The detailed act sensor test procedure is listed in the link from sbftech at the end of this paragraph.Code 54 should be an indication that the sensor is open internally,a sensor wire is open,the harness plug is suspect or the act circuit in the ecu itself is suspect.Did you check the black/white Signal Return wire too or just run a new wire only to the act signal terminal at the sensor & ecu harness plug??I was gonna suggest checking the act signal wire at the 10 pin connector until you mentioned you had ran a entire new wire.If you haven't checked the signal return wire yet,it runs through the black 10 pin connector at pin #1 which is the center pin.Since all of the 2 & 3 wire sensors share the same signal return wire,if there was a problem with the main section of the wire,all of these sensors would be affected,so therefore if theres a problem with the wire for just the act sensor only,it will most likely be between the sensor & the 10 pin connector itself.Im not sure why you mentioned the 5.0 volt VREF circuit?? Its not used for the act & ect sensors,only a signal & signal return wire is used.The tps,bp & evp are the sensors that use the VREF circuit.
You could also try running whats called the "wiggle test mode" to locate a suspect connector/wire.The procedure is listed at the bottom of this post.
The following link may help you diagnose & solve the problem with it. ACT/IAT Codes 24/54/64 Troubleshooting
In regards to the cel being lit continuously. Anytime the cel remains on,after the engine has been started,and its due to the loss of a sensor signal,the ecu will substitute a fixed value for that sensor so that the vehicle can still be driven until repairs can be made.
ANY code that is set due to a issue thats present currently will be listed as a OD
(On Demand) code & these are the first set of codes that get flashed during the KOEO test.Its also worth noting that these codes will be flashed twice.
ANY code that has been set within the last 80 warmup cycles will be listed as a CM (Continuous Memory) code.These codes will also be flashed twice.The importance of knowing which codes are OD vs CM is to make you aware of which codes are present because of an issue thats occurring right now vs an issue that occurred at some time in the past (i.e.- if an intermittent condition had occurred that self corrected or you forgot to reconnect a sensor harness that you then reconnected after a couple of minutes right after the engine was started)
If there arent any CM codes present right now,code 11 will be flashed instead and the same goes for the OD codes.Once the OD codes (if any) or code 11 is flashed,a 6 second delay followed by a code 10 (seperater pulse) will occur then the CM codes (if any) will be flashed.I only brought this up to explain why your results turned out like they did as a prelude to thefollowing sentence you listed in your post. "The amazing thing is code 11 shows up after the second group finishes."
Your results indicate a act sensor fault is currently present,but no CM codes are present & the CM test passed.A recent battery cable disconnect would have also cleared both code types out then once the engine was started,the OD codes would have immediately been set.
Code 15 is present because of the chip,so don't worry about it.