T8 / P0638 00
Read the instructions below then
start the fault diagnostic procedure.
Symptom: Fault indicator lamp (for further information see WIS Fault diagnosis, general)
Limp home
Throttle Mechanical, Throttle Position Deviation from Demanded
Fault symptom
Fault indicator lamp (for further information see WIS Fault diagnosis, general)
Limp home
On-board diagnosis
Type of diagnosis:
Enable criteria:
| Throttle position not requested in rest position (position regulated by Trionic 8). |
Fault criteria:
| When current throttle position deviates 10% from the requested position. |
Dependent:
System reaction to a fault:
| Correction of mass air flow/combustion for fuel calculation is blocked. |
| Limited acceleration and idle function. |
| Secondary air switched off. |
OK report:
| Fault criterion not fulfilled and vehicle speed over 0 km/h for more than 60 s. |
Fault handling:
| (See section Fault handling III, "Other emission-related components and functions" for more information.) |
Checking the wiring harness
Move the wiring harness at several spots and in several directions to reveal intermittent breaks and short-circuits. Check switches, connectors and crimp connections for oxidation, retracted pins and pin clamping force.
Diagnostic help
Diagnosis regards:
| Electrical fault in connecting leads or component. |
| Mechanically binding/affected throttle. |
| Approximately 3 to 5 seconds after Ignition on and non-actuated accelerator pedal, the throttle resumes rest position to conserve current. |
Functions in the diagnostic tool related to the fault:
| • | Throttle Position Sensor 1 |
| • | Throttle Position Sensor 2 |
| (See also description of readings/activations in diagnostic tool) |
