Crankshaft position Sensor

Hello Taco lovers. Newbie first thread here. I was given a 95 Tacoma from a friend. I've been rebuilding it with a new complete head and valves and so far everything is great except it is throwing a code saying CPS is faulty. It runs but will stall every once in a while and idles high. I checked the resistance on the sensor 2.1 ohms. Tested voltage from sensor and showed some fluctuation when cranking over. I was told that the red wire coming from the ECU should have power and the green wire is the NE- which sends a signal to the ECU. There is no power on the red wire but it runs when sensor wire is plugged in. When I tried to put power to the red wire and plugged it in , truck won't start. I'm not good with electrical and I am at a loss. Could someone please help if you can? Much appreciated.

 

What engine do you have?

 

2.7L 4cylinder

 

The Crankshaft Position Sensor is a VRS type, it generates it's own signal. The PCM does not supply any power or bias voltage to it.
Essentially both wires are signal wires but NE- is typically at ground and NE/NE+ is the signal line.
If the wiring and sensor test ok with a meter you really need an oscilloscope to properly diagnose the sensor signal.

 

That is very detailed. Thank you for this. I will troubleshoot this right after I fix the problem of my buddy that gave me the truck came over today and helped me jump start the truck and he crossed the cables and blew something/. One row of fuses under the hood have no power. fuses are good but no power. I checked the 40A fuse on the same row and the 80A fusable link and they are good. I guess by the time I get done with fixing these issues I might be pretty good at electrical. When it rains, it pours. I appreciate the PDFs and if you have any insight on this new issue I would owe you big.

 

Thanks for posting Sir.

Every print adds to what I have!!

 

That's not good, hopefully it just popped a fuse.
Here's the fuse power flow diagram, see which fuses are missing power and what fuse feeds them.

 

Was it just a few seconds of sparks till you broke the circuit ??

Trace the circuit of the return path to make a complete Circuit.

Did things quit because something opened??

Quite possible one of the ground connections melted and opened .

On his vehicle or yours or both??

 

It was just a quick spark less than a second. I don't exactly don't know what you mean about something opened. I will check the grounds first thing after work. Yes this truck WAS my friends but he gave it to me. On the Crankshaft sensor, When my friend owned it, when he started up the truck, he would have to rev the motor at about 2000 rpms for a few seconds and then SLOWLY let off of the gas until it gets down to 1500 (if you let off of the gas too fast, it would stall) And then after that initial starting procedure it would run fine. Then I replaced it with a new head and valves then when I started it the truck would fire up and then stall only once, then it would fire up but run at 2000 RPMs or a little higher and would never go down to idle after warming up.

 

So I thought it was a bad sensor and replaced it. Still throwing a code P0336. I just read somewhere else that there are 2 kinds of plugs for crankshaft sensors from Toyota. 2 wire sends A/C voltage through the wire, and a 3 wire which has a power wire and a ground wire and sends a digital OV or SV signal. I don't have any power to the plug on my 3 wire. I tried to splice power on the red wire to the plug and it wouldn't even start. I'm at a loss. Any help would be greatly appreciated.

 

It is a 3 wire sensor but the 3rd wire is a shield wire (ground), it's not a Hall Effect sensor that requires a reference voltage.
Does it run fine but set a P0335 or does it run poorly or stall when the code sets?

 

it used to stall when starting. then ran fine after the initial start. But that was a couple of months ago when my friend owned it. Then he gave it to me and I put a complete brand new head on it and it has stalled maybe twice out of 10 times that I have started it. It just idles high even after it warms up. That's the main thing..... It pulls a 0336 not a 0335 code. Not sure if that makes a difference but my reader says crankshaft position sensor. I traced the wires and they go into a single insulated wire with some kind of foil wrapped inside.

 

That changes things, the P0336 is a cam/crank correlation code. You need to verify the engine and distributor timing.

That's a shield to prevent electrical interference.

 

Well well, I just found out that the guy that replaced the head gasket about 5 years ago didn't put the timing back correctly. That explains the check engine light being on since the repair 5 years ago. The truck ran great in the last 5 years so When I just did the head, I marked everything and put everything back the same way, cause I thought the last guy knew what he was doing. But Nooooooooo. Now the check engine light is off but it idles high. I've done about 10 test drives but still idles high at about 1700 to 1800 rpm's. But every time I get to a stop the rpms go up and down and up and down a few times like it's trying to adjust itself but end up going back to a high idle. I appreciate the help you have given me and I know I am making progress , just have to find out this idle thing.