P0502
Read the instructions below then
start the fault diagnostic procedure.
Symptom: CHECK ENGINE.
Cruise control not working.
Low engine torque on cars with manual gearbox.
Vehicle Speed. No input signal.
Fault symptoms
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Cruise control not working.
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Low engine torque on cars with manual gearbox.
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On-Board Diagnostics
Type of diagnosis:
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Continuous. But interrupted when fault criteria fulfilled and will not restart until next driving cycle.
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Enable criteria:
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Engine running. Coolant temperature exceeds 60°C. Engine speed above 1750 rpm. Load above 335 mg/c. Brake pedal not depressed.
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Fault criteria:
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No vehicle speed for more than 5 s.
Then, 17 minutes without the vehicle speed leaving 0. On automatic cars, the selector lever must also have another value than P or N. Enable criteria for these two fault criteria need not be fulfilled.
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Dependents
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System reaction to a fault:
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Cruise control is blocked. Vehicle speed (Bus from MIU) is used as a substitute value. The idling adaptation is blocked and reset.
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OK report:
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60 sec has expired since start. Vehicle speed has exceeded 0 on some occasion.
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Fault handling:
(See “Fault diagnosis, general” for more information.)
Diagnostic help
Fault diagnosis concerns electrical faults in connecting cables to ABS (check first whether there is a fault in ABS or TC/ABS). Communication with Trionic is via the P-bus if the car is equipped with TC/ABS. For further information on fault diagnosis of bus communication with TC/ABS, see
Fault diagnosis strategy for electronic systems
. DTC P1625 will be generated if TC/ABS is missing from the bus, see
P1625
.
Functions in the diagnostic tool related to the fault:
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Diagnostic status for the diagnosis.
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Vehicle speed (Lead from ABS, alternatively bus from TC/ABS), unit km/h.
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See also description of
Menu "Read Values"
for more information.
Checking the wiring
Jiggle the wiring harness at several points and in different directions to detect intermittent breaks and short circuits. Observe the multimeter, diagnostic tool or test lamp during the check.
