How to stop rats from eating our Toyota Tundra?

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Update by J.G. Pasterjak to the Toyota Tundra project car
Apr 10, 2024 | Toyota, Wiring, Tundra

While we love our 2010 Toyota Tundra for doing truck stuff, doing truck stuff is not an everyday occurrence. Our Tundra will occasionally sit for as much as a couple weeks in between trips, which presents its own set of maintenance hazards.

We recently learned this the hard way when the check engine light glowed. We’ve had CELs before on this ultra-reliable truck, but usually for minor offenses like a loose gas cap.

This time, though, the CEL came with drivability issues, namely an unwillingness to shift past fourth gear and decidedly middling performance while it got there.

The codes indicated that the knock sensors weren’t hooked up, which would put the truck’s 5.7-liter V8 into limp mode. Some cursory research revealed that these trucks, as well as other 5.7-liter-powered Toyota vehicles like the Sequoia, frequently have knock sensor issues–but not due to sensor failure but, rather, due to their delicious harnesses.

Apparently whatever coating Toyota used as an anti-corrosion insulator on the knock sensor harness–many corners of the internet believe it to be seed oil-based–serves as an irresistible treat for rodents and other small mammals.

The knock sensors and their associated harness are located in the valley of the V, under the plastic intake manifold, along with some soft foam insulating pads. So, basically, in the gap between the intake and the valley, Toyota built a DIY rat condo with a roof, bedding and snacks.

Once Spiker Motorsports removed our truck’s intake manifold, we saw that, for once, the internet was correct. Our truck’s knock sensor harness looked like a corn cob after a cookout, and was completely gnawed off in more than a few spots.

The good news here is that a replacement harness doesn’t cost much. This is such a common problem that your local Toyota dealer should stock the factory item, while aftermarket suppliers like Dorman even offer a replacement that should be as close as your local auto parts store. The aftermarket option retails for less than $50 locally and close to half that online.

The bad news is that accessing the harness requires the removal of the intake manifold, which is a bit of an involved process, but certainly not out of the reach of the hobby mechanic with a few hours to spare.

We’ve never found a reliable solution to keeping rodents out of engine compartments. We’ve heard everything from Irish Spring soap to ultrasonic screamers that produce a tone that can’t be heard by humans, but the rats seem smarter than anything we can come up with and we’ll occasionally find evidence of rodent intrusion after long periods of inactivity.

The most reliable method we’ve found for keeping them out is regular use of the truck. If you have any suggestions for reliable rodent repellant, we’d love to hear them in the comments.

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Comments
Colin Wood
Colin Wood Associate Editor
4/10/24 12:55 p.m.

I heard great things about the Tundra on RatYelp.

HotNotch
HotNotch Reader
4/10/24 12:55 p.m.

Honda Rat Tape, and Mothballs

Kpgarage
Kpgarage New Reader
4/10/24 1:23 p.m.

There is company called Grandpa Gus that sells repellent bags that work well in our RV. I know that part of the problem is that some electrical wiring is made from soy bean based material which attracts the rodents. Until I found the Grandpa Gus products, I was even considering a cat. That is a tall order for someone with four jack russells. They love to hunt vermin but the collateral damage is probably higher. 

J.A. Ackley
J.A. Ackley Senior Editor
4/10/24 1:46 p.m.

I've used some repellent bags, too, for the garage my Caddy is in. It seems to keep the mice out of the car, but not out of the garage. I take it the repellent bags work best in enclosed spaces.

Every few months I come back to the area where the car is and refill a big bowl of mice bait/poison in the garage. Every time it's gone. I haven't seen any rodent damage but they're obviously still there if they're eating it. 

OnTheChip
OnTheChip New Reader
4/10/24 2:20 p.m.

Squirrels chewed a harness in my son's CX-5.

Coniglio Rampante
Coniglio Rampante Reader
4/10/24 2:26 p.m.

The YouTube algorithm knows me well, and one channel it sends my way is called Just Rolled In, which is comprised of videos submitted by auto technicians and the absolute garbage that people bring in and want fixed...most often it's completely botched DIY things.

Anyway, one recent clip had a customer who was complaining about mice.  The tech opened the door to find a large snake, with a mouse in its mouth, retreating back into the dash from the pedal area.  The customer failed to mention his DIY solution of putting his pet snake in the car to get the mice.

At least Nature solved one problem.

So yeah, you live in Florida...there are all kinds of snakes there.  Find one and let Nature run its course.wink

Noddaz
Noddaz GRM+ Memberand PowerDork
4/10/24 3:36 p.m.

Mouse tape.

Part number 4019-2317

It is about $40 per roll.

The mouse tape is supposed to be infused with some sort of hot pepper....  Stuff.

I wonder if you could just squirt some sriracha sauce on there.  That stuff goes on anything.

z31maniac
z31maniac MegaDork
4/10/24 3:41 p.m.
J.A. Ackley said:

I've used some repellent bags, too, for the garage my Caddy is in. It seems to keep the mice out of the car, but not out of the garage. I take it the repellent bags work best in enclosed spaces.

Every few months I come back to the area where the car is and refill a big bowl of mice bait/poison in the garage. Every time it's gone. I haven't seen any rodent damage but they're obviously still there if they're eating it. 

We had a specialist company come out and completely seal the exterior of the house, no more mouse problem. They don't use bait/poison as they said if they eat it then die behind a wall you're going to have a stinky problem for a long time. 

Msterbee
Msterbee Reader
4/10/24 3:58 p.m.

My Kia Forte GT's engine harness got munched on by some critter a few summer's ago.  Stupidly, Kia decided that not having an engine sub-harness was a perfectly good idea so the entire electrical harness had to be replaced. With all the attendent delays and headaches you might imagine that entails. Fortunately insurance covered it... angry

Msterbee
Msterbee Reader
4/10/24 3:59 p.m.
Coniglio Rampante said:

The YouTube algorithm knows me well, and one channel it sends my way is called Just Rolled In, which is comprised of videos submitted by auto technicians and the absolute garbage that people bring in and want fixed...most often it's completely botched DIY things.

Anyway, one recent clip had a customer who was complaining about mice.  The tech opened the door to find a large snake, with a mouse in its mouth, retreating back into the dash from the pedal area.  The customer failed to mention his DIY solution of putting his pet snake in the car to get the mice.

At least Nature solved one problem.

So yeah, you live in Florida...there are all kinds of snakes there.  Find one and let Nature run its course.wink

I have never watched one of those videos.  Just seeing the icon and title is enough. laugh

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