Hey All,

The horn is not working on my 08 ML320 CDI.
Here is the troubleshooting ive done so far:
1. Checked the fuse and its ok.
2. Checked the relay and its ok.
3. Took the horns and manually wired 12v wire from the battery terminal and they wok fine.
4. Thinking the last thing was the clock spring. Went ahead and replaced the clock spring. Horns still now working.

Please help me fix the damn horns!?!?

Thanks

 

What fuse and relay in what fuse box did you check?

 

Sorry I missed your reply.

I checked the fuse circled in red and the relay next to it in the engine bay - passenger side fuse box.

 

Dinismb, I do not think the problem is with a fuse or relay, it must be with the removal & installation of the Clock Spring.

Who replaced the Clock Spring?

 

Maj Dundee I did it myself. I paid very close attention to how I removed the old one and installed the new one.

it wasnt working even with the old spring.

I followed every step on this procedure

 

Do you have a scanner to check for codes?

 

Heres what I get from the icarsoft scanner. However Ive replaced the relay and also swapped one from another location. Nothing is happening.

 

Locate the horns behind the grille and test the BROWN wires for GROUND. If not, check W2 ground location for GROUND.

Then while assistant blows the horn, check Blue/White wires for 12v.

Have you recently removed the steering wheel for replacement of any component?

 

Maj. Dundee

I will check the brown wires as well as the w2.

Which Blue/White wires are you referring?


I did remove the steering wheel to replace the clock spring. But as I stated above I did this thinking it was the clock spring that was bad that caused the horns to not work.

Thank you for your help sir.

 

The Blue/White wires are where the horns are.

Your problem is probably with the Clock Spring replacement.

 

I had a similar problem. Checked and changed clock spring to no avail. Even changed entire steering wheel. Eventually fixed back my own steering wheel and clock spring. Turns out it was the front SAM located in the battery well under front passenger seat. Had water in the battery well in the past and it seems it affected that particular circuitry. All other functions on the steering wheel and clock spring were working fine.
From the experience, i advise anyone with a similar challenge to check the SAM if you can find a functional one to test with before purchasing.

 

Have you tried using the panic button on the key fob? If the horn sounds disable it with the unlock button and look for a problem in the Front SAM, water in the left wheel well (driver's side if left hand drive), etc.

 

Since you've already ruled out the fuse and relay and even swapped out the clock spring, you're covering all the bases. Maybe it's worth going over the wiring again with a fine-tooth comb. Sometimes, there's a tiny break or frayed wire causing all the fuss.

 

After, I tried all the possible troubleshooting, I suspect its the from SAM as many have suggested. I was going to remove the sam and clean it and check for any corrosion, I have been putting it out for long time because I have not had any time as this is a whole days project. I will check for frayed wires as well. As of right now it remains a mystery still.

 

It sounds like you've been through quite the troubleshooting process with your horn. Taking a closer look at the SAM and checking for any corrosion or frayed wires definitely seems like a good next step. Hopefully, you'll crack the mystery soon!

 

By the way, if you're ever considering upgrading your horn setup, you might want to check out the Dewalt train horn for some added punch.