Help, my truck won't turn off, among other things

have you had any water/moisture on your passenger side carpet? maybe the ice created a leak in the hvac drains and got the ECU wet.

 

Sky net has gone live! It’s becoming self aware and rebelling

 

I had thrown the trickle charger on the bluetop while it still had a good charge in my garage, but did not disconnect the battery from the truck, so the vehicles draw simply exceeded the charge rate of ~3A for over 12 hours. Now that I've been driving it a while, and have found that the headlights do not turn off, quite often, when i stop the vehicle, i suspect this is what happened to kill that deep cycle - the main headlights I wrongly assumed would turn off after 30 seconds, did not, when I went inside and eventually went to bed.

I have looked throughout the engine bay, there is no apparent damage to any wiring, droppings, pieces of plastic or other signs of animals. Most of the vehicle function has returned at this point, the fuel is registering (a value of some kind) but i believe it is wrong, the temp sensor still does weird speed related changes and the traction control button still actuates the high beams (but it does indicate it is enabling and disabling the VSC as its supposed to).

Turning the lights off now works about half the time. I'm loath to try and isolate how the momentary contact of the traction control button is actuating the high beam relay, but it is obvious (from an electrical circuit perspective) that voltage is bleeding from that run to the high beam which must be adjacent to it somewhere, a similar voltage bleed must be coming from some portion of the gauge cluster or sensor on the engine/transmission and co-mingling with the outside temperature sensor, and there is an either intermittent short happening with the fuel gauge, or similar voltage interference on that line that is inconsistent. The proximity of all of the various systems to one another are literally spread out across the vehicle. Unless all 6 or these systems terminates in very close proximity to one another, (high beam relay, BSM, temperature, traction control, engine termination switch and fuel level) I don't see how it could be much else than the ECU itself (especially given the relatively recent idling issues w/o an engine code). I'm generally pretty well versed in electrical circuits and tracing errant draws (my day job is in the electrical trade, and I'm a computer systems integrator in my spare time) but I swore a little over a decade ago that I wouldn't modify, or really work on, my vehicles' electrical systems anymore (I'm a firm KISS believer), so I'm going to let Toyota FAFO tomorrow.

I appreciate all of your ideas and input. I'm lucky that this has only been slightly more annoying than it is curious and amusing to me. I would wager most people in this country, if put into a scenario where their vehicle just stop performing (and without workarounds would be inoperable) could easily lose their job or be unable to make ends meet because of it. I'll keep you all posted on what comes out of it, even if I have to eat crow in the process.

 

to clarify, Tacoma has Body control unit and Engine Control Unit (ECU). Both are inside the cabin.

 

If a three amp charger can’t keep up you have a pretty big draw when off. I had to trouble shoot one on my mustang. It can be a pain.

 

Well, Toyota believes they have identified the problem. Sadly, I didn't get a new pet out of the deal, or any indirect causality. It is actually very unsatisfying, all in all.

According to the service department i have a broken fuel pump. Or, more specifically a defective one that was the subject of TSB -0008-23. The solution is to replace the entire fuelpump assembly with a revised part as this one is sending off strange error messages that are (apparently) interfering with nearly every other subsystem in the truck.

On one hand, I'm glad that this is a repair they will render free of charge, and am hopeful it is the only problem present - but at the same time, it is a tad bit alarming that one part, completely unrelated to... literally everything that is screwing up except the fuel gage, could even possibly happen. This is apparently why it was part of a separate recall on other vehicles, but was not prevalent enough on this series of tacoma to be included (?).

Replacement parts are estimated to be 1-2 weeks out, and it is highly recommended i leave it there and not drive it (pansies, but ok). Guess i'mma get lotsa exercise riding my fat bike this month.

https://m.carcomplaints.com/Toyota/Highlander/2020/tsbs/tsb-t-sb-0008-22.shtml

i guess this is what i deserve for having components from a unibody vehicle on my taco... cooties.

 

Strange indeed. Do you get a service loaner? Also, I hope this is not a case of throwing parts a problem the technicians don't understand and the issue is still there after the repair.

 

No, no loaner was offered, or available when I asked. I've been trying to find any similar situations with power/and electrical problems stemming from a fuel pump in toyota vehicles, and am not finding anything, so I too worry about the throwing parts at it and not resolving a more sinister problem. I will probably just end up bumming a car from friends in the meantime, which isn't a huge issue in the short term.

