Toyota P0325 User Manual

DI–71

–DIAGNOSTICS ENGINE

DI38A–03

DTC P0325 Knock Sensor 1 Circuit Malfunction

CIRCUIT DESCRIPTION

The knock sensor is fitted to the cylinder block to detect engine knocking. This sensor contains a piezoelec­tric element which generates a voltage when it becomes deformed, which occurs when the cylinder block
vibrates due to knocking. If engine knocking occurs, ignition timing is retarded to suppress it.

DTC No. DTC Detecting Condition Trouble Area

P0325

No knock sensor 1 signal to ECM with engine speed, 2,000
rpm or more

HINT:
If the ECM detects above diagnosis conditions, it operates the fail safe function in which the corrective retard
angle value is set to the maximum value.

WIRING DIAGRAM

S Open or short in knock sensor 1 circuit
S Knock sensor 1 (looseness)
S ECM

ECM

27

E5

KNK1

A09120

W

1

K1
Knock Sensor

1

EB1

A

J1
J/C

A

BR

ED

W

(Shielded)

INSPECTION PROCEDURE

HINT:
Read freeze frame data using T OYOTA hand–held tester or OBD II scan tool. Because freeze frame records
the engine conditions when the malfunction is detected, when troubleshooting it is useful for determining
whether the vehicle was running or stopped, the engine warmed up or not, the air–fuel ratio lean or rich, etc.
at the time of the malfunction.

2000 CELICA (RM744U)

DI–72

–DIAGNOSTICS ENGINE

1 Check continuity between terminal KNK of ECM connector and body ground.

LOCK

PREPARATION:

(a) Remove the ECM cover.
(b) Disconnect the E5 connector of the ECM.

CHECK:

Measure resistance between terminal KNK of the ECM connec­tor and body ground.

OK:

Resistance: 1 MΩ or higher

A09086

KNK1

A09094

OK Go to step 3.

NG

2 Check knock sensor 1 (See page SF–68).

NG Replace knock sensor 1.

OK

3 Check for open and short in harness and connector between ECM and knock

sensor 1 (See page IN–30).

NG Repair or replace harness or connector.

OK

2000 CELICA (RM744U)