Truck not starting p1125 Code

So recently I’ve been having issues with my 2000 tundra 4.7 where it won’t start after I shut the truck off. It cranks but no go.

I was able to get it started after unplugging and plugging back in the throttle motor. And it fires and drives with no issue, unless I shut the truck off then it repeats the issue.

I got a code for p1125 throttle control circuit. So I replaced the throttle motor with a new unit and still does the same thing.

Then I’ve read that it could also mean the pedal position sensor, the sensor on the passenger side of the throttle body, so I borrowed one from my ‘01 sequoia and it still has the no start issue.

I’m not sure where to go from here. Any help would be appreciated

 

Please read this thread from today: https://www.tundras.com/threads/throttle-body-actuator.130009/

It may give you some direction on the code you got.

But when was the last time you did your timing belt? Because your symptoms could be a few other things related to crank position sensor, or fuel resistor.

 

I replaced the timing belt aswell as the crank pos sensor at 296k miles truck is currently at 318k

could a bad maf or tps sensor cause the issue?

could an improperly adjusted throttle cable cause the issue aswell?

Because it’s an intermittent issue, it starts perfectly fine some days and some where it doesn’t.

 

Was the crank position sensor OEM or generic? Generally rule of thumb is to only use Denso parts for anything electrical, for exactly this reason: Flaky ass behavior from other brands (Denso is OEM).

This thread covers a lot of what you need to know about these trucks and quirks, troubleshooting, known problems etc. - https://www.tundras.com/threads/so-you-wanna-buy-just-bought-a-1st-gen-tundra-eh.115928/

Gist is this re: crank position sensor. If it's not working, fuel pump won't continue pumping fuel. It's part of the overall fuel circuit in the ECU's viewpoint. A lot of times after timing belt change, folks don't properly tuck away the crank position sensor wiring where it should be, and the harness flops around, gets nicked, rub-through from a belt or pulley (example of how to tuck below driver's side cam cover if not routed properly). It won't always throw a code, and the nick doesn't always cause consistent failures. Taken from that thread, note the bolded part and click the "pic" link:

• These trucks usually don't have a ton of other electrical issues. Hidden corrosion inside the battery/alt cables happens. Sometimes, a couple thousand miles after timing belt changes, people will have startup issues because the crank position sensor wasn't properly tucked away and gets rubbed by a belt (pic). There's also a similar problem with camshaft position sensor under the cam cover, where the belt will rub through (pics). There's the rodent issues mentioned earlier. Occasionally, water leaks can send water down into the ECM behind the glovebox (pics), or into the fusebox inside the cab/dash (pics and more pics). A lot of drain/vampire issues trace back to aftermarket add-ons whether the owner knows they exist or not - alarms as mentioned earlier, brake controllers, poorly installed trailer receptacles, those are some big ones.

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It's easy enough to check, you know where the sensor is, feel back along its harness for any nicks like what you see in that photo.

Honestly, that thread I linked up top will give you a lot of things to check, including checking for rodent stuff, chewing on the wires on top of the fuel tank.

If it only failed to start when hot, I'd suspect the fuel resistor, which is the finned thing mounted on top of the fender on your 2000, IIRC. You can bypass it to confirm. All that relay does is reduce voltage when the fuel pump relay engages it. Basically, you have two wires from your fuel pump relay, going back to the gas tank: One is a direct hot line (full voltage), the other line routes through that finned resistor, which reduces the line voltage before hitting the fuel pump. Best way I can explain. Lower voltage = less output from pump.

If if fails to start randomly, even when cold, there's a laundry list of stuff to check.

 

Thanks for the pointers, I’ll have to recheck and see if I missed anything.

Just for future reference, what would I have to check if It doesn’t start when cold?

 

Depends on what "doesn't start when cold" means. Like, does that mean ....

• You turn the key forward, and nothing happens, you also hear nothing, not even a click?
• You turn the key forward, and nothing happens, but you hear only a click?
• You turn the key forward, and the engine turns over barely, like the battery is dead, but doesn't fire up?
• You turn the key forward, and the engine turns over strong and consistently, but doesn't fire up?

Any of the first 3 could all point to a dead/dying battery, poor grounds or corrosion in ground or power cables. The 1st one alone could point to, say, maybe faulty ignition, neutral position switch, or even corrosion in the in-dash glovebox. The 2nd alone could point to a bad starter, although unusual, it's not unheard of (and is also a part you always want to buy from Denso). I could go on and on here ...

I assume you've done the basics, like have a local parts store test the battery, even if it's not that old, because quality of 3rd party auto store sourced parts these days, frankly, sucks ass.

That 1st thread I linked above ... check the 4th or 5th paragraph. There's a series of links. One goes to a service manual which will help with diagnostics chains if you prefer a little self-study with process flows.

 

To clarify it cranks strong but doesn’t not fire.

To update my situation, I replugged the crank sensor and it doesn’t start at all anymore. Seems like it’s related to the sensor or the wiring.

• I did a quick visual inspection on the wire and didn’t notice any cuts on the sheathing

I did manage to contact the previous owner, and he “repaired” the crank sensor wiring from when it previously had cut. Probably where my issue is

Im still getting that p1125
Throttle Control Motor Circuit Malfunction
but also got a p1126 code
Magnetic Clutch Circuit Malfunction

But no codes for the crank sensor. I don’t know if these codes are related to my issue

 

Hey, were you ever able to find a solution and get her running?

Facing very similar issue - crank no start with the same code

 

This ended up being a cut wiring harness for the crank position sensor. My cut was around the serpentine belt area and was very minor but it caused my issue.

I repaired the area and now my truck works great, no more codes

 

Yup, that's what I was referring to in my reply above, glad you got it solved. It's so common, it's linked in THE MEGATHREAD, highlighted in red italic here:

• These trucks usually don't have a ton of other electrical issues. Hidden corrosion inside the battery/alt cables happens. Sometimes, a couple thousand miles after timing belt changes, people will have startup issues because the crank position sensor wasn't properly tucked away and gets rubbed by a belt (pic). There's also a similar problem with camshaft position sensor under the cam cover, where the belt will rub through (pics). There's the rodent issues mentioned earlier. Occasionally, water leaks can send water down into the ECM behind the glovebox (pics), or into the fusebox inside the cab/dash (pics & pics & pics, it happens a LOT). Many drain/vampire issues trace back to aftermarket add-ons whether the owner knows they exist or not - alarms as mentioned earlier, brake controllers, poorly installed trailer receptacles, those are some big ones.

And...

• Starting problems: If your truck won't start, or stutters, it's VIRTUALLY NEVER the fuel filter, as mentioned above. It's also typically NOT the starter, and also typically NOT the fuel pump. There's a wild array of other potential causes. If you recently had the timing belt done, check your crankshaft position sensor wiring harness - it's common for the loom to be reinstalled wrong, so it flops out and gets cut by the serpentine belt. Don't use aftermarket or "universal" relays. Make a new thread, honestly. We see 'no start' issues often.

Should be the first thing you check, and if you ever do and/or have your timing belt done, you really need to verify the crank position harness was tucked away from harm properly.

EDIT: For anyone finding this thread in the future with the same codes, we are making progress with BlackFlag over here and tracked his issue down to a fuel delivery problem. It may be worth reading if you find this thread in the future: https://www.tundras.com/threads/p1125-and-p1128-on-a-crank-no-start.145745/