no start on 96 tacoma, question on pulse signals

[lowrango]

ok, i'm trying to get a friends 96 tacoma 2wd 4cyl running again. the truck has been at 2 shops doing suspension and body work and came out missing fuses and having several blown fuses. at this point eveything in truck works except she doesn't get spark. the coils get the 12v constant, but i don't get a pulse signal when cranking. i also checked the cam shaft position sensor and crank shaft position sensor for some type of pulse signal at the ecu connector when cranking, nothing. how much voltage should these be? i only have a 12 volt test light with me, so maybe that's why i'm not getting anything. i also checked all the power and grounds to the ecu, coils, crankshaft position sensor and cam shaft position sensors, all test good. i have a feeling the ecu was probably burnt out(truck had alot of welding done to it) but b4 giving the owner bad news, i wanted to verify i'm testing it correctly. thanx in advance.

[hayabusa3303]

the way to test and cam sensor is disconnected use a digital mutlimeter and and see if current passes tho it if it does its good and doesnt its bad. Never Never use a test light on around the engine always volt meters you can burn up the ecm if tested wrong. If you can borrow or get a hold of a scantool for OBDII computers and plug it in and see if the computer is alive or dead and what codes are in the ecm.

If alot of welding has been done with the battery connected then the ecm i would say is dead.

If alot of fuses have blow check the wiring to make sure they didnt hit any of the wiring harness in the truck.

[golfer]

Originally Posted by hayabusa3303

the way to test and cam sensor is disconnected use a digital mutlimeter and and see if current passes tho it if it does its good and doesnt its bad. Never Never use a test light on around the engine always volt meters you can burn up the ecm if tested wrong. If you can borrow or get a hold of a scantool for OBDII computers and plug it in and see if the computer is alive or dead and what codes are in the ecm.

If alot of welding has been done with the battery connected then the ecm i would say is dead.

If alot of fuses have blow check the wiring to make sure they didnt hit any of the wiring harness in the truck.

I totally agree !

It sounds like the bone heads didn't disconnect the battery when they were welding. This helps to isolate the electronics from the current of the welder.

The safe practice for welding on a modern vehicle is first disconnect the battery and have the ground clamp from the welder as close to the area that's being welded. For example , if the ground clamp is at the front and welding is at the rear then the current from the welder flows the entire vehicle , NOT GOOD.

The test light draws too much current and will damage the electronics in a vehicle , besides you can't tell if there is 8 volts or 12 volts with a test light, always use a multimeter.

[josefm93]

since the truck has some body work. make sure the ground that goes from battery to the left fender is attached.

[Toyo Tech]

Maybe someone put connectors in the wrong place?
Or a short in a ground wire if several fuses keep blowing?

And golfer is right don't use a test light it's not that great to use if you want to test circuits
get your hands on a multimeter