Wage war against '93 Mirror Failure's
April, 2015
Contributed by: Lynn Newport
One of the classic problems found on a 1993 Allante is the failure of its (electro-chromatic) self-dimming rearview mirror. Typically, a seal fails and the corrosive gel found inside the mirror starts to leak. As you can see in the photo, this can cause brown spots to appear within the mirror and eventually it can drip out ruining the circuit boards and even the upholstery. There are many who have had failed mirrors and their dashboards/carpet covered with the indelible fluid. A costly repair for such a small item when/if this does occur.
As some back ground, the first auto-dimming mirrors relied on a photo cell to trigger a small electric motor that rotated a glass plate, much like flipping a manual day/night mirror. In the 80’s, Gentex a small optical company located in Zeeland, Michigan, perfected a rearview mirror that used an electrically triggered self-darkening gel sandwiched between two pieces of glass. The darkness of this electro-chromatic gel was activated by a photo sensor which controlled the current. By the late 80’s, these mirrors started to show up in luxury cars.
It turns out there were two Michigan companies Gentex and Donnelly, who made and still make the lion’s share of self-darkening mirrors. Fierce competition broke out between them. Donnelly wanted in, but Gentex held most the patents. This created what was referred to as the Mirror Wars. Unfortunately our 1993 Allanté’s along with many Mercedes, Audis and BMWs fell victim to the war.
In order to gain market share Donnelly decided to design a very complex rearview mirror with lots of sensitivity adjustments, marketed to high end vehicles. Gentex sued claiming patent infringement. Eventually, they settled out of court and Donnelly agreed to change some of its design elements. One of them was the method of sealing the gel between the two panes of glass. The system adopted tended to fail and over time allowed the gel to leak.
The real question is not - does my mirror leak? But - when will it leak?
As mentioned, the leaking gel is very corrosive and will damage virtually anything it touches. To avoid this the original mirror must be replaced! In ’93 two types of Donnelly OEM Allante mirrors were used. Each utilized built in map lights, but one came with a 6 pin connector, the other a 7 pin. Both designs function identically and can be interchanged by changing out the pin connector feed cable where it plugs in behind the upper passenger front window molding. This cable needs to come with the replacement mirror.
There are a variety of choices for swapping out the mirror with a look-alike model:
• Obtain or have the factory mirror converted to a flip-up day/night design.
• Purchase a new old stock unit that has been re-glazed to prevent gel leakage.
• On the web locate a later year GM mirror that can be substituted for the original.
Check the links on our home page for Allante parts suppliers and be cautious of non OEM interchange parts for proper fit and function.
Though other replacement alternatives exist, these alternatives represent the surest and easiest ways to change your electro-chromatic mirror to one that functions properly with little chance of leakage.
I look forward to seeing you all very soon.
Lynn Newport - AACC Member