I hooked up my battery cables backwards and blew the fusible link. I have replaced the link but now the ETCS fuse keeps popping removed all the wires from the fusible link hooked battery back up the fuse blows as soon as I hook up the white wire with a blue stripe back to the fusible link . Tried infotech for wiring diagram but it's not available for the is250 if anyone has a clue what that wire runs to I would greatly appreciate it

 

I'll try and look on www.alldatadiy.com at my 350 schematic and report back later. Compared to the other links, is the fuse smaller or larger? It looks to be a 14 gauge wire or maybe a 12gauge. Can you confirm?

You might disconnect it and power it up. See what doesn't work. Also with it disconnected, ohm it to ground and report back.
It may be a dead short or a partial short.
Also with it disconnected and the FB powered, verify it has no feed back by setting meter to volts and probes to ground and wire.

 

Just so we are clear; is it blowing a fuseable link or a replacement fuse? The replaceable fuses and relays are marked inside the cover.

 

It blowing the ETCS fuse on the other fuse box on the drivers side it's a replaceable 10 fuse.

 

How do you know it's that wire causing it?

Ohm out the input to the ETCS and if its shorted, i.e. low or zero ohms than fix that problem.

A 10A fuse likely has a 5 Amp load or less. So if the input is less than 5 ohms it blows the fuse. More realistic is >50 ohms the fuse lives.

 

Went back and disconnected everything from the fuse link hooked the battery back up and went through each wire that is bolted to it and with nothing connected but the three plugs and that wire it blows. All the other wires it's fine fuse is fine as soon as we touched that wire to the fuse link it popped.

 

Does the test method i wrote make sense?
You need to fix the issue on the other side of the ETCS fuse not the white/blue trace wire. Maybe leave the fuse out and start it. Clear errors and then check for BCM errors. The OBD Fusion app with Toyota Lexus PID add on will help.

 

In short, follow the ETCS fuse to the device that is shorted.

The reverse terminals likely shorted the protection diode at the input of the ETCS (protecting the system) but it also suffered damage from this event and will need repaired or replaced.

You have a DMM, yes?

 

Yes the friend helping me with this does but he's only had about 15min to look at it. But I do understand what your saying that's why I need to look at wiring schematic to figure out what that fuse powers the ETCS fuse powers so I can start working my way through and finding the actual problem. I understand the white wire with blue line isn't the problem now. And let ya know I appreciate how on top of this you've been talking to someone who is electrically illiterate can be frustrating. And I apologize.

 

I was able to get ahold of some but it doesn't go far enough I need what's after the red arrow

 

Calling it like it is, helps (frustrating). So I hear ya. We'll do what we can.

If you get a chance buy a $20 hand held meter thats does volts and ohms. It doesn't have to be Fluke just something that works. Also grab a 12v test lamp. You will need them and they will pay for themselves.

 

FWIW I can't read that. Its all blurry.

 

Any updates?
OP - you might follow this one and see if it helps you.
https://www.clublexus.com/forums/is-...ode-p2118.html