Lexus SC300 / Lexus SC400. Manual - part 903

OK

NG

OK

NG

7

Check fuel pressure.

C

P

(1) Be sure that fuel is enough in tank.

(2) Turn ignition switch on.

(3) Using SST, connect terminals FP and + B of check

connector.

SST 09843–18020

Check that pulsation damper screw rises up when termi-
nals are connected.

Caution:

Never make a mistake with the terminal connection
position as this will cause a malfunction.

Proceed to page 

FI–18

 and continue to troubleshoot.

8

Check for spark.

C

Hint

Disconnect the high–tension cord from the distributor
and, hold the end about 12.5 mm (1/2”) from the ground,
see if spark occurs while the engine is being cranked.

To prevent excessive fuel injected from the injectors dur-
ing this test, Don’t crank the engine for more than 1 – 2
seconds at a time.

Proceed to the page 

IG–6

 and continue to troubleshoot.

Proceed to matix chart of problem systems on

page 

TR–35

.

TR–26

–

ENGINE TROUBLESHOOTING

Basic Inspection

FAIL–SAFE CHART

If any of the following codes is recorded, the ECU enters fail–safe mode.

Code No.

Fail–Safe Operation

Fail–Safe Deactivation Conditions

14

Fuel cut

1 IGF detected in consecutive 3 ignitions.

16

Torque control prohibited.

Returned to normal condition.

22

THW is fixed at 80

°

C (176

°

F).

Returned to normal condition.

24

THA is fixed at 20

°

C (68

°

F).

Returned to normal condition.

31



 Ignition timing fixed at 10

°

 BTDC.



 Injection time fixed

    Starting   9 m sec.

KS input 15 times/sec. or more.

    IDL ON   3.6 m sec.

    IDL OFF   6.7 m sec.

35

Atmospheric pressure is fixed at 101.3 kPa
(760 mmHg 29 92 in Hg)

Returned to normal condition.

(760 mmHg, 29.92 in.Hg).

41

VTA1 is fixed at 0

°

.

The following must each be repeated at least 2

41

VTA1 is fixed at 0

°

.

The following must each be re eated at least 2
time consecutively.

time consecutively.
(w/o TRAC)

(w/o TRAC)
   



  0.1 V ? VTA ? 0.95 V

      0.1 V ? VTA ? 0.95 V
 

  

 IDL : ON

( / TRAC)

(w/ TRAC)

0 25 V ? VTA ? 0 95 V

   



  0.25 V ? VTA ? 0.95 V



IDL : ON

   



  IDL : ON

52

Max. timing retardation.

IG switch OFF.

53

Max. timing retardation.

Returned to normal condition.

55

Max. timing retardation.

IG switch OFF.

Back–Up Function

If there is trouble with the program in the ECU and the ignition signals (IGT) are not output, the ECU controls
fuel injection and ignition timing at predetermined levels as a back–up function to make it possible to continue
to operate the vehicle.

Furthermore, the injection duration is calculated from the starting signal (STA) and the throttle position signal
(IDL). Also, the ignition timing is fixed at the initial ignition timing, 10

°

 BTDC, without relation to the engine speed.

HINT: If the engine is controlled by the back–up function, the ”CHECK” engine warning light lights up to warn
the driver of the malfunction but the diagnostic code is not output.

TR–26

–

ENGINE TROUBLESHOOTING

Fail–Safe Chart

PARTS LOCATION

–

ENGINE TROUBLESHOOTING

Parts location

TR–27

WIRING DIAGRAM

TR–28

–

ENGINE TROUBLESHOOTING

Wiring Diagram