec t th e RE D
tes t harnes s cli p t o th e negativ e
probe.3. Tur n th e ignitio n switc h O N (II) .
RED TES T HARNES S
Is ther e batter y voltage ?Repair ope n i n th e YE L wir ebetwee n th e VS S an d th e under -dash fuse/rela y box .VSS
PROTECTIV ETAPE
WH T TES T HARNES S CLI P
(T o pag e 23-119 )
Tes
t th e BL K wire :
1. Disconnec t th e 3 P connecto rfrom th e vehicl e spee d senso r(VSS).2. Connec t th e tes t harnes s onl yto th e engin e wir e harness .3. Connec t th e RE D tes t harnes sclip to th e positiv e prob e o f a nohmmeter .4. Chec k fo r continuit y betwee nthe RE D tes t harnes s cli p an dbod y ground .
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(From pag e 23-118 ) TES
T HARNES S
07LA J - PT3020 A
Tes t th e OR N wire :
Connec t th e GR N tes t harnes s
clip t o th e positiv e prob e o f avoltmeter , an d connec t th e RE D
tes t harnes s cli p t o th e negativ e
probe .
I s ther e abou t 5 V or more ? Repai
r ope n o r shor t i n th e OR N
wir e betwee n th e VS S an d ECM ,
transmissio n contro l modul e
(TCM) , an d cruis e contro l unit .
Tes t th e VSS :
1. Tur n th e ignitio n switc h OFF .2. Rais e th e fron t o f th e car , an d
suppor t i t wit h safet y stands .
3. Pu t th e ca r i n neutra l wit h th eignitio n switc h O N (II) .4. Slowl y rotat e on e whee l wit h
th e othe r whee l blocked .
VSS
GR N TES T HARNES S CLI P
Doe s voltag e puls e fro m 0 to
approx . 5 V or more ? Replac
e th e VS S (se e pag e
23-120 ).
Tes t th e Speedometer :
1 . Disconnec t th e 16 P connecto r
"A " (C612 ) fro m th e gaug e
assembly .
2 . Connec t a voltmete r betwee n
the OR N wire , an d bod y ground .3. Slowl y rotat e on e whee l wit hthe othe r whee l blocked . GAUG
E ASSEMBL Y 16 P CONNECTO R "A " (C612 )
WIR E SID E O F
FEMAL E TERMINAL S
Doe s th e mete r indicat e puls -
in g voltag e ( 0 to approx . 5 V
o r more) ? Repai
r ope n i n th e OR N wir e
betwee n th e VS S an d th e speed -
ometer .
Replac e th e speedometer .
PROTECTIVETAPE
RED TES THARNES SCLIP
WH T TES T HARNES SCLIP
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