This module is responsible for making a sound when the door is left open. Fox Body Mustangs are very often prone to stop working or go off at random times and the owner is left with 2 options. Find a refurbished version for sale online or they can fix it themselves.
Here are the steps to fix the chime sound on an 89’ - 91’, but directions should be very similar to all Fox Body Mustangs:
First you will want to disassemble the module
The chime module is attached to a bracket in between the A/C head unit and steering column.
Next you will need to get into the circuit board on the chime module and remove the “pole piece”. This is roughly in the middle of the circuit board and has 3 prongs attached to it that are inserted in 3 holes.
Once the circuit board is removed you can see the diaphragm that is held against the housing by the retaining ring.
Release the 4 clips and remove the diaphragm/retaining ring assembly.
If the diaphragm that is secured to the retaining ring has deteriorated glue a fresh set of hot glue with need to be applied.
Also another ring of hot glue will need to be applied to the top of the dried bumper ring of hot glue.
Then place the retaining ring with the diaphragm and hold together until the glue dries.
Finally reverse these steps to put back in the vehicle.