Key or push button start?
Other than the specifically-mentioned wipers, washer, and horn, what else is included in "everything".
Where are the voltmeter probes connected when you measure random fluctuations? Are those fluctuations occurring in synchronization with the relay "clicks"?
What happens if you temporarily remove the 7.5A fuse marked "ECU IG #1" (located in fuse panel just above the driver,s left knee)?

 

The fluctuations were measured from the relay I pulled the relay up a little bit and stuck the probe to it. Yeah it's spraying wiper fluid wipers are going horns honking lights flashing but nothing on the dash and no codes really. haven't tried that fuse yet I'll try it tomorrow I'm on the interstate right now driving back to my house. Thanks for the reply.

 

Sorry I forgot to mention it's key no push start it's a 08 Avalon XLS.

 

The push button start uses relays to bypass the ignition switch. So it is good news your vehicle is key start, because one potential cause has been eliminated.

Signals from all controls located on the steering wheel / column, including horn, wipers, washers, fog lights, headlights, are multiplexed over a digital series bus to a receiver/decoder in the relay/fuse box under the hood. I think the obvious suspects are either the encoder (located in the wiper switch) or the decoder. These are powered either through the "ECU IG #1" or the
"ECU-B" fuse.

 

 

So that's the little circuit board that detaches from the main fuse box? It has 3 black plugs of various sizes, and then 3 white slightly larger plugs, plus the 2 contact points on the box its self. Which controls those functions! I'm not good with electric stuff on cars. Have new box coming tomorrow morning. Thinking it's that side box. Thanks

 

 

I have a 2007 Avalon limited doing the same thing. I cannot find "power distributor" or "Front controller" in toyota parts search. Got a part number? Is it called something else?

 

Thanks man part worked! But now it's throwing 2 codes for the O² sensors. Both. P0 13-51?

 

O2 sensor Heater circuit malfunction detected.
Check for ~12V on both ends of this fuse with the ignition turned on.

 

🤔. I don't think putting that new decoder on it would blow the fuses. All was well prior. I even checked the one under dash by left knee. No fuses where blown. But who knows, I'll check them again. Since start up something could of blown. Thanks

 

I think the A/F relay is in the module you replaced. If there is no power (or low voltage) to EITHER end of the fuse with ignition turned on, there could be an internal connection issue or some corrosion at the fuse holder. One way to check for corrosion is to remove the fuse, give the fuse terminals a few wipes with a dollar bill, and plug it back in. I also doubt the fuse is blown.

The Engine Control computer measures the heater current and reports a code of that current is below some threshold.

 

Ok. I'll check it out tomorrow or Monday. Thanks an have a great weekend!

 

I think it is item #8 in the image below. It would be a good idea to verify the Toyota part number at a dealer parts counter.

 

It's the Junction Block.