UPDATE/SOLUTION AT BOTTOM

As the title says, I just had my transmission replaced with a remanufactured unit from Yota1 in Riverbank, Ca. These guys are the consummate professionals who really know our trucks and are passionate about making them better. I want to be clear this post reflects zero negative views or opinions toward them. This post only serves to hopefully expedite the solution to my problem as I unfortunately live 7hrs away from their shop. As always, the problem didnt rear its ugly head until I was comfortably back home 400+ miles away.

So here's what's going on:

Picked the truck up friday, felt great. Shifted perfectly, everything felt tight (still does) and had no issues stopping/starting on my trip home the following day, (which I did several times for fuel/food/etc.)

Sunday morning I went to grab breakfast, no problems. About an hour later I was headed back out of my house, hop in the truck and when I go to start it the radio cuts off as it usually does when you crank but there was no response under the hood. Voltage at the battery was good, but no click, skip, or anything from the starter. Truck was still "warm" but not near operating temp. I, for whatever reason, thought to kick the shifter down to "L" and back to "P" and try again. Cranked right up. Weird.


So driving to get lunch (it was a very food-centric sunday) everything was fine. We stop for food, come out to the truck and same thing, zero response under the hood when turning the key. No lights, no warnings, no nothing. Just the radio cutting off when the key is full-turn. Tried toggling the shifter through its courses a few times and cranking again... Nothing.


Let the truck sit for 30-40min, came back and bam, first crank started up no problem. I then drove the 20min back home, ~50mph, no problems. Park at the house and shut the truck off, let it sit for about a minute, then tried to crank again. Same issue as before.


I'm leaning toward the neutral safety swtich? The tech said he wasnt sure if the positioning of the switch would need to be adjusted. There is one oblong hole that mounts the switch to the trans, which to me says there is some degree of adjustability? Could it be that the switch, for arguments sake, is positioned 5 degrees to the rear when it needs to be 5 degrees to the front? (This is speculation on my part, I've searched and not been able to find anything about someone positioning the sensor, only replacing or cleaning it)


This is a new sensor, by the way****


Any input greatly appreciated. I'm working with the guys at Yota1 currently to troubleshoot but thought I might better my chances getting this in front of more eyes.


Much appreciated.

UPDATE 1/30/2024

so far:
-replaced the starter with an OEM reman from Toyota
-replaced the starter relay
-cleaned battery terminals and neg-to-fender ground
-all wires from starter to battery appear in good shape (no worn areas, kinks, tears, etc)
-double checked and cleaned starter connections (new starter)
-adjusted shift linkage
-checked connections on neutral safety switch (brand new Toyota part)
-battery was tested a few months ago, in spec. Will have it retested and replaced if needed this week.
I don’t have a multimeter so haven’t been able to check consistency of power so bar any further recommendations this is sort of where my diagnostic abilities seem to be reaching their limit


2/12/2024 SOLUTION

So it was the neutral safety!!! I’d come to my wits end, wasn’t able to test continuity at home so gave in and brought it to the stealership. They ran through everything I’d done and all the new parts and determined the neutral safety switch wasn’t engaging.

From Toyota “Verified starter relay is not clicking, checked power at relay and had abnormal voltage reading at pin 1. Traced back to neutral/park safety switch and found a poor connection. Reinstalled neutral/park safety switched and verified starter relay now has power. Vehicle now starts after getting to normal operating temp”

Now it starts like a charm every time. Not sure if it was an external attachment or internal component (the tech left for the day when I picked it up) but it’s resolved. I disconnected, cleaned, and reconnected the plug 2x over the past month and a half so to no avail so I assume it wasn’t seated fully and would be out of spec when the engine/trans got to temp. Glad this is sorted and not some electrical gremlin.

Very good thought.. I would check all the connections at the starter.. Being your stating that it didn't engage when hot. Is really learning me to be your stater contacts are warn out. I don't see how many miles on this starter listed. I had one 3rd gen that the connector in the back of they ignition went bad. This fooled me because it acted just like a starter problem. Hence, I replaced a starter for nothing as it was just a worn contact at around 220 to 230K miles. Alternators brushes wear out between 180 to 230K on average so if the starter is OEM with some mileage that maybe the issue. If the starter is aftermarket who knows how long they will last.

