Toyota T100 1996, Service Manual, Page: 530 / 2062

N09214
DI − 266
− DIAGNOSTICS AUTOMATIC TRANSMISSION
1996 TOYOTA T100 (RM449U)
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The diagnosis system operates in normal mode
during normal vehicle use, and also has a check
mode for technicians to simulate malfunction symp-
toms and perform troubleshooting. Most DTCs use
2 trip detection logic(*) to prevent erroneous detec-
tion. By switching the ECM to check mode when
troubleshooting, the technician can cause the MIL
to light up and for a malfunction that is only detected
once or momentarily (TOYOTA hand
− held tester)
(See page DI − 265 ).
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*2 trip detection logic:
When a logic malfunction is first detected, the mal-
function is temporarily stored in the ECM memory.
If the same malfunction is detected again during the
2nd test drive, this 2nd detection causes the MIL to
light up.
(b) Inspect the DLC3.
The vehicle’s ECM uses the V.P.W. (Variable Pulse Width)
for communication to comply with SAE J1850. The termi-
nal arrangement of DLC3 complies with SAE J1962 and
matches the V.P.W. format.
Terminal No. Connection / Voltage or Resistance Condition
2 Bus
ę
Line / Pulse generation During communication
4 Chassis Ground
↔
Body / 1
Ω
or less Always
5 Signal Ground ↔ Body / 1 Ω or less Always
16 Battery Positive ↔ Body / 9 − 14 V Always
HINT:
If your display shows ”UNABLE TO CONNECT TO VEHICLE”
when you have connected the cable of OBD II scan tool or TOY-
OTA hand
− held tester to DLC3, turned the ignition switch ON
and operated the scan tool, there is a problem on the vehicle
side or tool side.
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If communication is normal when the tool is connected to
another vehicle, inspect DLC3 on the original vehicle.
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If communication is still not possible when the tool is con-
nected to another vehicle, the problem is probably in the
tool itself, so consult the Service Department listed in the
tool’s instruction manual.