Toyota Celica 2005 Repair Manual page 34

Fig. 4
0V
Sensor
C
B
5V
1
2
Fig. 5
C SHORT
1
2
Fig. 6
C
Sensor
1
2
2005 CELICA (RM1131U)
INTRODUCTION
5V
A
5V
1 1
2 2
Z17007
B A
1 1
2
2
Z17008
ECU
B
A
1 1
2 2
Z17009
− HOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
(b) Check the voltage.
In a circuit in which voltage is applied (to the ECU connec-
tor terminal), an open circuit can be checked for by con-
ducting a voltage check.
As shown in Fig. 4, with each connector still con-
nected, measure the voltage between body ground
and terminal 1 of connector "A" at the ECU 5V out-
put terminal, terminal 1 of connector "B", and termi-
nal 1 of connector "C", in that order.
If the results are:
5V: Between Terminal 1 of connector "A" and Body Ground
5V: Between Terminal 1 of connector "B" and Body Ground
0V: Between Terminal 1 of connector "C" and Body Ground
Then it is found out that there is an open circuit in the wire har-
ness between terminal 1 of "B" and terminal 1 of "C".
7. CHECK SHORT CIRCUIT
If the wire harness is ground shorted as in Fig. 5, locate the sec-
tion by conducting a "continuity check with ground".
Check the continuity with ground.
(1) Disconnect connectors "A" and "C" and measure
the resistance between terminal 1 and 2 of connec-
tor "A" and body ground.
In the case of Fig. 6:
Between terminal 1 of connector "A" and body
ground → Continuity (short)
Between terminal 2 of connector "A" and body
ground → No continuity
Therefore, it is found out that there is a short circuit
between terminal 1 of connector "A" and terminal 1
of connector "C".
33
IN−33