 

welcome to the world of "Dirty power and modern electronics"

 

I got the high pressure fuel pump TSB done about 4-5 years ago, and it greatly reduced ticking at idle. no electrical problems tho. i once had a starter that was draining my battery, on my 99' 4runner.

 

Sorry you feel unsatisfied, but hopefully this corrects the problem. The CAN bus protocol has a lot of built-in checks that shouldn't allow the behavior you mention to happen. I can see what they have in that TSB as possible, but the fuel pump messing up outside temp readings or causing the lights not to turn off is a bit suspect. That said, if they put a sniffer on and actually saw errors being sent from the fuel pump, it likely needs to be replaced anyway. Whether it fixes everything, I guess we will see.

Please come back and let us know the outcome.

 

I’m too, hopeful it’s resolved,,,, but skeptical a fuel pump is going to cause all those electrical type gremlins

 

Update:

The dealership finished replacing the high pressure fuel pump and assembly. Spoiler alert: it's still doing weird crap. The service advisor said the next thing they would recommend doing is replacing the low pressure fuel pump, which is apparently also reporting errors, but that item is not one covered by the service bulletin.

I pushed back at the suggestion as it still doesn't make any sense that the fuel pump would be causing all these oddball problems, and replacing an unrelated mechanical part that would require hours of labor, dropping the fuel tank and tossing out a (potentially perfectly good) part, prior to them isolating the common thread all the faulting systems have in common, sounds like the beginning to a very expensive, long and stressful fishing expedition. It still seems to me that the most likely, and honestly only rational, explanation is that something, somewhere, shorted and the fault is only sufficient enough to cause odd readings across non-critical systems (non-throttle/ powertrain related). I'm still betting on one ECU that just so happens to control the exterior and interior temp sensor, ABS, BSM Traction Control, Ignition, high-beam relay and fuel gauge. All of these loop into the dash display at an indication level, but I don't know the physical location of the controlling device to check the wire harnesses/plug contacts.

I want them to rule this out before we continue the fishing expedition into the individual end point errors. Any thoughts?

 

Thanks for the follow up, and sorry to hear it’s still not fixed. I was rooting for you, but seriously doubting their “diagnosis”, it sound to me; they are now carpet bombing with parts. You may have to find another shop,,, you can’t make them do what they don’t want to do, and by guessing on your dime? They’re done with it,,, back to easy profitable work.

 

They didn't mention the other fuel pump was reporting errors before? I'd ask them to at least try swapping in a known good ECU and taking some more readings.

 

Yea, I would have hoped this would have happened from the start, but clearly some people are less analytical than others..

 

Well, Dilbert won the challenge. Of course this advice was not omnipresent at the dealership, where I had already dropped it off by this time, so it took them another 3-1/2 weeks to get the same answer.

It appears that because, in all their wisdom, Toyota designed the entirety of their major wiring systems to be draped in fabric that perfectly wicks moisture up onto them while simultaneously not sealing any of their connection interfaces, in scenarios where cars do not get to dry out daily (are parked outside and exist in a place where winter is a thing) they will invariably succumb to catastrophic corrosion.

The dealership found a half dozen plugs that are corroded on the drivers side and require replacement of the entire vehicle wiring harness (at $2700 part) that requires in excess of $6000 in labor to replace. They recommended I reach out to Toyota's Corporate Assistance wing to see if they might consider helping rectify the situation, so I did that today. I was told, in a nutshell to pound sand. They did not care that the car was rendered inoperable in just 6 years and 70k miles, just that it was outside of the 3year 36k mile warranty, and it was on the owner to pay for their oversight. This goes without saying, this is my 9th Toyota, 4 of which I purchased brand new. My next steps are to try and cleanup the corrosion, since I can't afford or justify spending nearly 9 grand on a truck that its just going to happen again on because it will continue to live outside and get snow tracked into it, which will thaw and refreeze at some level every day in the winter and be damn sure not to buy another one, which is not what I wanted to be the case.

 

I'm sorry to be the winner. I hay have had some experience in that area. I was denied warranty coverage, while under warranty, due to aftermarket wiring.
https://www.tacomaworld.com/threads/cab-water-leak-causing-possessed-tpms.575128/

 

Are you the original owner? This looks like a flood car or you have a leak somewhere (windshield?) getting water on those.