Hello all am desperate, I bought a auto-dim rear view mirror from ebay for my Lexus IS250 2012 and I had the car running when I was connecting the mirror, i thought something was wrong because the male and female harness does not seem to match perfectly with the female harness on the mirror which has around 6 pins and the male harness on the car which only has 2 pins, i still proceeded to connect them and immediately the my AC unit shutdown, steering light, abs light and traction control or ESC light is on, the shifter to put in drive is locked and can only be moved if i press the shift lock button and the steering wheel is STIFF, I have techstream and capture the error codes, please please please help if you can

 

Look in your user manual at all of the fuse description of use (it has more detail than fuse box lids), and find which fuse branches to each of those items. Replace fuse and should be back in business.

I'm guessing it's a cabin fuse that took a hit. Likely the body control module (BCM).

 

I will check as you suggest and update right away, Thanks for taking the time out of the day to offer some help, much appreciated.

 

NP - it should be simple fix once you see what they share in common and then go find that fuse and pull it for examination.

I suggest you take a picture before starting so any empty spot doesn't get filled accidentally.
Post up if you need to know some terminology.

 

Hello, so my mechanic tested all the fuse both inside under the driver side, under the passenger and both in the engine bay, i used a multimeter tool and check connectivity on ALL the fuse and all beeped, I do not have a wire diagram of this car, just a user manual. I will note that when I run the techstream I am getting an asterisk next to the AC air conditioner as in the module is not being seen, the U0123 and U0124 are the only codes that remains......I am so frustrated.

 

Sorry man, but using an ohm meter on a fuse wired to "devices" will give you a false reading. It it will not always detect an open.

Do what I suggested and look up the 10 most likely suspects and pull them and look.

The only way to use a meter in this circuit to find an open is using it in Volts mode (car must be on for this), and for example, if testing a headlights or turn signals, those switches would need to be on, otherwise it would fail the test. Anyway, a good fuse will show zero volts. An open fuse will show battery voltage. Your mechanic appears to need a new lesson in troubleshooting.

I'd suggest you tell him to redo test for free, but start with owners manual as I suggest.

 

Hello again, I appreciate your time and brutal honesty, keep it coming. As you request i pulled more than 10 fuse and found 1 broken fuse under the passenger side as shown in attachment (10A ECU-IG LH), all fuse under both the driver and passenger side all the fuse had continuity and a 0.2 - 0.3 Ohm resistance, I even went in the engine bay with the same results. I replaced the broken fuse with the same ratings but no change in my problems, all the lights that was previously on such as steering, ABS, traction/stability are still on as shown in pics below, I even went into techstream and did a health check on all 28 ECU but u0123 & u0124 remains as shown in pics below. If you also noticed the Air conditioner and park assist module has an asterisk which denoted the module is missing, you can correct me if im wrong.
Shows the lights on dash

No lights on A/C module

Fuse that was blown ECU-IG LH (Fuse was replaced with same rating)

Blown fuse

Message when I try to ruin my A/C

No reading for outside temperature

When I do individual health check on park assist

When I do individual health check on Air conditioner

Asterisk showing modules are missing ?

 

Forgive me if this is a double post I may have forgotten to mention some info on previous post if it was indeed posted (still getting use to CL). First of all thanks for your time, knowledge and brutal honesty, I do appreciate it. As you suggested, I pulled not just 10 likely fuses but basically all and tested for continuity and resistance and I found 1 broken fuse as seen in pic below

Pic of broken fuse (10Amp)

ECU-IG LH (location of broken fuse) Fuse was replaced from spare (10Amp)

I will also add that all other fuse from passenger/driver/engine bay (No relays were tested) had continuity and a resistance of 0.2 -0.3Ohms.
After doing my fuse checks and making sure all fuses went back in the correct location and were properly seated I proceeded to start the car but the results were the same, all previous lights remain, steering/ABS/TRC or stability light, steering wheel remains stiff and still unable to move shifter without pressing the shift lock button,
Next I went into techstream and ran a health check on all 28 modules and results were U0123 and U0124 remains, I tried to clear but they still remain.

Asterisk next to modules that indicates they are missing or not being seen

Individual checks of module with results as shown

Individual checks of module with results as shown

Message on screen when I try to operate my A/C

No outside reading of temperature

A/C controller does not light up, radio works, navigation works (pretty much everything else)



These are the lights displayed on my cluster when i start my engine before and after broken fuse was located (same results)

 

So what did you find out?​​​​

@Danis250268

 

Yes sir, not sure what's happening but I posted a reply on the tread and am guessing admin has not approved it? Anyway today I got the problem sorted, turns out there was a "bad relay" and the shop also "reprogram the ECU", they are very secretive so i don't have details... My car works as it did some days ago and I'm happy but i would have love to get the details of the fix

 

Given the cause and effect, I personally would call BS if they can't test a fuse properly. If your post had tmi about bootlegging techstream, that will get it deleted. Post again.

 

Well I made a post which was quite detailed with pics and illustrations but for some reason it was not approved I guess so ill just do my best with just text and omit a few words or names that may have probably flagged my post.

After your above instructions I went back on my own and did some physical inspections of the fuses in the the cabin where I tested for continuity and resistance and found one damaged fuse, it was the ECU-IG LH fuse on the passenger side box (Right hand drive) 10A fuse, coincidentally that fuse was over the A/C, Power steering, ABS, ESP. Shift-lock, all of which I was having issues with. I replaced that fuse with correct and exact rating but no change. I went to try and clear the U0123 and U0124 with a "certain software" that i wont mention and the DTC code still remains, I tried leaving the battery terminals off for 1 hour, no change.

My next step was to take it to another technician that was mentioned to me, I explained to them my experience and my own trouble shooting and left, 5 hours after i returned and my car was completely fixed, everything worked as it should, no codes, nothing. I asked what the fix was or what the problem was and I was told I had a bad relay and the had to reprogram the ECU and that was the end of the explanation. Drove my car hard on my way home to make sure it held together and to this day i am having no issues at all.

 

I suspect there was a another fuse taken out somewhere. Relays on these things are very reliable but there is a chance it died if it was in the path of short circuit but thats not how they wire these typically. Q? Did it pop your new fuse, ever?

Glad it's fixed. Did they say what they reprogrammed?

 

What they said to me is that they reprogram the ECU, from my understanding i believe that this car has like 28 of them? or is it different from BCU ? they were just vague and i was not about to play 21 questions but I will be monitoring my car for the next few weeks.