Hello problem

[Dan Evans]

Problem with cruise control not working have code come up U040581
Thanks Dan

 

[Mike1alike]

Hello, Dan!'Welcome to the forum!

 

[Mike1alike]

U0405 usually means the ECU is receiving invalid data from the cruise control system rather than the cruise unit itself failing. On many Fiats this can be caused by the cruise control switch, the steering wheel clock spring, or sometimes the brake pedal switch (as the ECU cancels cruise if it thinks the brake is applied). It would be worth checking the brake switch operation and the steering wheel controls/clock spring first.

 

[Dan Evans]

Hi Mike
Can I ask what/where the clock spring would be?
Aliso, the brake pedal switch- is this just one switch or are there two cos the brake lights are working fine

 

[Mike1alike]

The clock spring (also called the steering wheel spiral cable) is a ribbon cable assembly located behind the steering wheel, under the airbag. It allows the electrical connections for things like the airbag, horn and steering-wheel buttons to keep working while the wheel turns left and right.
If the ribbon cable inside breaks or develops a bad contact, the cruise control buttons on the steering wheel may stop working even though everything else seems normal.
Regarding the brake pedal switch, many Fiats actually use two circuits inside the same switch. One circuit operates the brake lights, and the other sends a signal to the ECU/cruise control system.
So it’s possible for the brake lights to work normally while the cruise control still sees a fault if the second circuit inside the switch is faulty or misadjusted.

 

[Mike1alike]

This is what the clock spring looks like (it sits behind the steering wheel under the airbag):

Clock spring in a car: problems, symptoms, replacement cost

What is a clock spring in a car, problems, symptoms of a failed coil spring, replacement cost

www.samarins.com

 

[Dan Evans]

Thanks Mike