DTC 1-1-2

Diagnostic Trouble Code (DTC) Information







Special Tools: 998 8686

Condition
Data about the vehicle speed is sent from the combined instrument panel to the cruise control control module.

The signal is an homogenous rectangular wave with a variable frequency; the frequency increases with vehicle speed.

The control module uses the signal as a reference speed when setting and checking the speed. The signal is also used to determine whether the variations in speed are normal.

The control module has an internal function which can disengage the cruise control for safety reasons.

This function is activated if acceleration or deceleration is abnormal (wheel-spin) or (wheel lock-up) and when vehicle speed is less than 75 % of the set speed when driving up steep hills, when the engine cannot maintain a constant speed.

However, disengagement of the cruise control for safety reasons does not necessarily mean that it is not functioning correctly.

Diagnostic trouble code (DTC) 1-1-2 is stored if the cruise control has been disengaged for safety reasons due to an incorrect speed signal.

The diagnostic trouble code (DTC) is only generated if the control module has detected a normal road speed signal at some point during the test drive.

Possible source

An abnormal vehicle speed signal can be caused by:
- Incorrect installation or poor suppression of accessories connected to the same vehicle speed signal or same ground terminal as the speedometer.
- different ground terminals for the control module and the combined instrument panel
- short-circuit to ground or voltage in the signal cable from the combined instrument panel
- intermittent open-circuit in the signal cable from the combined instrument panel
- defective speedometer
- contact resistance in the terminals.

Fault symptom[s]
- The cruise control is disengaged while the car is being driven.
- The speedometer displays an incorrect value.