Looking for Tundra Electrical System Expertise

Hey everybody

I'll add additional detail below, but for those who don't want to read it, my question is: What could I possibly have done to the electrical system that would simultaneously impact power to the head unit, VSC/traction control, and what I assume was system voltage (indicated by erratic voltage gauge and flickering dome lights) while not impacting the engine (and then suddenly be fine a few moments later)?

Yesterday, while driving on some loose gravel roads, I experienced a simultaneous occurrence of a VSC/Collision avoidance error on the dash and a momentary loss of power to the radio. The VSC/Collision avoidance issue I've previously seen when in sand or mud and there's some sort of interference withe the wheel speed sensors. I've never seen the radio reset before though, and tbh it took me a few moments of driving before I registered that it happened.

The VSC error resolved itself when I toggled the traction control button on and then off again back to auto-LSD mode, and the radio went back to operating normally. Throughout all of this, the continued to drive normally as far as I could tell.

After I stopped the vehicle (running and in park) a few moments later, I noticed that the dome light was flickering and the voltage gauge was acting erractically (at and around 14v, but still more erratic than I've ever seen it just idling). I let it continue to run as at this point I was concerned it would not start again if I turned it off (and I was pretty far out into the woods). It corrected itself a few minutes later and I drove home without issue. I'm comfortable with a latent VSC issue that I can't figure out, but I'm much less comfortable with an issue that could potentially result in the vehicle not having enough juice to run or charge the battery and leaving me stranded out in the woods, so I'm hopeful to figure out what caused my experience.

 

Perhaps a grounding issue? Or something got wet?

 

That makes the most sense to me. I also came a cross a few cases of shorts occurring while off-roading due cracked circuitry and/or a bare ware touching in the back of the head unit which I thought might also be the culprit. The only thing that's throwing me off is the lingering voltage issue after all-other symptoms resolved. That lasted for approximately 10 minutes after everything else.

 

Quick Update for anyone who stumbles across this post

I've visually inspected the wheel sensors and found nothing obviously wrong with them, but I scanned for codes and came up with the following (keep in mind, all warning lights/errors have gone away at this point):

C1201 Brake Boost Sensor Circuit Range/Performance
C1241 Low battery positive voltage or abnormally high battery positive voltage
C1434 Steering Angle Sensor Output
C1465 Front Speed Sensor LH Circuit

My son killed the battery a few days earlier, so I'm unsure of the C1241 code was still there from that incident or not (Regardless, I've checked the battery and it currently has good voltage). Some of the others I've seen with previous wheel speed sensors issues that resolved themself. I'm now wondering I potentially have a damaged connection causing an intermittent short in my Wheel Sensor circuit. I've re-set everything and will drive for a while to see if anything pops back up.

 

I too had the above-typed situation twice when I took my TRD Pro onto the drive-on beach where I attempted to fish.
Trailer brake problem, lane departure, and VSC lights filled the instrument display when the truck jerked up and down and swayed its rear end as I lost traction on the soft sand.
Park Ranger helped with the traction problem as I had to air down my tires but the error messages never went away until I took it to the dealer for warranty repair back in 2020.
No explanation or replacement of the yaw sensor was mentioned by the dealership where I purchased the truck.

Fast forward to June 2023 and again I encountered the above error lights when I took the truck out to the beach for some fishing.
Again, I didn't air down the tires as I replaced the stock Michelin truck tires with Nitto mud and snow tires.
I took it back to the dealership in July as I had some recalls on the truck to be tended to.
They couldn't fix the problem... and ended up breaking the surf rod that I had stashed perpendicular in a rod hold on the bed of the truck when their triage tech drove my truck through a low-height garage door exit.
They didn't even mention it to me until I nearly drove off. Just send us the bill was their way of fessing up.
I won't go back to them.

