Z17007
Fig. 4
Sensor
2
1
A
C
1 1
2
2
B
5V
5V
5V
0V
Z17008
Fig. 5
2
1
A
C
1
1
2
2
B
SHORT
Z17009
Fig. 6
2
1
A
C
1
1
2
2
B
Sensor
ECU
−
INTRODUCTION
HOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
IN
−
31
1996 LAND CRUISER (RM451U)
(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”.
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Version 1.00 - 12/21/2010
