2006 problem vexing me!

My great, usually very reliable 06 tundra is finally giving me a problem I can't figure out! Started it up a few mornings ago, and got the rapid blinkers that usually indicate a burned out bulb. All bulbs are OK, and it turns out that only the rear blinkers were working, nothing up front. Then noticed a brake warning light, and the check engine light also came on and I noticed the alternator gauge was reading a bit low. My error code reader only noted a bad speed sensor. Tested the battery with engine off, it read 13.4 volts. With engine on it dropped to 11 volts, apparently indicating a bad alternator. Replaced that, but still have all the same issues. The truck is running on the battery and I can watch the alternator gauge drop as I run the engine.

To summarize:
--rapidly blinking turn indicator, but all bulbs are good
--only rear blinkers work, not front, same for emergency blinkers
--check engine and brake warning lights on, but error code reader only says bad speed sensor
--alternator not charging battery, replaced with new alternator but all problems persist
--all problems appear to be related as this all started at the same time

The nearest Toyota dealer is 90 miles away and I am really hoping I don't have to arrange for a $400 towing trip. Any suggestions of what I might test or look for next would be appreciated!

D.

 

Can you please clarify: Are you running any exterior LED turn/head/fog lights? Have you had your battery tested?

Assuming none, first thing I'd be checking is the battery connections are tight and free of corrosion, checking all positive cables for corrosion inside the sheath, confirming the status of all engine bay grounds.

I say this because of the sudden drop when running. Makes me suspect positive side of things, or subsequently the ground side of things, isn't getting the bandwidth it needs to supply power.

 

X2 on checking the cables. Mine had corroded on the inside of the wire sheathing.

I didn’t have your issues, but I had a weak starting situation and fluctuating voltage.

I don’t have any frame rust, so not sure why my wires corroded.

Second question would be do you have mice or rat issues?

 

Coastal salty air and copper ??

 

Thanks for the suggestions so far. Battery is only a couple years old and is not the problem. Not running anything extra, truck is still basically stock with 100K+ miles. No salty sea air here in southern Utah to worry about, and no signs of rat or mouse problems. My local automotive shop has been doing the standard oil and related minor services on this vehicle for years (never have had a major issue, love this vehicle) and knows this truck, but they are not Toyota specialists. They suspect a "bad instrument cluster" after exhausting the other possibilities they could come up with, but I am very hesitant to buy such an expensive part just on a frustrated guess (not to mention that the part is on weeks-long backorder).

I did search for this type of problem on this and other Toyota web sites, but couldn't find anything that seemed similar to my particular set of suddenly occurring issues.

I did experience the corrosion-in-the-cables thing years ago, it threw me because it was not visible and the battery/contact connections were all clean, but a shop owner friend figured it out pretty quickly. Unfortunately, he has since retired and closed his shop. Shifty's suggestion for rodent problems is a good one with the sudden onset of all these issues, I'll take another closer look but in town here with all the cats around we don't generally see that problem. Out in the hills my 1943 jeep and old M37 had to be continually purged of rodents, so at least I know what to look for.
D.

 

Are you making this claim because you've had it tested with a professional test unit that checks voltage, CA, and CCA? I only press on this b/c I've owned dozens of cars and have seen multiple batteries die in a year or less of manufacture due to defect, driving habit, and unresolved parasitic draw. Age means jack shit.

All of the problems you list could absolutely be caused by a bad battery, or bad cables. Either of those can light up the gauge cluster like a Christmas tree. Any local big-chain auto parts store will test your battery for free, it only takes a minute. You'll need a DMM and some basic knowledge to test the cables.

The other thing that could cause it, if you've replaced any bulbs lately, is a bad bulb housing. See here. Did you or anyone else change any bulbs recently?

If so, maybe pop that bulb back out again and see if the problem resolves.

Corrosion happens in all environments. Your battery naturally off-gasses corrosives at the terminal post, this is what causes terminals to corrode. That can easily get into the copper stranding of your cables and corrode them from the inside out, completely invisible inside the sheath. A competent shop can test for this, if they're smart and willing.

In my years here, both before and after signing up for an account "bad instrument cluster" has never really been a thing for these trucks, not that I ever recall. As you'll see in this reply, I recall a LOT of shit that's gone down here over time.

I've heard of single gauges going out. I've heard of the fuse block in the dash getting corroded from windshield leaks causing weird crap to happen. I've heard of voltage gauges jumping, gas gauges failing, but never once heard of a bad cluster.

This is a red flag to me, their suggesting it could be that, and that they'd let you buy a replacement. You can get used ones on eBay, or at a local salvage yard though, if you really wanted to test this theory. While in there, check the wiring behind the cluster for signs of rodent damage.

That's OK, based on what I'm reading, I wouldn't want this place doing anything except basic maintenance.

If you're unwilling to investigate the basics, like testing your positive cables, checking all of your fuses in the dash and under-hood, having a friend jiggle the main power wires around (fat one and the skinnier one that jumps to the under-hood fuse/relay box) while you sit in the cab and watch the cluster, and taking the truck to the LAPS for battery test, now would be the time you want to go to a certified Toyota mechanic to look at your issue.

Any dealership will hook your truck up and perform just diagnostics on your vehicle. Just because you bring it to them doesn't mean you're on the hook for them to do the repair. Of course, they'll want to do the work also, but you can kindly refuse with no consequence, but I'd make it clear when you call up the service department you need diags only. But you may not need to go to a dealership. You may have a certified Toyota mechanic closer. Like, in Atlanta, we have ToyoTechs, LexTechs, just two of the big ones that focus on Toyota only and have all the tools the dealer has.

If you suspect rodents, these trucks use soy-based cable sleeves and hoses all over the place. This is a long and arduous journey to pursue, literal game of detective + 'cat & mouse'

They like to get up under the manifold and nest up like this.

They like to chew gas lines like this.

They like to shred air filters, causing crap to get sucked into the intake like this.

They like to systematically remove filters and replace them like this. (this one always makes me lmao)

Some guys have popped off the blower motor behind/under the glove box and found evidence of them there, or in the vent tubing, or in the evap coil housing.

If you can pop your radio out, checking the wiring bundles that pass behind/around it could be worthwhile too.

Your ECU is behind the glove box, I'd check to make sure its wiring is intact there also, and if you can pop your ECU out, open its clamshell, check it for water damage.

And on water damage note, if you can look at the back of your in-dash fusebox to check for signs of water damage like this, that could be worthwhile also.

 

Agree with @shifty` .
High percentage play with these problem threads is
#1. Battery. Don’t assume, test.
#2. Cables. Hard to “see” as you mentioned. Clean the terminals and wiggle em a bit to see if anything changes.
#3. Bulb sockets. Corrosion or poor fit due to age.
4. Any of the other random crap.

 

OK, I threw in the towel on this one and got it to the Toyota dealership (we are 85 miles from town and no authorized Toyota shops any closer). It turns out to be dreaded rodent problem, they got up behind the dash where I could not see and chewed through a bunch of wires in "the worst possible place" according to the Toyota folks. It's not going to be a cheap repair, but at least we'll have our good old Tundra back in a few days. Now I'm worried about our Prius and our inherited Rav4! Soy based wiring, huh? Jeez.

Thanks for all the discussion and help offered by you all, it's been appreciated.

D.

 

Only because it was mentioned by a member due to stolen CATS, they filed comprehensive claim with their insurance.
Perhaps rat issues could fall in this category.

 

Glad you’ve pinpointed the problem, sorry it’s a big one. Hope all goes well with the repairs and they get you back on the road soon!