Aisin AW-4 (30-40LE)

Aisin's four-speed automatic for Jeep — in the Cherokee XJ and the Grand Cherokee ZJ and WJ.

It is a Toyota A340E in a Jeep, which is most of what is worth knowing: the same transmission GM bought as the 30-40LE and Toyota fitted to the Supra. So a Cherokee's automatic has a service literature spanning three companies, and none of them mentions the others.

Its reputation is excellent and that changes what a symptom means. These reach very high mileages, so a slip or a harsh change on one is far more often the fluid, the throttle position sensor or the transmission control module's own connector than a worn clutch pack.

The TPS is the one worth naming, because on this transmission it does more than report load: a drifting sensor makes the gearbox change at the wrong road speed or hunt between third and fourth, and it is an engine-bay part regularly replaced as a transmission fault.

Fluid is Dexron, and these predate sealed-for-life entirely — the interval was specified and is simply often skipped.