I hope this helps as I don't think it was anything to do with the transmission change.. I think you just developed a starter issue or a problem in that starting circuit is all. :-)

This was my first thought. Seeing as I’d just had the transmission replaced and figured the (likely) tired old starter was having trouble given the increased resistance of a new transmission. Everything’s tighter now. The thing that gets me with that diagnosis is that when cold it fires up no problem, no hesitation. Figured the resistance would be less when warm and it would struggle on cold starts if that were the case. Never had an issue like this so I’m just kind of giving my best guess. Yota1 should be getting back to me this morning and I’ll bounce around these ideas with them and report back anything not mentioned

First of all, smart choice getting your rebuilt transmission from Yota1 Performance. I highly approve!

Secondly, there is adjustability with the park neutral safety switch. If your ECU isn't registering you're in Park, it won't let you start the vehicle. If your transmission shifter light on the dash is registering your in "P", then the adjustment should be good. But, you can play around with it a little and see if it changes anything. Have someone in the driver seat with the ignition key on. Loosen the adjuster bolt and then start swiveling the switch one way or the other while your buddy watches the dash light. When the "P" light goes off, you're out of adjustment. Swing it back until the "P" stays green and isn't intermittent.

It certainly could be the starter contacts. You missed an opportunity to renew them while it was out. Did Yota1 do the install for you?

You can use my video to remove, rebuild and reinstall your starter.

Thanks, Tim!

I'd actually reached out to you on instagram when I was hitting dead end after dead end trying to find a new A340F and you highly recommended Yota1. Cant thank you enough. I appreciate the suggestion, these guys have been the best. They really went above and beyond without hesitation

I talked with them yesterday and other than the neutral safety I'm going to adjust the shift linkage as well. All of the dash lights correspond with which gear is selected on the shifter so we're thinking its just out of adjustment by a fraction one way or another and gets exacerbated by thermal expansion. Thats at least the working theory for now. If adjusting the linkage doesnt yield any changes I'll try adjusting the neutral safety a few degrees either direction

That said, a new thing happened that made us think linkage might be part of the issue. I had driven and gotten the truck to operating temp. Pulled in to my parking spot, put my foot on the brake, pulled the e-brake and shut off the truck. Tried to start it after a few seconds and got the same result as before, no crank. I thought to let the e-brake off a little, let the car settle back some, and crank it again. Fired right up. However when I shut it off and tried cranking again a few seconds later it had no response.

Havent had the time to get under there and mess around, too busy at work trying to wrap things up before the holiday. Hopefully will have time thursday or friday to dig in to it. As for now, it starts up perfectly in the morning, gets me to work, and is fine by the time I drive home.

I also suspect the starter as it has to be removed in order to remove the transmission. It may have been handled roughly and loosened a connection or perhaps it was the last straw that did it in. It's a real pain to do though so give yourself lots of time before starting this job.

Park neutral safety switch could be it but I don't remember even touching it when I swapped out my transmission. I did have to mess with the linkage going from the shifter to the transmission as after the first few drives the shifter would slip into neutral if I bumped it. It also slipped from "D" to "2" on its own on one occasion. I had lined up the linkage as before but it wasn't the same with the new transmission. This is an auto we are talking about correct? See if the next time you drive it and shift into park and turn the engine off, if you can move the shifter forwards more and hear it 'click' into place. If yes the linkage needs to be adjusted to the safety switch is engaged. Or manually push the shifter towards P while cranking and see if that does it.

To get the shifter linkage to its happy neutral spot, loosen the nut that attaches the shifter linkage arm to the transmission linkage arm with the shifter in Park. Where the linkage settles after you loosen the nut is neutral. Retighten the nut and see where that gets you.

Auto, correct.

I thought it might not be registering being in park and tried a few times to really mash it in to park. No change. All dash lights correspond with the shifter position also. Havent tried pushing toward P and starting, will do so this evening after driving home, thanks. Also, behaves the same if I try start it from Neutral, as well.


