Tesla HW4 vs HW3 side indicator design and specs comparison shows it can't be retrofit

A recent teardown of the Hardware 4.0 self-driving kit of Tesla that its newer vehicle batches come equipped with hinted that HW4 may not be easily retrofitted to its current HW3 crop of electric cars. Unfortunately, a  side-by-side comparison of the side repeater coming with Hardware 4.0 now comes as a tangential proof that a retrofit is either not possible or would be very hard to do.

The HW4 side indicator comes not only with a new camera, but also a new connector, while the FSD computer that commands it all has different dimensions and wiring harness as well. Recent buyers of the Model Y whose vehicle came with the old Hardware 3.0 kit might be a bit miffed to hear that the HW4 side repeater, part number 1820735-00-C, can't simply be plugged in as it has an entirely different connector and harness, too.

Moreover, the HW4 part consumes much less power than the current HW3 side repeater with part number : 1495865-20-D. Despite the way larger FSD camera, the Hardware 4.0 repeater is marked as 16V / 0.9W on the side, whereas the HW3 equivalent has 12V / 2.2W markings. Tesla started installing Li-ion auxiliary batteries in its vehicles instead of the lead-acid ones that used to die much more often on Teslas than on other vehicles.

The aging 12V automotive system that has been around since the 50s and is being strained by all the electric components and computing power in a modern vehicle. In any case, a 16V system is much more efficient for all the computing, accessory, and entertainment needs of a Tesla, as the new side repeater indicates.

Unfortunately, only owners of newer Model S/X/Y can take advantage of the HW4 goods, while prospective Model 3 buyers would probably have to wait for the Highland redesign later this year to get on the Hardware 4.0 bandwagon.

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