Anti-theft red light on solid when key off

Somehwere I read to check the AC voltage across the battery to see if something is wrong with the alternator. I didn’t really know what it meant but I tried it on this battery when connected to the alternaotr and I was seeing 26 volts AC. For shits and giggles I tried it on my truck and I got 0 volts. Then my wife’s Highlander and got 0 volts. So it made me wonder…but I don’t know what I was wondering about really. The post did say should read 0 volts AC if you try it.

 

@Williston youre right. But my issue was that it’s supposed to blink when the car is off and go away when the car is on. But it stays on solid no matter what you do. I can live with it as long as as it isn’t draining battery.

 

Is this what I unplug?

 

That's an AC ripple test, that's checking the diodes in the alternator.
The regulator is a separate component.

 

Yes.

 

Ok. Separate component but part of the alternator. Meaning not another part next to it.

 

Correct.

 

Thank you for the response. I finally caught up so I deleted my original post response as redundant. Good luck! Welcome to TacomaWorld. You're in good hands on this one with @Dm93 driving the boat

 

I can see that. I’d rather pay him to fix my car than the guys I just did. Because they charged me $2k and told me it was within spec. When clearly it’s not. And they had it for a week with 10 hours of labor.

 

Good news is I get some good listening time to my old friends Alice In Chains while it do all this!

 

Any way I can tell which module is staying awake? Without ripping apart dash…

 

….and confirmed the 2.3 mV went away when alternator unplugged. Also drop parasitic to roughly 300 ma.

 

@Williston have any links to good YouTube’s on resetting?

 

I mean the Transponder Key ECU is the most likely suspect being the security light is staying on.

I found it on mine, it's directly above the steering column.
It may be possible to reach in there and unplug it with something but plugging it back in would be a chore and removing it looks like a job.

If you look up from the bottom right above the steering shaft theres a small hole you can see it through.

 

I tried to get a picture of it but it's pretty hard.

 

Quick Google search with "resetting tacoma anti-theft module" gets a good selection of choices. ** Be careful and tread lightly with this Gizmo. I understand they (Toyota) makes it very hard to obtain a replacment from them, it's expensive and taking apart the dash to get at it in it's hidden/hiding place on the firewall is a total nightmare: you have to take apart everything and risk having a completely dead truck when you put it all back together and turn the key. (speaking about 2nd gens' and later here)

I have heard a rumor that a salvage swap module from another bone-yard truck won't be able to talk to the truck it's going into: something along the lines that the salvage/used module knows the truck you're swapping it into isn't it's real mother...(or maybe vice versa).

 

Pretty sure you can use a used one providing it's the same part number, there's a 30 min relearn using a jumper to "pair" the Transponder Key ECU and ECM.
The part where you need a scan tool that can do immobilizer is pairing the keys to the Transponder Key ECU.

If you could get at least one master key from the donor truck that's already paired to the ECU it would make the process much easier.

 

I’m taking back in on Monday to that shop and telling them what I found. I’m going to let them deal with it. I don’t mind doing the alternator myself but the transponder ECU is another beast. Switching gears since I started looking at the 4WD lights just blinking away…and I can switch to your other thread if you’d like..I didn’t even get pass the T1,T2&T3 voltages in all modes. Because I had 0.43 volts on T1 in all three modes (2H, 4H, and 4Lo). And T2 and T3 had 0 volts in all three modes. I’m assuming it’s the actuator motor on the 4WD actuator.

 

Hopefully they know what they are doing but it doesn't seem like it based on what you said.

I'd rather keep everything in this thread, the 4wd thread is already cluttered as it is.

Unplug the Transfer Case Actuator and see if TL1, TL2, and TL3 go to 12v. If they do then yea we are dealing with an actuator issue, if they don't then it's either wiring or the 4wd ECU.

 

Excellent choice..and yes, @Dm93 has you in great hands here.

IF it ends up the alternator, buy a remanufactured from Toyota. Buy once cry once.