Some Bizarre Behavior from My 2021 Tundra

Hello All,

I have a 2021 SR5 with the TRD Sport Package. I bought the truck new, and it now has 58,000 miles on it. It has been rock solid, and I'm very happy with it.

About a week ago, I fueled up then went on a 200-mile trip. A day or so later, the "Check Engine" light came on. I checked and determined that I had failed to screw the gas cap back on when I filled up about 200 miles prior. The cap was still sitting in its little temporary slot on the back side of the fuel filler door. So the fuel tank was basically sitting wide-open. Of course, I screwed the cap on. Right away, I noticed the left turn signal was blinking quickly. I checked, and the left rear turn signal bulb would not illuminate. The left front turn signal bulb would illuminate, though. And the cruise control would not come on at all--no little green icon on the dashboard, nothing.

I figured the "Check Engine" light was caused by the open fuel filler, but the code did not clear for about a half-dozen trips, including the 200-mile drive home yesterday. I was planning to take it into the dealership and have it looked at. But when I started it this morning, the "Check Engine" light was off, and the cruise control was working again. However, the left rear turn signal is still out. To my question...

Were these three occurrences ("Check Engine" light, left rear turn signal, cruise control) all related, or were they a coincidence? I'm wondering because I intend to change the rear turn signal bulbs this evening and hope this will be the end of it.

Thank you!

 

I could see Toyota engineers restricting the use of cruise if a CEL was on. No proof of this but can see why it may be a good idea. The turn signal is most likely purely coincidental.

 

The hyperflash is because the turn signal is dead - the measured resistance in the circuit isn’t what it expects so it hyperflashes. I doubt it’s related to the other two - just coincidence (unless you’ve got a wiring short somewhere).

the cruise control could be due to the check engine light (CEL). Not sure on the Toyota, but other vehicles (like Subaru) will disable cruise if there’s any active trouble code.

regarding the CEL - you would need to do a code read to confirm any/all active codes. Most common is that gas cap, but if you’re sure it’s closed (two clicks) and hasn’t cleared after a half-dozen trips then there may be other codes.

 

I just had a mental picture of the fuel nozzle remaining in the fill port while you drove off and the breakaway doing it's job with the hose beating your turn signal filament to death.

 

Cruise will not work with CEL on.

Rapid blinking is because you have a burnt out bulb. No coincidences with the CEL

replace bulb and all will be good