Mass air flow sensor

I have an 06 4runner sport 4.7 and I dumped thousands into changing the O2 sensors exhaust manifolds and entire exhaust system but have been unable to get it from throwing a code for O2 sensors bank 1 sensor 2 and bank 2 sensor 1. Well I couldn't get it inspected and a year and a half had passed, thank goodness for the fake pandemic because NY suspended vehicle inspection but I couldn't figure it out nor could my mechanic. Sovi moved to South Carolina and now I'm having an issue with the MAF SENSOR At first I got a new one, it worked great then it didn't so I got another but it still would only run off of O2 sensors, come to find out, there was no 12v going to the maf sensor and I couldn't follow it back so I just ran a direct line but I can't remember if I hooked the direct line up to the wire going into the sensor or to the sensor and the original line that is supposed to carry the load. Anyway I'll comeback to that. Well it worked great for awhile then I noticed there is something wrong, I started to lose power again and it stalled and couldn't get it started so I took off the direct 12v to the maf and it started again but only by automatic car starter, the key would only start to immediately stop so I went to check the relays and when pushing the DEF relay back in, it popped and started to smoke, so I took it back out, then nothing worked so I had to take the entire fuse box out and rewire half of the wires one at a time and being that I didn't have 90 different wire schemes I used the same color wire for each and labeled each wire on each end with a P-Touch incase more than one came apart. Well that took 2 days. But that only allowed me to start it but only with the auto starter. Come to find out there was no ignition relay in there, I don't know if there ever was or if someone stole it? Well I found out the HTR had one but it was a 5 prong relay and it had only a 4 prong and when I replaced it, you'll never guess what it fixed? The damn O2 sensor problem I spent thousands on trying to fix. WTFF!? BUT NOW BACK TO THE MAF, EVERYTIME I HOOK THE DIRECT 12V TO THE MAF, IT STALLS BUT WITH ALL THE RELAYS WORKING EXCEPT FOR THE DEF (IM NOT SURE EXACTLY ALL WHAT THAT IS FOR?) AND IT SEEMS TO ACCELERATE FARTHER THAN IT DID BEFORE AND IM NOT SURE IF THATS BECAUSE THE O2 SENSORS ARE WORKING AGAIN OR IF THERES 12V GOING BACK THROUGH THE ORIGINAL MAF LINE AND THE MAF JUST ISN'T WORKING AGAIN OR IF ITS THE DEF RELAY OR ALL 3? ATLEAST NOW I CAN USE MY KEY TO START IT. WAS WONDERING IF ANYONE KNOWS HOW TO EXACTLY READ THESE WIRE DIAGRAMS I GOT, BECAUSE I HAVE THEM ALL. OR IF ANYONE HAS ANY IDEA WHAT IS ALL CONNECTED TO THE DEF TO BE CAUSING MY REAR DEFROSTER NOT TO WORK EVEN THOUGH I CHANGED THE RELAY

 

Sounds like you won that battle. Keep up the good work!

 

Don't give up. You're half way there.

 

If you have the knowhow to use a multimeter and/or tone reader do so and trace each wire coming out of the MAF sensor to the ECU, DEF relay to the ECU/defroster itself, and your O2 sensors in your exhaust system back to ECU. If not, take it to a shop you trust and ask them to.