Mazda MX-6 1998, Workshop Manual

Page: 52 / 1282

TROUBLESHOOTING [ENGINE CONTROL FS]
DTC P0122 TP sensor circuit low input
DESCRIPTION
• DTC P0122 indicates Throttle Position (TP) Sensor signal is less than self-test minimum
value of 3.43% (0.17 volts)
[Possible Cause]
• TP not seated properly (tightened down)
• Damaged TP sensor
• Open TP signal circuit or constant voltage harness
• TP signal circuit harness short to ground
• Damaged PCM
STEP INSPECTION
ACTION
1 DTC P0122 ATTEMPT TO GENERATE
OPPOSITE DTC P0123
• Key off.
• Disconnect TP sensor. Inspect for
damaged or pushed out pins, corrosion,
loose wires, etc. Service as necessary.
• Leave TP sensor disconnected.
• Jumper constant voltage circuit to TP
signal circuit at TP sensor vehicle harness
connector.
• Key on, engine off.
Yes TP signal circuit shorted to TP sensor ground circuit in TP
sensor, or TP signal circuit or constant voltage circuit open
in TP sensor.
REPLACE TP sensor.
REMOVE jumper.
RERUN OBD Test.
Note
• If any NGS tester communication problem
exists, remove jum per and go directly to
step 4
No
Constant voltage circuit or TP signal circuit open in
harness or PCM or TP signal circuit shorted to ground
circuit in harness or PCM.
REMOVE jumper.
Go to next step.
• Access TP V PID with NGS tester.
• Is TP V PID greater than 4.79 V?
• Is DTC P0123 present (ignore all other
DTC’s)?
2 CHECK CONSTANT VOLTAGE
• Key off.
• TP sensor disconnected.
• Key on, engine off.
• Measure voltage between constant voltage
circuit and 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.
3
CHECK TP SIGNAL 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
the TP sensor vehicle harness connector
and Test Pin 89 at breakout box.
• Is resistance less than 5.0 ohms?
Yes TP signal harness circuit to PCM is okay.
Go to next step.
No SERVICE open in TP signal harness circuit.
REMOVE breakout box.
RECONNECT all components.
RESET PCM to completely clear DTCs.
cr After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
4 CHECK TP SIGNAL CIRCUIT FOR SHORTS
TO PCM GROUND (BETWEEN PCM AND TP
SENSOR GROUND CIRCUIT) OR GROUND
• Key off.
• TP sensor disconnected.
• PCM disconnected.
• Measure resistance between Test Pin 89
and Test Pins 91 and 24 or 103 at breakout
box.
Yes TP signal circuit open or shorted to PCM ground (ground
circuit) in PCM.
REPLACE PCM.
REMOVE breakout box.
RECONNECT all components.
RESET PCM to completely clear DTCs.
o ’ After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
• Is each resistance greater than 10,000
ohms?
No
SERVICE TP signal circuit shorted to PCM ground
(ground circuit) in harness.
REMOVE breakout box.
RECONNECT all components.
RESET PCM to completely clear DTCs.
o ’ After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
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