Mysterious Electrical Problem

About a month or so ago I took my 2012 Tacoma in for its 60K service. Besides replacing the plugs and oil change I had the cooling system flushed and front brakes redone. Drove off and it ran smoother than after the 30K plug change so I was happy. Later in the day I cranked the truck, put it in gear and attempted to drive off. As I did this it lurched and “choked out” so to speak. Problem was it refused to crank. The starter turned over but that is all. I then had it hauled back to the dealership, they tried to crank it but to no avail. Told me it was dead, must have been hit by lightning. I told them that wasn’t the case but two of services I had paid for, replacing the spark plugs and servicing the brakes, had a function in cranking would they please do a little investigating.

Two days later they said it was ready. They did not fine anything definitive, said they had to do a “cold restart on the engine computer “. It has run fine up until yesterday when it did the same thing and now waits to be towed again to a Toyota dealer but this time a different one.

My questions are has anyone had the same experience, if so what was the cause? What is the engine computer and how does one do a cold restart? Any other tricks I can try to crank it? What can I tell the service people to help them diagnose my problem? THANK YOU FOR YOUR HELP!

 

How so?

 

Because you have to press the brakes to crank the engine, something in the feedback loop might have been compromised. I know nothing about this feature but it could just a sensor on the pedal not in the braking system itself. Something I noticed yesterday was the brake pedal was stiff when trying to recrank my truck, rather like it did not relax back to its normal position.

 

It won't 'relax' until a running engine provides vacuum to the booster.

So you have a pushbutton start, right?

 

Nope, it is a key start.

 

You do not have to press the brake to crank or start the engine.
If you do, you have another problem.

You only need to press the clutch in. If it is an automatic, you need to be in Park or neutral.

 

The stiff brake pedal is normal. If you peas the brakes more than 1 or 2 times with the engine off, it will get stiff.

If you open the hood and leave the window open, you’ll hear the booster purging the air.
This is normal. Once the truck cranks, the booster will return to normal operation.

 

When you say crank. Do you mean the starter will not spin?
Or does the starter spin but not the engine?
Or does the engine spin, but not start.

Let’s clear this up. I feel like we can help you figure this out.

 

The starter spins, not sure about the engine. Unfortunately the truck is about 40 miles from here so I can not check. Did not think about this until just a minute ago but if I took off the battery terminals would that completely shut down the engine computer?

 

Yes. After 30 seconds. The ECM would be off.
But this wouldn’t cause your issue. Nor would it fix it.

 

Then you do not have to press the brake to start. It's not a bad idea to do so safety wise, but not required as it is with a push button start

So.

I'd suggest your brake work has nothing to do with the problem

 

considering you have a transponder key:
https://www.carandtruckremotes.com/products/2012-toyota-tacoma-transponder-key-blank

i'm suspicious of the anti-theft system. typically, a lack of a valid key signal will disable the fuel injectors, resulting in a constant crank situation. but it generally only checks for the valid code at startup, not when running.


the first thing is to make sure that the area around the ignition is clear of trinkets like accessory color rings and the like. after that, i would suggest trying a second key if you have it.

 

TnShooter: The service manager says just removing battery cables then reattaching them does not put the ECM into cold start conditions. Do you have any other suggestions as to how do do this. I know doing this will not fix my problem but if it is easy enough to do I can temporarily get back on the road.

Soundman98: Tried my other key, didn’t work either.

 

this is where we move back to the fundamentals. to work, engines need air, spark, and fuel.

air rarely screws up enough to not allow it to start, but either a clogged filter, or a really bad MAF could be a potential issue here to cause a no-start.

spark, the truck is new enough to have individual coil packs for each plug, so even if the wrong plug was installed, or there was an issue with any of them, it's a 6 out of 1 chance of doing something. it should at least run rough, even if some of the parameters or parts were bad. it's not unheard of for coil packs to go out after plug changes, but extremely unlikely that all 6 will go out, and at the same time.

fuel, will cause a no-start issue if the fuel injectors can't get enough pressure if the pump is either clogged or not working--either because it failed, or a wiring issue from rodents. easiest thing to check is to go up to the truck, unlock it, and turn the accessory on without starting. you should hear the fuel pump 'whine' as it primes the system. testing beyond that really involves diagnostic tools to verify it's working, and outputting the correct pressure.