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[terry paget]

2008 Astra petrol 1.6 manual
Daughter's car went into a garage in London for thermomost replacement  to correct a warning light on. Thermostat is replaced, warning light is off, but she reports the horn soes not work now.
Please advise.

[dave the builder]

Check the basics first
ground and switched live at the horn
could just be the button or simple fault BUT the astra H has had issues with CIM failure which manifests as no horn working IIRC

some info won't be covered by any warranty now though 12 years down the line .

do you still have the astra parts car ? though the CIM (if it's the issue) would require programming ,which requires security pass 

[terry paget]

Astra parts car  has been scrapped. What is the CIM?
Check the basics first
ground and switched live at the horn
could just be the button or simple fault BUT the astra H has had issues with CIM failure which manifests as no horn working IIRC

some info won't be covered by any warranty now though 12 years down the line .

do you still have the astra parts car ? though the CIM (if it's the issue) would require programming ,which requires security pass 

[VXL V6]

Column Integrated Module 

[Marks DTM Calib]

It should have a metal clip on it, if not its worth fitting one

But the first thing to do is measure at the horn to see if its getting volts

[terry paget]

This is the third Astra I have owned that has suffered a failed horn, seems to be a common fault. On my first Astra (died of a seized engine during MOT) a forum member kindly posted  instructions for changing changing the CIM; I began to do it on my donor car, but lost interest. Is it a big job?

[STEMO]

This is the third Astra I have owned that has suffered a failed horn, seems to be a common fault. On my first Astra (died of a seized engine during MOT) a forum member kindly posted  instructions for changing changing the CIM; I began to do it on my donor car, but lost interest. Is it a big job?

Not only did you lose interest, you actually forgot what a CIM is 

[Doctor Gollum]

Google it carefully... 

[terry paget]

This morning this car would not start. Daughter Catherine rang the RAC, when the man arrived, he opened the bonnet, and immediately spotted the fault - not connected, he said - reconnected it (battery lead presumably) engine then started. The RAC man had a quick look at the horn, but could not see any obvious fault.

She had a local garage change the thermostat recently to extinguish a warning light, I guess they left they battery lead loose.
After their repair Catherine noticed the horn did not work. She is taking the car back to them tomorrow to check the horn. It sounds horribly like the CIM, doesn't it? Browsing Amazon I have found information, and some ebay videos. I read there were recalls. On e-bay new CIMs cost £185 and used ones less. Have any members done it? Some videos change the CIM, others clean the contacts.

[dave the builder]

could just be the horn button or loose connection ,bad earth
if it is the CIM do you have the car pass ?
in theory ...I don't see an issue with fitting a push button on the dash for a horn 
if the horn not working is the only issue
I've never had to replace a CIM ,DOH ! just jinxed myself 

[terry paget]

I see no reason why a push button on the dash, labelled HORN, should not suffice either. There is no other fault. Or either on the centre console.

[dave the builder]

Or a tassel hanging from the roof ,connected to a massive air horn  ,like a train or lorry 

Don't think I've ever used a car horn for it's intended purpose
i'm usually hammering the brakes or GO pedal and steering to get the **** out the way 
but a working horn is a requirement of the MOT test

[Marks DTM Calib]

I will say it, this is crap advice from all, you must go through basic diag before deciding what the fault is.

You must check for volts at the horn and work back.

Diving in with 'its the CIM' is going down the road that bad mechanics do..........plus the CIM failure impacts more than just the horn (as its a connection inside that has the issue, hence why metal clips were fitted.....)

And Dave...........an earth on a car, really 

[Nick W]

I will say it, this is crap advice from all, you must go through basic diag before deciding what the fault is.

You must check for volts at the horn and work back.

Diving in with 'its the CIM' is going down the road that bad mechanics do..........plus the CIM failure impacts more than just the horn (as its a connection inside that has the issue, hence why metal clips were fitted.....)

Absolutely right.


Not only is easier, quicker and more likely to find the fault than immediately blaming the complicated thing you don't understand, but it tends to be cheaper too.

[dave the builder]

I will say it, this is crap advice from all, you must go through basic diag before deciding what the fault is.

You must check for volts at the horn and work back.

Diving in with 'its the CIM' is going down the road that bad mechanics do..........plus the CIM failure impacts more than just the horn (as its a connection inside that has the issue, hence why metal clips were fitted.....)

And Dave...........an earth on a car, really 

Don't be so NEGATIVE 

I did say.....

Check the basics first ...

PLUS...
Terry can't check anything because the car is not with him, it's going to a garage i think, and garages are not always honest 
warning him of the possible CIM fail ,so he knows it's an expensive job IF the garage have to replace/reprogram it .will at least prompt him to take a jar of vaseline