Cranky Toyota

My wife's 2013 Toyota Tundra has a cranking condition. It cranks great but when you let off the crank position to the run position it just keeps cranking until you turn the key to the off position
so yes you could say it's a crank no start. Here's where it gets weird, I had the solenoid relay pulled out of the fuse box the I was checking the power coming to energize the relay and I found 12 volt power coming to energize the relay After checking it a few times I noticed the 4LO light on and the Check Engine light on. When I put the relay back in the truck started normally!!!!
The 4 LO light was still on as was the Ck Engine light but the truck started and ran every time I tried it. I scanned the code and it was for the Crank sensor (P0355) but even after clearing the code the Truck still started. Until the next day and it was back to cranking in crank and run position but not starting.
So what I'm thinking is the PCM (that controls all of this) is not see enough voltage generated from the crank sensor so that's why it keeps cranking???
I'm going to try a crank sensor tomorrow

 

I wouldn't replace anything, with the exception of the relay. At least I'm starting to suspect the relay. I'm having a similar issue, along with a fail to start. I had a couple theories between heat soak and wiring, but I haven't found any of these. My 02 Celica does similar things, and I have to constantly jump the relay to start it. Either way I've swapped my crank sensor back to OEM, since I swapped it out when my starter died a few years ago. It gave me the same code, and now when it doesn't start it will give me the 0355 along with all of its friends. All 4 position camshaft sensors. I've swapped bank 1 A to B and am having the same issue...

 

Truck is supposed to go through a crank cycle when you turn the key. It’s called bump start in some vehicles. Not starting is another issue. Is your truck Flex Fuel?

 

Can be Fuel Pump Control Module. $50-300 on ebay.