A few months later in September, I decided to have another dealership look at the problem.
"What did you do again? was their response but let us have a look at it." We will charge you for diagnostics and apply the diagnostic charge to the actual repair.
3 hours later and we found the problem.
It seems your voltages are fluctuating between 11.5 and 12.5 volts which is causing the ECU to give these errors.
You also have lots of aftermarket electrical devices connected too.
Yes, I do but they don't draw voltage except when I connect things to it (front and rear heavy-duty battery to winch connection points), ARB compressor on a relayed switch, Remote starter, and a solar panel charger to the battery.
So I went home and removed all of the voltage and current draining devices.
I still have the problems.
I brought an Autel scanning device, and again, it thinks the ECU needs to be reprogrammed.

So next week, I will bring the truck back to the second dealership and demand they fix it.

I let you know what they found.

 

Have you verified alternator charging voltage and battery voltage?

 

My problem has been resolved but at a cost and lots of wasted time.

The original dealership fixed the same problem back in 2020 under warranty when I took my truck "beach fishing" and didn't air down the tires.

Fast forward two more years and under new and bigger-sized M/S tires (Nitto Road Grappers), I again didn't air down the tire thus having the whole dashboard light up again (Trailer towing fault, ABS, Headlamp adjustment fault, etc)

I brought the truck into the original dealership for recall work and had them try to fix the problem again.

They performed the recall work and couldn't even diagnose the problem. I asked them to look up what they did two years ago and heard crickets when they told me they couldn't.
They also broke my surf rod which was vertically stored in a rod tube located on top of my Decked storage when they drove it under a "low" exit roller exit.
And they didn't inform me of the breakage either until I confronted them about it.

Time to find another dealership to fix the problem.
They ran diagnostics and told me I had fluctuating voltages and needed to add an aux battery as I had fluctuating voltages from 12.5 to 11.5 volts.
They told me they recalibrated the steering angle too.
They cleared the ABS fault and my speedometer worked again.
They did not want to reload my ECU even though my Autel diagnostic tool recommend such with all the faults being tied to this component.

I went home and disconnected all of my electrical accessories but still had the error flaws.
I tried to clear the flaws using the Autel unit to erase such but got the ABS and speedometer faults back again.
I didn't use the truck for a couple of months as this truck is my adventure one which I use it to go fishing and camping with.
I also disconnected the battery during this time.

Last Friday, I brought the truck back in and complained that their diagnostics were not correct as I had removed those accessories that might have caused the voltage fluctuations and the problems still exists.

Here is the reality of what happens when you bring your vehicle into a dealership for their problem-solving.
1. you are going to pay especially if your vehicle is no longer on its warranty.
2. the service representative repeats what their "master mechanics" tell them.
3. diagnostic service will be applied to the problem resolution within a month (I don't recall being informed of this).
4. they will charge you by the hour to troubleshoot the components that their diagnostic tool couldn't pinpoint.
5. each dealership does not share its out-of-warranty resolutions with other dealerships let alone the warranty solutions. The dealerships can see other warranty and recall work (no costs to fix information) only if the other dealership is on some common application and network tool. Toyota headquarters doesn't get involved in escalations unless enough vehicles start to exhibit the same problems and isolation to a component(s).

My steering angle unit was shorted to ground thus causing all the other safety systems and components to also cry wolf.
And my dealership never heard of or seen this problem before.

Conclusion:
1. air down your tires to prevent your truck from fishtailing or pitching up and down should you drive on loose surfaces at speeds greater than 2 miles per hour
2. the Toyota network for service isn't what it seems to be for collaboration and teamwork for their customers.
3. diagnostic tools have limits and many service techs don't do enough to look at the big picture (how the fault happened and what systems are involved) but look at the after-the-fact parameters which lead them to incorrect conclusions as to what the problem is.

I have faith in the truck but lost my faith in my local dealerships.
peace out

 

I forgot to update this thread; I found a fix! For anyone with similar issues, assuming you've established that it's not actually your wheel speed sensors themselves.

I ended up testing voltage a few times and although it was over 12v running and stopped, it seemed a little low from what a healthy battery should produce. On a hunch, I replaced my battery with a new AGM and....zero issues since.

My theory is that as the battery was nearing the end of it's life and failing to produce maximum voltage, the truck was encountering low voltage faults anytime it needed maximum draw aka when traction control was activated. For whatever reason, that produced the error code pattern I was seeing.