
MPI –
Troubleshooting
13-8
3. INSPECTION CHART FOR DIAGNOSIS CODES
Code No.
Diagnosis item
Reference page
12
Air flow sensor system
13-8
13
Intake air temperature sensor system
13-9
14
Throttle position sensor system
13-9
21
Engine coolant temperature sensor system
13-10
22
Crank angle sensor system
13-11
23
Camshaft position sensor system
13-12
24
Vehicle speed sensor system
13-13
25
Barometric pressure sensor system
13-14
31
Detonation sensor system
13-15
41
Injector system
13-15
44
Ignition coil and power transistor unit system
13-16
64
Alternator FR terminal system
13-17
INSPECTION PROCEDURE FOR DIAGNOSIS CODES
Code No. 12 Air flow sensor system
Probable cause
Range of Check
D
Engine speed is 500 r/min or more.
Set conditions
D
Sensor output frequency is 3 Hz or less for 4 seconds.
D
Malfunction of the air flow sensor
D
Improper connector contact, open or short-circuited
harness wire of the air flow sensor
D
Malfunction of the engine-ECU
Measure at the air flow sensor con-
nector A-25.
D
Connect the connector. (Use
the test harness: MB991709)
1. Voltage between 3 and earth
(Engine: Idling)
OK: 2.2– 3.2 V
2. Voltage between 7 and earth
OK: 0 – 1 V (Engine: idling)
6 – 9 V (2,000 r/min)
OK
Replace the engine-ECU.
1. NG
Check the air flow sensor circuit.
(Refer to P.13-55, INSPECTION
PROCEDURE 48.)
2. NG
Measure at the engine-ECU con-
nector B-59.
D
Connect the connector.
D
Voltage between 19 and earth
(Ignition switch: ON)
OK: 6 – 9 V
OK
Check the following connector:
B-59
OK
Check trouble symptom.
NG
Replace the engine-ECU.
NG
Check the following connector:
A-25
NG
Repair
OK
Check trouble symptom.
NG
NG
Repair
Replace the air flow sensor.