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. Engine speed above 1750 rpm. Load above 480 mg/c. Brake pedal not depressed. Coolant temperature exceeds 60°C.
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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:
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 s has expired since start. Vehicle speed has exceeded 0 on some occasion.
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Fault handling:
(See section
Fault handling III, other emission-related components and functions
for more information.)
Diagnostic help
Fault diagnosis concerns electrical faults in connecting lead to ABS (ABS or TC/ABS are checked for faults first). If the car is equipped with TC/ABS, communication with Trionic will take place through the P-bus. For further information on fault diagnosis of bus communication with TC/ABS, see
Fault diagnosis strategy for electronic systems
. If TC/ABS is absent from the bus, diagnostic trouble code P1925 will be generated, see
P1925
.
Functions in the diagnostic tool related to the fault:
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Diagnostic status for the diagnosis.
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Vehicle speed (Leads from ABS, alternatively bus from TC/ABS.), unit km/h.
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See also the description of readings under
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.
