CAMRY EATING ECU'S.. ECU #5

Good day guys,
My name Vlad, technician for local toyota dealer here in TN as master tech, been in the industry going on close to 10 years, im here to ask for help with this 2011 camry that keeps burning ecu's.


Here is back story, customer bought vehicle "recently" for some reason (unclear why) took it to independant shop, the said  vehicle had dtc for ign coils, has duralast all 4 coils now, way it came in. at some point they noticed alt not charging, replaced alt (use oem) few hrs after new alt vehicle died and wont start. they diag as bad ecu, replaced ecu, one crank attempt and burned it up. brought vehicle to us, i get crank, no start. no cel on comb meter. when through and did my checks, good ecu power and gnd, VC putting out .6 vdc, scan tool says ecu offline during can bus check, resistor inside ecu is good. unplugged every vc component, still getting .6 V. Ordered oem ecu, plug it in, VC has 5V, i write in the vin with oem scan tool, attempt to crank, no start and CEL is not illuminated on comb meter no more, check VC getting 2.2 V. rechecked everything, 12v batt tested bad, replaced 12v batt. (at the time i did not know about alt)
install another oem ecu, same thing all good until attempt to crank. This time i de-pin all VC components at ecu, all coils unplugged, all injectors unplugged, ckp, ac pressure sensor, maf/iat, ocv's, ect, everything unplugged besides knock sensor and all VC de-pined at ecu, if i remember i still had o2 plugged in. plugged in another new oem ecu, VC 5v, write in vin, attempt to start
crank no start, after that crank ecu stayed alive, during each crank im measuring at ecu VC lines (on harness side) for back feed, no back feed. after checking all VC lines, ecu still alive for few minutes next thing i notice cel went off on comb meter, and my VC volt went from 5V to .8V 
Field tech came out, spend 7 hrs on it, at some point he thought VC line to evap canister had continuity, we de-pinned and removed that VC line, he had me reconnect all other VC lines, besides canister but VC components still unplugged, o2 plugged in and alt plugged in, attempt to crank (using oem used ecu) before crank VC 5V, after one crank VC when to .8V, no comm and can bus, ect and iat which as you guys know have resistor internal to ecu, iat and ect also read .8V
opened recently fried used ecu, nothing visible on top side logic board. I will keep on more details in case i forgot something but i tried to include everything, we had this thing for couple months.
looked into alternator, there is one wire that goes from alt to ecu, TIS says with ign on should have 12V, i have 12V unplugged with it plugged in i get 7.5V, hooked up pico, i see it s pulsed, TIS never said it was pulsed, had 2015 camry same engine, same result, 12v unplugged, 7.5 V plugged but never hooked pico to known good vehicle. 
Any help will be appreciated. 
-Vlad

 

front o2 measing 2 ohms and back one 10 ohms

This sounds like a strange issue indeed. The 5v reference circuit is generally robust enough to recover from shorts to ground, however I have seen engine computers get killed when 12v is applied to the 5v circuit.

VC is Toyota for 5v reference circuit I assume?

install another oem ecu, same thing all good until attempt to crank. This time i de-pin all VC components at ecu, all coils unplugged, all injectors unplugged, ckp, ac pressure sensor, maf/iat, ocv's, ect, everything unplugged besides knock sensor and all VC de-pined at ecu, if i remember i still had o2 plugged in. plugged in another new oem ecu, VC 5v, write in vin, attempt to startcrank no start, after that crank ecu stayed alive, during each crank im measuring at ecu VC lines (on harness side) for back feed, no back feed. after checking all VC lines, ecu still alive for few minutes next thing i notice cel went off on comb meter, and my VC volt went from 5V to .8V Field tech came out, spend 7 hrs on it, at some point he thought VC line to evap canister had continuity, we de-pinned and removed that VC line, he had me reconnect all other VC lines, besides canister but VC components still unplugged, o2 plugged in and alt plugged in, attempt to crank (using oem used ecu) before crank VC 5V, after one crank VC when to .8V, no comm and can bus, ect and iat which as you guys know have resistor internal to ecu, iat and ect also read .8V

Was this with the same engine computer? Meaning, did the 5v ref return by the time the field tech came out, or was the computer replaced again?

When checking power and ground at the computer after losing the 5v reference, are you loading the circuits? I'm not doubting your methods, just thinking of variables.

Have you tried bench testing one of the failed modules?



 

ONCE ECU IS OUT 5 V REF DOES NOT RETURN.
ANOTHER ENGINE I MEANT I HAD A CAR SIMILAR CAMRY THAT I COMPARED NUMS OF THE ALT WIRE

I CHECKED GND'S WHILE CRANKING, DURING CRANKING I BELIEVE HIGHEST WE SAW WAS 500mV BUT THATS ENGINE GROUND (A LOT OF NOISE)
THOUGHT TO BENCH TEST IT BUT THATS AT LEAST 5 GNDS AND 3 POWERS SUPPLIES NEED TO BE CONNECTED, I JUST DONT HAVE THAT MANY LEADS/TEST TERMINALS

Unplug your coils and look at all output circuits for a short to power and check your engine grounds

I UNPLUGGED ALL THE COILS. IGF SIG WIRE AT ECU READS 1.3V SPEC IGN ON SHOULD BE 5V, PLUGGING IN COILS DID NOT CHANGE 1.3 V READING.
I THINK BECAUSE WE FRIED ECU IT WONT CHANGE. DID PICO IGF WIRE, HAVE NOT CHECKED IGT. IGF LOOKS NOTHING LIKE IT SHOULD SQUARE WAVE, JUST BUNCH OF NOISE DURING CRANKING, COILS GROUND DURING CRANKING ABOUT 700mV

IGT SIG DURING CRANKING, CYL 1, ALL CYL IGT LOOK ABOUT THE SAME. THIS WAVEFORM LOOKS SIMILAR WHAT I GOT ON IGF AS WELL