Lexus SC300 / Lexus SC400. Service manual - part 901

DIAGNOSTIC CODE CHART (Cont’d)

TR–18

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ENGINE TROUBLESHOOTING

Diagnostic Code Chart

Trouble Area

”CHECK” 

Engine Warning

Light *

Memory*



See Page

Trouble Area

Normal

Mode

Test

Mode

Memory

See Page

•

Open or short in air flow meter circuit.

•

Air flow meter

•

ECU

ON

N.A.



TR–88

•

ECU

ON

ON



TR–92

•

Open or short in throttle position sensor circuit.

•

Throttle position sensor

ON

ON



TR–94

Throttle  osition sensor

•

 ECU

•

No. 1 speed sensor

•

Combination meter

•

Open or short in No. 1 speed sensor circuit.

•

ECU

ON

ON



TR–98

•

Open or short in starter signal circuit.

•

Open or short in ignition switch or main relay circuit.

•

ECU

N.A.

OFF

X

TR–100

•

Open or short in sub–throttle position sensor circuit.

•

Sub–throttle position sensor

OFF

ON



TR–94

Sub throttle  osition sensor

•

ECU

•

Open or short in No. 1 knock sensor circuit.

•

O en or short in No. 1 knock sensor circuit.

•

No. 1 knock sensor (looseness)

ON

N.A.



No. 1 knock sensor (looseness)

•

ECU



•

 ECU

ON

N.A.

X

TR–102

•

 Open or short in No. 2 knock sensor circuit.

•

 O en or short in No. 2 knock sensor circuit.

•

 No. 2 knock sensor (looseness)

ON

N.A.



 No. 2 knock sensor (looseness)

•

 ECU



*1, 2: See page 

TR–20

.

–

ENGINE TROUBLESHOOTING

Diagnostic Code Chart

TR–19

DIAGNOSTIC CODE CHART (Cont’d)

*1: ”ON” displayed in the diagnosis mode column indicates that the ”CHECK” Engine Warning Light is

lighted up when a malfunction is detected. ”OFF” indicates that the ”CHECK” does not light up during
malfunction diagnosis, even if a malfunction is detected. ”N.A.” indicates that the item is not included
in malfunction diagnosis.

*2: ”O” in the memory column indicates that a diagnostic code is recorded in the ECU memory when a mal-

function occurs. ”X” indicates that a diagnostic code is not recorded in the ECU memory even if a mal-
function occurs. Accordingly, output of diagnostic results in normal or test mode is performed with the
IG switch ON.

*3: Only for USA specification vehicles.

TR–20

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ENGINE TROUBLESHOOTING

Diagnostic Code Chart

Trouble Area

”CHECK”

Engine Warning

Light*

Memory*



See Page

Trouble Area

Normal

Mode

Test

Mode

Memory

See Page

•

 Open or short in EGR step motor circuit.

ON

N A

 O en or short in EGR ste  motor circuit.

•

 ECU

ON

N.A.

•

 Open in EGR gas temp. sensor circuit.

ON

ON



TR–108

 O en in EGR gas tem . sensor circuit.

•

 ECU

ON

ON

•

 Open or short in fuel pump ECU circuit.

•

 Fuel pump ECU

•

 Engine & ECT ECU power source circuit.

•

 Fuel pump

•

 Engine & ECT ECU

ON

ON



TR–114

•

 A/C switch circuit

•

 Throttle position sensor IDL circuit

•

 Neutral start switch circuit.

•

 Accelerator pedal and cable

•

 ECU

N.A.

OFF

X

TR–118

*4:

This indicates items for which ”2 trip detection logic” is used. With this logic, when a logic malfunction is
first detected, the malfunction is temporarily stored in the ECU memory. If the same case is detected again
during the second drive test, this second detection causes the ”CHECK” Engine Warning Light to light up.
The 2 trip repeats the same mode a 2nd time. (However, the IG switch must be turned OFF between the
1st trip and 2nd trip).
In the Test Mode, the ”CHECK” Engine Warning Light lights up the 1st trip a malfunction is detected.

–

ENGINE TROUBLESHOOTING

Diagnostic Code Chart

TR–21