This 2012 Chevrolet Express van came in with the complaint that the horn was stuck on and the the battery goes dead even though the horn has been disabled/disconnected. The customer could not accurately explain how the horn had been disconnected. I figured that the fuse or the relay must have been removed. The cover on the underhood fuse box is about a half pain in the rear to remove and install. To the left of the fuse box in the next picture is a narrow cover. There are two locking tabs. One at the top and one at the bottom.
The main cover has several more latches that have to be released. The two cover have to be separated in order to fully remove the cover.
I like to fully remove the covers because it gives a little more room and it allows me to actually read the fuse box legend.
The horn fuse is number 16 and it is a yellow 20 amp mini fuse.
It had been removed in order to stop the horn from blowing but it did not disengage the horn relay. In case you wanted to know the horn relay is built into the fuse box assembly and is not replaceable. I am pointing to the fuse in the next couple of pictures….
…..so you can see where it is actually located. I had already disabled the horn relay from staying engaged and reinstalled the fuse so you would have a visual on it.
In diagnosing this problem I consulted a wiring diagram and TSB’s to see what all might be involved. After a review of the listed information I found that the horn switch and wiring, the BCM and an odd problem with phone apps installed interfering with the OnStar system. Experience was telling me it was most likely in the horn switch and/or it’s wiring. The horn switch and wiring is under the driver’s airbag so I needed to remove that starting with disconnecting the battery and then removing the lower dash trim panel. It is held in place by two bolts with 10mm heads along the lower edge.
There are also multiple retainers around the outer edge of the panel.
The instrument cluster trim panel needs to be held in place with one hand while you using the other to pull the lower panel loose.
There are four 10mm nuts securing the inner knee bolster.
There are also a couple of 7mm screws holding plastic bracket to it’s lower edge.
Once the last of the fasteners is removed the panel has to be wiggled around and twisted in order to remove it from the dash.
The backside of the knee bolster panel as it lays on the floor.
The yellow connector with the orange positive assurance clip is for the driver’s airbag. Pulling the orange clip from one end then allows the locking tab to be depressed. The battery had already been disconnected for about twenty minutes.
After the airbag connector was disconnected I loosened the 7 mm screw in the center of the in line connector block. Then pulled to two halves apart. Reconnecting the battery and installing the horn fuse no longer resulted in the horn blowing so I knew I was on the right track.
Next I needed to remove the airbag in the steering column. I used an 1/8″ Allen wrench to depress the locking lever through the side access holes. One each side.
I wanted to show you just what you are trying to depress with the Allen wrench. Notice the round hole just slightly left of center in the next picture. There is vertical rod inside the opening.
With the tool you need to push the vertical rod towards the center of the steering wheel. Then lift up on the airbag to release the clips.
In the next picture just above my thumb you will see the black plastic pin that locks into the hole mentioned above. Also note that I am pointing to the locking tab that secures the wiring harness to the airbag. It has to be pulled out first then the main connector can be pulled from the airbag. Be sure to follow the manufacturer’s instructions for handling the airbag properly. Remember it is an explosive device and can really inflict pain or even cause death if improperly handled.
Suspecting that the horn switch contacts were faulty I disconnected the harness that attaches to the top side of the airbag clock spring assembly. Connected the in line harness connector that was disconnected earlier and the horn would still blow. This proved that the problem was between the in line connector and the internal workings of the clock spring. So much for a simple faulty horn switch. Since I was already here I decided to go ahead and remove the steering wheel so that access to the remaining parts would be easier.
Pulling the steering column requires a set of special “j” style bolts that work in combination with my standard steering wheel puller kit.
The “J'” bolt has to be inserted into the slot on either side of the steering wheel.
Then rotated so that the arrow points inward towards the shaft. Repeat with the other bolt and remove the wheel with the puller.
The steering column covers can be removed without pulling the steering wheel but it is easier with it removed. Also at this point I was pretty sure the clockspring assembly would need to be replaced.
The tilt lever handle has to be pried loose. If your grip is strong enough you can just grab a hold of it and pull it loose.
I disconnected the 10 cavity harness connector from the underside of the clock spring assembly and the horn no longer blew proving that there was an internal short to ground inside the assembly.
From this point the snap ring holding down the clock spring module was about all that had to be removed to finish changing the part.
There was a wire tie that had to be removed and replaced as shown below. There also is a reusable harness clamp that has to be opened to remove the harness from the column.
Before removing the steering wheel and/or the clock spring assembly make sure the front wheels are pointed straight forward. The new part comes pre timed and locked to this position.
Once the new part is installed the orange tab needs to be broken off as shown below.
Another successful repair. As always remember to “Stop Guessing and Start Testing”.