Tesla’s Screen Saga Shows Why Automotive Grade Matters

One of the most dramatic illustrations of both the benefits and downsides of Tesla's approach to automaking comes from its decision to use 17-inch touch screens in its Model S and X. No automaker had ever used a screen even close to as large as the model Tesla used, and it instantly became a symbol of its entire approach to building cars like mobile devices. In the brutally competitive premium car market, the gigantic display became a rare example of a feature that totally differentiates Tesla's product from even its far newer competitors.

But rarely is the question asked: why haven't other automakers kept up with Tesla's competition and installed a similarly massive screen in their cars? After all, if Tesla can buy such a screen from a supplier why can't Mercedes or Lexus? In order to answer this question, we must turn first to Ashlee Vance's biography of Elon Musk in which he brags about the process of sourcing the Model S display.

The screen Tesla ended up going with was the Innolux G170J1-LE1, which was designed for industrial rather than automotive applications. As such it was tested to a higher standard than many laptop screens, and its reliability test criteria (found on page 22 of this data sheet for rev C3 of the part [PDF]) might seem impressive to anyone outside of automotive supply chain professionals. Some of these standards include:

Keep in mind that this is a later revision introduced in 2016, whereas earlier versions were slightly less stringent. Turning to the AEC-Q100 standard for automotive grade thermal testing [PDF], we find that the standards for the parts that go into your car are much higher. Here is a quick rundown of a few of the thermal standards:

As we can see, the Innolux screen is tested to roughly the lowest "Grade 4" standard, although even there its high temperature storage testing (as well as high temperatures in thermal cycling testing) falls slightly short. Electronic parts qualified for "passenger compartment hotspots" like a central display are typically tested to Grade 2, which the Innolux would almost certainly fail to pass. Dashboards and center stacks see some of the highest interior temperatures in  a car, with +80C easily achieved through solar radiation and ambient temperature alone, and the nearby HVAC unit, the in-car processor for Autopilot and the display processor itselfadding considerable thermal load.

Tesla's decision to use a large display that wasn't tested to higher automotive grade standards had fairly predictable results. First the Model S and X screens were

plagued by

a bizarre problem that was clearly caused by thermal issues: bubbles would form on the sides of the displays and eventually leak a gooey adhesive material into the car's interior. Tesla appeared to mostly fix this problem with its "cabin overheat protection" feature (which it sold as being to protect dogs and children, despite the fact that it held the temperature at +40C which is about the temperature where a child's organs will start shutting down) as well as revisions to the Innolux panel. Intriguingly, a blog post at Mentor Graphics suggests that Innolux was struggling with thermal management on a screen for an unspecified "high end automobile," ultimately concluding that "defining the boundary conditions for Innolux’s system is the responsibility of their customer, not Innolux."

This was followed by another problem with Model S and X screens, which seems to have been even more widespread: the infamous "yellow banding" problem. This was similar to problems found on a number of touchscreen devices, from iPhones to Microsoft Surfaces, and it too seems to be the result of high thermal loads. Though "only" a cosmetic issue, many owners report having had Tesla replace their screens (in some cases multiple times) to address the problem. Ultimately, around the end of 2018 Tesla stopped replacing screens and told owners it was developing its own solution in-house, saying the new screen units would be available in the Summer of 2019. 

As early as April 19th, 2019, Tesla owners began to report that new screens were available and that replacement appointments could be scheduled. At least two pro-Tesla Youtubers did receive the new replacement screen, but another owner posted an invoice that suggested the new unit was simply remanufactured. Then, this Friday reports started coming in stating that Tesla had suddenly changed its mind and that yellowing screens would not be replaced for free (a recent rumor suggests that Tesla is discontinuing all "goodwill repairs"). The first owner to report this has a five-month-old car with the yellowing screen, and has already endured a series of hair-raising service issues, and at least two others had an appointment to replace his screen canceled unceremoniously. 

The latest word directly from Tesla comes from yet another forum poster, who relays the following message from a Tesla service rep:

Another message, reportedly from Tesla service, reads

Reports are still coming in, and though we aren't yet sure how Tesla will ultimately deal with this saga that has been playing out for years we can at least divine an important lesson from it. This story illustrates why the auto industry moves slowly, tests relentlessly and emphasizes automotive grade reliability and performance over the latest tech and the largest screens. Using a smaller, more expensive automotive grade screen might have cost as much or more per unit and might not have impressed as many consumers, but it might have at least saved Tesla from years of free replacements, bogged-down service centers, and frustrated customers. Especially at mass-market scale, it's always worthwhile to take your lumps upfront than to try to skate by with unqualified hardware and fix units one by one as they fail. 

In fairness, other automakers have had issues with touchscreens as well. Just last year, Ford settled a class action lawsuit over a host of problems with its MyFordTouch systems and had previously extended warranty coverage for its SYNC systems. Cadillac had to recently revamp its CUE touchscreen system after numerous issues including "the dreaded spiderweb cracks." But it's one thing for a few products in a lineup to have problems, especially if they can be pushed onto the supplier, and quite another for the only car in your lineup (until the Model 3 started shipping in real volume last year) to have such persistent issues with one of their main features. Meanwhile, the real question that this all raises is still to be answered: how well did Tesla learn this lesson with its Model 3?