Mazda MX-6 1998, Workshop Manual

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TROUBLESHOOTING [ENGINE CONTROL FS]
DTC P1120 TP sensor out of range low
DESCRIPTION
• DTC P1120 indicates throttle position (TP) signal within the self-test range but with closed
throttle position range of below 0.17 volts
[Possible Cause]
• Frayed wires • Damaged TP sensor
• Corrosion on TP sensor, PCM or harness connectors • Damaged PCM
• Constant voltage circuit harness open or shorts
STEP INSPECTION ACTION
1 CHECK FRAYED TP CIRCUIT WIRES OR
CORROSION ON CONNECTORS
• Do complete visual inspection of harness
connector at TP sensor (including pins) for
corrosion.
• Do complete visual inspection of harness
wires between TP sensor and PCM for
insulation fraying and corrosion.
• Is a fault present?
Yes SERVICE as necessary.
RESET PCM to completely clear DTCs.
tr After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
No
Go to next step.
2 CHECK FOR STUCK TP SENSOR
• Key on, engine off.
• Access TP V PID with NGS tester.
• Slowly move throttle from closed throttle
position to wide open throttle and observe
TP V PID.
• While opening throttle, is TP V PID
below 0.49 volts?
Yes Go to next step.
No Go to DTC P1125 (Continuous).
3 CHECK CONSTANT VOLTAGE CIRCUIT
VOLTAGE
• Key off.
• TP sensor disconnected.
• Key on, engine off.
• Measure voltage between constant voltage
circuit and TP sensor ground circuit at TP
sensor vehicle harness connector.
• Is voltage between 4.0 and 6.0 volts?
Yes Go to next step.
No
Key off.
RECONNECT all components.
REPAIR open in constant voltage circuit.
4
CHECK TP SENSOR CIRCUIT CONTINUITY
• Key off.
• TP sensor disconnected.
• Disconnect PCM. Inspect for damaged or
pushed out pins, corrosion, loose wires,
etc. Service as necessary.
• Install breakout box. Leave PCM
disconnected.
• Measure resistance between TP circuit at
TP sensor connector and Test Pin 89 at
breakout box.
• Is resistance less than 5.0 ohms?
Yes TP SIG harness circuit to PCM is okay.
Go to next step.
No SERVICE corrosion or open in TP sensor signal circuit
harness.
RESET PCM to completely clear DTCs.
c r After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
5 CHECK TP SENSOR SIGNAL TO PCM
• Key off.
• Connect PCM to breakout box.
• Connect TP sensor.
• Start engine and idle for 2 minutes.
• Measure the voltage between Test Pin 89
and Test Pin 91 at breakout box while
slowly opening throttle from closed
position.
• Is voltage between 0.17 to 0.49 volts?
Yes TP sensor is damaged.
REPLACE TP sensor.
REMOVE breakout box.
RERUN OBD Test.
No RERUN OBD Test.
If DTC P1120 is still present, go to DTC P1125
(Continuous).
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