P1759

Symptom: "CHECK ACS" warning lamp on. The system's emergency program has been activated. Engagement takes place depending on the current engine rpm and at a higher engine speed than usual (compared with when a throttle position signal is present).

P1759

Connect the Scan tool diagnostics instrument and check whether there are any diagnostic trouble codes in the Trionic system.

Are any of fault codes P0120 - P0123 present?

yes

Rectify as described in "Trionic engine management system" and continue with point 3.

no

Continue with point 2.

2 Check the throttle position signal

Warning If there is a throttle position sensor fault, the Sensonic system could set the clutch to the engagement position as soon as 1st, 2nd or reverse gear is selected, causing the car to move off.

Unplug the Sensonic system's control module and connect a multimeter set for frequency measurement to pins 12 and 19. With the ignition switch in the ON position, a frequency reading of 100 Hz should be obtained.

Is the reading correct?

yes

Continue with point 3.

no

Repair or replace the lead in question and proceed to point 3.

3 Final check

-	Clear the diagnostic trouble code.

-	Perform a drive cycle by driving the car at varying engine rpm and loads for 5 minutes.

-	Check whether the diagnostic trouble code has recurred.

Has the diagnostic trouble code recurred?

yes

Continue as described in the section "Before replacing a control module", see .

no

The steps taken to rectify the fault were correct.