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DTC P0121 THROTTLE POSITION CIRCUIT RANGE/PERFORMANCE PROB-
LEM
WIRING DIAGRAM / CIRCUIT DESCRIPTION
[A] : Case of TYPE A is shown (See NOTE)
NOTE:
For TYPE A and TYPE B, refer to NOTE in "ECM VOLTAGE VALUES TABLE" for applicable model.
DTC DETECTING CONDITION
• DTC will set when the following conditions are detected.
• After engine warmed up.
• While vehicle running at specified engine speed.
• No change in intake manifold pressure (constant throttle opening)
• Difference between actual throttle opening (detected from TP sensor)
and opening calculated by ECM (Obtained on the basis of engine
speed and intake manifold pressure) in larger than specified value.
✱2 driving cycle detection logic, continuous monitoring
DTC CONFIRMATION PROCEDURE
WARNING:
• When performing a road test, select a place where there is no traffic or possibility of a traffic acci-
dent and be very careful during testing to avoid occurrence of an accident.
• Road test should be carried out with 2 persons, a driver and a tester, on a level road.
1) Turn ignition switch OFF. Clear DTC with ignition switch ON, check vehicle and environmental condition for :
– Altitude (barometric pressure) : 2400 m, 8000 ft or less (560 mmHg, 75 kPa or more)
– Ambient temp. : –10°C, 14°F or higher
– Intake air temp. : 70°C, 158°F or lower
– Engine coolant temp. : 70 – 110°C, 158 – 230°F
2) Warm up engine to normal operating temperature.
3) Increase vehicle speed to 30 – 40 mph, 50 – 60 km/h in 3rd gear or "D" range and hold throttle valve at that
opening position for 1 min.
4) Stop vehicle.
5) Check DTC in "DTC" mode and pending DTC in "ON BOARD TEST" or "PENDING DTC" mode.
C42 (31P)
9
8
7
6
5
4
3
2
1
21
20
19
18
17
16
15
14
13
12
11
10
31
30
29
28 27
26
25
24
23
22
[B] : Case of TYPE B is shown (See NOTE)
ENGINE GENERAL INFORMATION AND DIAGNOSIS 6-63
GRY/RED
C41-3 [A]
GRY/BLU
C42-16 [B]
ORN
C41 (24P)
7
6
5
4
3
2
1
6
12
16
15
14
13 12
11
10
9
8
24
23
22
21
20
19
18
17
17
ECM
5V
5V
C42-22
C42-10
G02 (17P)
5
4
3
2
1
11
10
9
8
7
16
15
14
13
POSSIBLE CAUSE
• TP sensor malfunction
• High resistance in the circuit
• ECM malfunction
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