Last night while working on my Cruiser installing Owl Courtesy lights I noticed my Key Fob would not lock or unlock the doors. It was hooked up to techstream to make sure that the Courtesy lights would turn on when the doors open and unlock. Which they were set to on according to techstream. Well after finding out the my drivers side wiring was putting out 12 volts and my passenger only 4.5 volts I tied everything up and decided to take figure out why my Fob was not working. I am able to start and the door buttons work. I switched out every fuse I could think of. Tried leaving my key in the ignition in the on position for 30 minutes. Check that the sunroof, dome lights, and windows all worked. Nothing is working. I have another set of keys that I leave with my dad just in case so I will try that today. But what is odd is the keys red light illuminates when the button is pressed as well as the security light on the dash. This tells me they are communicating. Is it an immobilizer problem? I searched on here for a match to my issue but there is nothing that I could find that is exactly like what I am experiencing. I have not be rummaging around with wiring other than removing the AHC fuses. So I am at a lose. Any ideas?
Another Key FOB mystery. (1 Viewer)
- Thread starter Knowbuddy
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
- Thread starter
- #2
closest thing I could find is the following:
remote does not unlock or lock doors, but door switches do lock / unlock
I hope I do not have to replace the ECU...
remote does not unlock or lock doors, but door switches do lock / unlock
I hope I do not have to replace the ECU...
Trunk Monkey
Moderator
Start simple, new battery in fob.
We know.
It's an inside joke around here. Surprised no one has suggested it is your head-gasket.
Seriously, electrical gremlins are generally no fun. Hope your issue will be simple.
Do you have a DMM? If so, I can look in the Toyota Electronic Wiring Diagrams book as they normally have some troubleshooting steps with expected voltages and resistances given certain situations and inputs.
The wireless door lock/unlock function can be turned off via Techstream (default is on) in MY 03 LXs, can’t see your sig vehicle so may not be applicable, but it might be worth double checking.
And to clarify - wireless locking stopped working when connected to Techstream (definite possibility the feature doesn’t function when the body ECU is being accessed in a utility config mode) and works otherwise; or it’s not working at all even with Techstream disconnected.
And to clarify - wireless locking stopped working when connected to Techstream (definite possibility the feature doesn’t function when the body ECU is being accessed in a utility config mode) and works otherwise; or it’s not working at all even with Techstream disconnected.
- Thread starter
- #9
2004 LX. So they do not work even now when Techstream is disconnected. I got my spare Key this afternoon. It will not unlock the doors and wont start. So I am going to check out techstream in the morning. I also have a replacement batteries so I am going to try that as well.
Ok thanks for clarifying. A flat battery in your fob will limit/stop wireless locking/unlocking but won’t stop the vehicle starting (just removed my fob battery and started my truck, no problems) as long as the key is registered to the ECU. We will assume yours is. It’s something other than a flat fob battery.
- Thread starter
- #12
So just an update. I’m still trouble shooting but the dome lights are non functional. Which tells me it’s the ECU. I’m gonna leave it for awhile and not rush the repair. But from everything I’ve read yep it’s the ECU.
Have you checked the 10amp ECU B2 fuse in R/H footwell J/B? When blown that takes out a lot of systems and often the first noticed circuit not to work is remote locking.
- Thread starter
- #14
I haven’t thanks for suggesting that. I’ll try and report!
- Thread starter
- #15
You are a life saver. That worked! Which is a huge relief. I really appreciate you input!
No problem. When the ECU B2 fuse blows I’ve seen the following affected: remote key fob locking/unlocking; security light stops blinking; dome lights out; AHC won’t raise to H; wipers come on; remote mirror control; VGRS/VSC/ABS lights on to name just a few. Usually the first thing you’ll notice is, if VGRS doesn’t illuminate, remote locking stops working and if you’ve got your side mirrors set to auto dip on reverse they stop too. Lots of seemingly random things are impacted by the ECU fed via this fuse.
Last edited:
