Throttle control: Diagnostics
- DTC P1230 is generated if there is a fault in the circuit to any of the throttle position sensors. The software has been changed during MY02 in order to make the diagnosis less sensitive to disturbances that normally occur. It is therefore essential that the throttle body is not changed if the control module is programmed with the old software version. See FAULT DIAGNOSIS for more information.
- DTC P1231 is generated after intermittent breaks in the circuit to one of the throttle position sensors normally caused by contaminants on the potentiometer surfaces. See FAULT DIAGNOSIS for more information.
- If a throttle motor fault or a mechanical fault should occur, diagnostic trouble codes P1240, P1251-P1253, P1260-P1261, P1263 or P1264 will be generated.
- If an internal control module fault that affects the throttle control should occur, diagnostic trouble codes P1601-P1611, P1613-P1614 or P1621 will be generated.
- If there is an open circuit or short circuit on the control module output to the limp-home solenoid relay, diagnostic trouble code P1670-P1671 will be generated.
Most of the above faults will put the throttle control into limp-home mode.
IMPORTANT:
When the throttle control system is in limp-home mode, the fault is stored in the control module memory. Each time the ignition is switched on, the limp-home solenoid is activated for 1 s and then for 4 x 0.5 s to ensure that the mechanism is not reset before the fault has been rectified. Repair work must therefore be carried out in the following order:
If this sequence is not followed, it is highly likely that the car will leave the workshop with the throttle control system still in limphome mode. When the system detects that it is in mechanical limp-home mode, diagnostic trouble code P1260, P1263 or P1251 will be generated.
Silicone sprays must not be used on the electrical or mechanical parts of the throttle body.
The throttle body must not be washed.
- Rectify the fault.
- Delete the DTCs.
- Reset the limp-home mechanism.
If this sequence is not followed, it is highly likely that the car will leave the workshop with the throttle control system still in limphome mode. When the system detects that it is in mechanical limp-home mode, diagnostic trouble code P1260, P1263 or P1251 will be generated.
Silicone sprays must not be used on the electrical or mechanical parts of the throttle body.
The throttle body must not be washed.