05 taco 4.0 engine no spark,help!

[l8drop]

i got a 05 4x4 crew cab,v6 4.0 auto,my code scanner is saying all six coils have circuit malfunction,the coils are individually located on each spark plug. i did a lot of welding on this truck(collision repair) and im wondering if i fried something, i took apart the ecu and it doesnt smell burnt or have any signs of arcing. does anyone know of a main relay someplace besides the fuse boxes? or any other help or things to check appreciated! it cranks fine but no spark,it was running before welding and yes the battery was disconnected before welding. thanx

[TAZZX2]

it wouldn't hurt to start with the bassics.... make sure the cam and crank possition sensors are plugged up right.... go threw and make sure all your grounds threwout the eng bay are fine *its surprising what one small ground wire disconected will do...*

Other that that grab a wirring diagram and a multimeter ,,,, trouble shoot it bit by bit...

[l8drop]

ill check the sensors today,I didnt find any loose ground wires.checked the coils and found the ground wires on all of them are grounded properly but cant seem to get 12v at the coils with the key on. Does it have to be cranked over to get voltage?Each coil has four wires,ground,hot,and probably 2 trigger wires from different sensors or ecu. not sure where to go from here, any help appreciated

[RTFM]

From the sticky above, go here
http://www.markass.com/toyotanation/


download

In_depth_Electrical.zip

Open ignition.pdf

The B-R wire should be hot when your ignition is on or start assuming fuse AM2 is good.

The W-B wires should all be grounded.

The wires going into IGT1-6 will only be hot while cranking, I don't know the voltage, comes from the ECU. probably very brief pulses, may need an analog volt meter to see them.

The W-R wires look like a ground going back to the ECU.

The troubleshooting on page 3 doesn't give you much to go on.


Failing this test, then download enginecontrol_engine type (1GR=V6?), and good luck after that. There's a ton of stuff going into and out of the ECU, and I wouldn't know where to start. Most of the stuff is fine control (knock sensors), and only a few should affect starting. Troubleshooting section here is better, hope it helps.