FI6929
B05010
B05009
Power Transistor
Platinum Hot Wire
Output Voltage
Temperature Sensor
A
B
B+
Platinum Hot Wire
Temperature Sensor
DI–28
–
DIAGNOSTICS
ENGINE (2RZ–FE, 3RZ–FE)
290
Author:
Date:
2003 TOYOTA TACOMA (RM1002U)
DTC
P0100
Mass or Volume Air Flow Circuit
CIRCUIT DESCRIPTION
The mass air flow meter uses a platinum hot wire. The hot wire air flow meter consists of a platinum hot wire,
temperature sensor and a control circuit installed in a plastic housing. The hot wire air flow meter works in
principle that the hot wire and temperature sensor located in the intake air bypass of the housing detect any
changes in the intake air temperature.
The hot wire is maintained at the set tempreature by controlling the current flow through the hot wire. This
current flow is then measured as the output voltage of the air flow meter.
The circuit is constructed so that the platinum hot wire and temperature sensor can provide a bridge circuit
with the power transistor, and controlled so that the potential of A and B can remain equal in order to maintain
the set temperature.
DTC No.
DTC Detection Condition
Trouble Area
P0100
Open or short in mass air flow meter circuit with more than 3
sec. engine speed 4,000 rpm or less
Open or short in mass air flow meter circuit
Mass air flow meter
ECM
HINT:
After confirming DTC P0100, use the hand–held tester or OBD II scan tool to confirm the mass air flow ratio
from the ”DIAGNOSIS/ENHANCED OBD II/DATA LIST/ALL”.
Mass Air Flow Value (g/s)
Malfunction
Approx. 0
Mass air flow meter power source circuit open
VG circuit open or short
202.2 or more
EVG circuit open
DI12G–13
A14231
From
Terminal 3 of
EFI Relay
(See page DI–206)
M1
Mass Air Flow Meter
L–B
B–W
GR
E7
1
VG
E2
ECM
W–R
3
5
4
E7 EVG
14
22
E7
18
–
DIAGNOSTICS
ENGINE (2RZ–FE, 3RZ–FE)
DI–29
291
Author:
Date:
2003 TOYOTA TACOMA (RM1002U)
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:
Read freeze frame data using the hand–held tester or the OBD II scan tool, as freeze frame data records
the engine conditions when a malfunct