Electrical issues with 2017 tundra

45,000 miles. Towed a cargo trailer last year and dashboard went crazy scrambling tow brakes issues. Toyota did diagnostic test and of course said nothing wrong. We didn’t tow after that. Had to replace alternator a few months ago. Again only 45000 miles on 2017. Pull out of driveway last week and the same spastic electronics started again. Any thoughts on what the problem could be?

 

Go to a different dealer and get another diagnostic.

Recount your steps on the tow. What did you do when you hooked up the trailer?

 

Usually when multiple items screw up electrically its time to check battery connections and ground connections. Check all the grounds under the hood that are attached to the body for corrosion.

 

Thank you. We towed the trailer a few times with no issues. Then we heard it was because trailer had LED lights and not compatible with truck. We checked all wiring harness and grounds and didn’t see anything wrong. Will call another Toyota place this week. I will try to video truck when it happens again. We don’t drive it much.

 

How old is your battery? Go to an Autozone and check it. Looks like old or faulty battery to me

 

Ditto on what @JohnWhicker said. Battery going out, low volts will cause all sorts of odd issues and alerts, even when it still has enough power to start and drive the truck.

 

Also check for corrosion and loose battery connections. Mine had corrosion I couldn’t see inside the terminal between it and the battery post.

 

We replaced battery and alternator roughly 2 months ago. Problem still exists. ☹️

 

Do a full reset of the ECM / computer

 

Thank you. Will do.

 

That won’t eradicate corrosion on the terminal unless someone spent the time to do so. Also, the cables may be loose on the new battery. What’s the voltage coming off the alternator? If it’s an aftermarket part it might be spitting out the wrong voltage. I have about a 30% failure rate on aftermarket parts.

 

I always get very suspicious when a shop replaces the alternator and battery at the same time. Tundra's alternators are very reliable. I'm not saying it doesn't happen but it's rare.

 

Thank you everyone for your help. I am dropping truck off tonight at a different dealership. I called Toyota to let them know of issue and if the dealership can’t fix it then I’m going to have to take this issue higher up

 

I think the dealer is just incompetent. Second opinion is the way to go for sure.

 

So dealership said water in harness is causing corrosion. That’s the problem. $1800 for parts and $2500 for labor before tax. Anyone wanna buy a truck???

 

Water in what harness? How’d it get there?

 

Flood vehicle?

 

No not a flood vehicle. We are the only owners.. only towed cargo trailer…no boats..truck is in pristine condition I have no idea how water got in and they didn’t offer reason. I will ask them their thoughts when we pick up truck.

 

This just isn't a problem with Tundras. What harness are they referring to and where exactly is the corrosion? The price sounds as if they want to order a complete wiring harness and install. Can your existing harness be repaired? How about a used harness from a salvage yard?

 

Just a thought. You mentioned the problem didn't start untill you pulled a cargo trailer. Sometimes corrosion can develope at the trailer connector at the back of the truck. The corrosion causes a backfeed to the ground wires and causes all sorts of issues. There is a connector that can be disconnected to isolate the 7 way/4 wire trailer connector. I've run into this a few times and disconnecting the trailer connection solves the issue.

 

Had a jeep once that died on a trip. Shop said I needed new alternator and battery. Had no choice, 500 miles away from home so $1600 later I was on my way.

Got to my destination, lights started dimming. Just made it to drop off at another shop. They found a broken wire to alternator. So in fact I didnt need the new battery and alternator I purchased earlier. Quick wire repair and $50 bucks labor and I was on my way. Never had another issue.

I would get another shops opinion. Agree with @Ruggybuggy , crap gets into the trailer harness plugs and wiring so try cleaning those sections up. And I would find out exactly what harnesses they say have water intrusion.

 

Can they be more specific? Water / corrosion in the harness where? A harness is a continuous bundle of wires that travels from point A to point B or even C. Very unlikely the harness is damaged somewhere from point A to point B but possible. Inspect for any physical damage from A to B where possible, could be some metal that broke into the harness or rodents. But most likely your culprit is the end points, A or B like many here said, check connectors, plugs, etc. etc.

Is easy for incompetent mechanics to diagnose something that complex and they rather change the entire part, in your case the entire harness. It maybe something very simple, or if unlucky something very expensive.

I had something similar in my BMW where a stupid mechanic punctured a harness and everything went high-wire in my car. Was the hardest thing to troubleshoot but when I found the damaged harness I managed to splice it, fix it and move on. It took more time finding the cause than the fix.

 

Thank you all for your input. According to dealership, the wiring harness cannot be modified as it is length specific for working capability. They don’t sell just the end piece that is damaged so the entire wiring harness will need to be replaced. We are picking up truck later today. I will also be looking into salvage vehicles as well. Prices of trucks nowadays and interest-rate really suck. But what good is a truck if you can’t tow ☹️

 

"Specific working capacity"? They want to replace the entire harness because that is what is only available to them from Toyota. No disrespect but your dealer is taking advantage of your lack of vehicle knowledge.

You need to disconnect the trailer wiring connector from the harness and see if see issue goes away. If the problem is resolved purchase a new 7pin/4way trailer connector from Toyota.

 

Agreed. Find another shop to help verify the problem before you get ran through the wringer or throw out what may be a perfectly good truck with a simple problem.

Not saying your dealer is shady, but I’d sure get a second opinion on something that big.

What’s the saying?? “Trust, but verify…”

 

Well there’s your problem right there! It’s all over the side of your truck! I’m pretty it’s protesting the Seahawks.

 

This sounds like a BS excuse from the dealer to me. This does not sound right and they are just wanting to rip you off doing trial and error. I have never heard of water in the harness issue. I'd steer away from this dealer. This does not sound right at all.

 

MOST dealers are not just shady, but are borderline criminals.