The weirdest part of the whole equation is the heat factor. It ONLY happens after warming up the truck. Hopefully a little adjustment of either the linkage or neutral safety will do the trick

Another thing I discussed with Yota1 was the potential the connection to the neutral safety switch are needing to be cleaned/re-seated. That's the only potential cause I could see where heat would be a factor. The connector isnt quite seated and when cold isnt an issue but once warmed up its behaving differently. Who knows. Auto transmissions are like sorcery to me

Hmm, when mine did that a few times I heard and felt and audible 'click' as it popped into place. Your issue seems to be a bit different. I would still look it as a potential issue but also the starter. The switch would be an easier fix than the starter though.

Update, kind of.

Replaced the starter with an OEM denso, cleaned the connections to the starter, replaced the starter relay and STILL have the same issue.

Simply put, if I drive and get the truck to temp, stop (think running in to the gas station for a drink) and try start the truck again, nothing. Sometimes I’ll get a single click, usually nothing. Then, once it seems she’s cooled off enough it fires up no problem. Heat, it seems, is the constant here. If I drive around the block and don’t get to temp, it’ll fire right up after I shut it off.


What else should I check now?

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So this morning I cleaned my battery terminals and connections, ground from the neg terminal to fender, connection at the starter. Drove to the hardware store, far enough for it to get up to temp, shut it off, came back out and *click*…nothing. As said before, brand new reman OEM starter, starter relay switch, battery is about a year old and read well when tested like a month ago.

Any points in the right direction greatly appreciated.

Did you consider the Fuel Pressure Regulator?

Increasing the fuel pressure in the rails is what it's there for. When the engine, and thus the fuel rails, gets good and hot, there can be a great deal of bubbles forming in the liquid, causing lack of functionality in the injectors. The pressure regulator will increase the pressure the rails are under, decreasing the amount of bubbles that can form in the liquid. Once it cools down, the fuel rails will no longer need the higher pressure, and the fuel pressure regulator will decrease the pressure to the normal function pressure.

All this is controlled by the temperature sensor, I believe that also feeds the ECU, which then activates a VSV, applying vacuum to the pressure regulator, increasing the pressure. The pressure regulator is operated by a diaphragm, which is known to tear, thus no longer functioning. Less common a problem, but still a possibility, is the vacuum line feeding the FPR leaking, and/or the VSV ceasing to function.

Just a few thoughts I got. I get so few any more...
Pat☺

Would excessive pressure in the rails cause the starter to behave that way? I’d get that if it had a hard time cranking but what I’m experiencing it doesn’t even get the chance to crank. Not a *thunk* like the starter tried to cycle the engine, just a flat *CLICK* from the starter. I’m going to have the battery tested again this week. It’s still under warranty might just see if I can get it replaced. I’ll check the FPR and VSV this evening. I know my charcoal canister is going bad so that could be an off chance culprit. Thanks for the input 🤙🏼

Fuel pressure or vapor circuits could cause the engine to crank over but not fire up, but not a 'click' situation. There's a problem with your starter circuit - relay or wiring. That's all I got for you, something might have been damaged during the transmission repair, especially if they tried to yank the transmission out and forgot to unbolt the starter.

2/12/2024 SOLUTION

So it was the neutral safety!!! I’d come to my wits end, wasn’t able to test continuity at home so gave in and brought it to the stealership. They ran through everything I’d done and all the new parts and determined the neutral safety switch wasn’t engaging.

From Toyota “Verified starter relay is not clicking, checked power at relay and had abnormal voltage reading at pin 1. Traced back to neutral/park safety switch and found a poor connection. Reinstalled neutral/park safety switched and verified starter relay now has power. Vehicle now starts after getting to normal operating temp”

Now it starts like a charm every time. Not sure if it was an external attachment or internal component (the tech left for the day when I picked it up) but it’s resolved. I disconnected, cleaned, and reconnected the plug 2x over the past month and a half so to no avail so I assume it wasn’t seated fully and would be out of spec when the engine/trans got to temp. Glad this is sorted and not some electrical gremlin.