Engine just turns off but will restart immediately (2 Viewers)

[AZMoonshadow]

I'm having a weird occurrence with my 2000 LC. Recently, while driving (or sitting at a stoplight) the engine just turns off. (As if the ignition was switched off) If I'm moving at the time, the engine will restart on its own after some high blood pressure moments.... If I am stopped at the time, I can then put the transmission into Park or Neutral and the engine restarts immediately. There is no surging, stumbling, wheezing, or any other noises or malfunctions nor are there any codes thrown. I've researched here on Mud to no avail. This just started to happen in the last 30 days. There has been a lot done to the vehicle since I got it a year ago, but nothing to the intake, batteries, ignition, etc... in the last 4 months. Has anyone ever heard of this? The engine/transmission temps are fine during all of this, but the air conditioner is on... ???????

 

[YezusLX]

Just a guess here, but have you tried using a different key and seeing if you get the same results?

 

[Slickspawn]

Happen over bumps or when cold or warm or is it totally intermittent? Do you have a lot of extra stuff hanging from your key ring?

You could try the harness wiggle test. Start it up and then gently wiggle every harness you can find safely. Under hood. Inside kick panel junction blocks. ECU connections. Wiggle your key. Wiggle the ignition connection under the dash by your feet.

 

[AZMoonshadow]

Hmmm.... These are really good questions. I live in Tucson, AZ so it's warm most days. It appears to be very intermittent. I will jump on these suggestions (including using a different key) tomorrow morning. Thanks!!

 

[medtro]

I'm having a weird occurrence with my 2000 LC. Recently, while driving (or sitting at a stoplight) the engine just turns off. (As if the ignition was switched off) If I'm moving at the time, the engine will restart on its own after some high blood pressure moments....

Trying to understand what I read here. Are you saying the engine will restart itself without you turning the key and while your transmission shifter is at "D"?

 

[awesomeissquid]

I would be curious if when you are moving and the engine dies are you currently applying throttle or is the engine just coasting.

 

[OffRte66]

I had a problem very similar with a vehicle of a different make/model.

That problem turned out to be a lightweight swag lanyard that I dedicated to hanging the single key around my neck with.

An absolute nightmare to diagnose, and the very last thing that I considered.

 

[AZMoonshadow]

I would be curious if when you are moving and the engine dies are you currently applying throttle or is the engine just coasting.

Applying throttle while moving. If stopped, I have to shift transmission into P or N and then turn the key.

 

[AZMoonshadow]

Trying to understand what I read here. Are you saying the engine will restart itself without you turning the key and while your transmission shifter is at "D"?

Yes, with the ignition on, it has "come back to life" while moving and feathering the gas.

 

[SLiggwood]

Check battery cables and grounds.

 

[KliersLC]

I'd also check the crank position sensor wiring, particularly if the timing belt was replaced in the last year or so. The wiring is usually not returned to the exact factory routing and the serpentine belt rubs on it, causing issues similar to yours.

 

[BnvS]

I had a problem very similar with a vehicle of a different make/model.

That problem turned out to be a lightweight swag lanyard that I dedicated to hanging the single key around my neck with.

An absolute nightmare to diagnose, and the very last thing that I considered.

So basically you are saying sometimes weight can cause this issue? i.e. makes the key to miss align and not send immobilizer correct signal or something similar..

 

[BnvS]

Check battery cables and grounds.

While you are checking that...also check as the other member said all other cables.. But also specifically the alternator cables...and ECU cables...(which on the LC is located behind the glove box IIRC. Good luck.

 

[AZMoonshadow]

So, I've checked all the cables, and everything appears to be tight. With the engine running, I "wiggled" every cable I could find under the hood, under the dash, etc. and nothing. I then drove into town with only the key in the ignition and no other keys on the ring. No issues... we'll see... Thanks for all of the hints and suggestions. The belt was changed at Toyota almost two years ago. We'll keep checking things. Just plain weird!!!

 

[Slickspawn]

The key ring weight thing is real. It sank General Motors a while back and again changed the landscape for safety recalls amongst automakers.

The junction blocks under the kick panels are no joke on these trucks too, especially if the windshield channels are rusted or a hack-ass job was done with a prior windshield replacement.

 

[RootMeanSqr]

I had very similar issues. With everything off, I could turn the key to ON, and after some period of time, the starter would engage and it would start itself. Other times,while running, it would die. I eventually decided that it was the starter relay, causing the starter to engage. This seemed to cause both issues. I replace the starter relay and it immediately solved the issue, no problems since. Its pretty much the only way the engine can be started if you're not moving. (other than something physically moving the ignition key.)

The starter relay is relatively inexpensive and pretty simple to replace, once you find it (driver kick panel??), I would suggest just replacing it and going from there.

 

[McNalty]

Sounds like fuel pump, intially they exhibit this behavior. My two cents

 

[BnvS]

Sounds like fuel pump, intially they exhibit this behavior. My two cents

Well at least replacing the fuel pump in the LC LX is relatively easy to replace. Many threads on how to do it and also I am sure YouTube guides on it.

 

[RootMeanSqr]

Sounds like fuel pump, intially they exhibit this behavior. My two cents

I don't follow how a bad fuel pump could cause an engine to start. If the vehicle is not moving, literally the only way to start it is by engaging the starter. Fuel pump has nothing to do with this. OP also noted that the car has to be in Park or Neutral, look at the wire diagrams, truck must be in P or N for starter to engage. You'll also see that the only things in the circuit to engage the starter are the ignition key and the starter relay. So I still vote for the starter relay.

 

[McNalty]

I misread his explanation, I thought the car would turn off and then start right back up. I understood this happened while driving and no additional input from the driver. Sorry for my misunderstanding. Covid brain is my only excuse.