Toyota Firmware 89663-04A81: Engine Control Calibration

89663-04A81 is a Toyota engine control module calibration identified as 8966304A8100 in Toyota service records. The engine control module manages engine operation and monitors faults that can illuminate the malfunction indicator light. Toyota lists this calibration as an updated version in bulletins covering a specific diagnostic issue and a separate Tacoma update.

Malfunction indicator light and P261093

Toyota Service Bulletin T-SB-0013-19 lists 8966304A8100 as an updated calibration for a malfunction indicator light condition associated with diagnostic trouble code P261093. This code concerns the engine control module’s internal engine-off timer performance. In practical terms, the controller uses timing information after the engine is switched off as part of its diagnostic functions.

The bulletin identifies this calibration as an update in that service context. The code and bulletin are useful starting points for diagnosis, but a lit warning light alone does not identify the cause or establish that this calibration applies to a particular vehicle.

Tacoma service context

Toyota also lists the same full calibration ID as updated in T-SB-0119-18, a bulletin covering the 2016–2018 Tacoma. The available record does not specify that bulletin’s service topic, so it does not establish an additional behavior or improvement for this calibration.

The P261093 bulletin covers several Toyota models, including Prius, Prius Prime, Sienna, Camry and Tacoma. That is the bulletin’s overall scope, not a fitment list for every calibration in it. The catalog filename 89663-04A81.bin names no stock or modified variant.