For context, I am getting a 05 GX470 if I can get it running. It was running earlier in 2023. It was my In laws GX.
1) The car was over heating and so my FIL change the water pump and radiator and parked it. The GXwas gonna go to my MIL's Dad but has passed away before he could get it started.
2) Apparently all it needed was a new starter. It has 200kmiles on the clock.
3) When I got to it Gramps took most of the engine bay out (air intake, engine cover etc) all I had to do was take the Head off and change the starter.
After a great amount of learning but before I button everything up, I go for a test crank, nothing. The steering wheel comes out and does its thing, the radio, AC and clock are not holding memory and my dashboard is lighting up like the tree at times square. So I start troubleshooting I checked all the fuses, they're good. I changed out the starting relay, still nothing.
I called a bunch of mobile mechanics to come check it out, (they were kinda not into the idea but gave me some helpful pointers) one pointer was tp run a wire from the starter through the relay slots and and I got a crank. but where i kinda messed up is I didnt have the key in the "on position" so I think I tripped the Immobilizer.
What I need help with is should I change the ECU (becuase the clock, ac and radio dont hold memory) and should I change out the immobilizer? If so How do I change it out? (parts already ordered)

I just realized that I didnt check the junction box because only when I put the starter wires in a combination of slots, where the relay goes, do I get a crank. I do have techstream on a virtual machine and am getting trouble codes. Will post pics if anyone is interested. From what I understand theyre only bodycodes because My FIL changed the Rear bags to springs.

Mahalo in Advance

 

If you get a crank when you jumper to the starter lug, then mechanically it's fine.
I would also jumper 12v to the input terminal to the starter relay to verify the relay and wiring from there to the starter is good.
I would test all the fuses with an ohmmeter (the under-hood ones plus the cabin ones) to see if any are bad. Sometimes you can't see visually if one is blown.
Since it's been so long without power, it's possible the ECU has forgotten the immobilizer code from the keys. Try reprogramming them.

Chip H.

 

Got it will try double checking fuses and reprogramming keys. I only have the valet key would that suffice? I’m not sure where gramps had the key and I’m certain he can’t say (he passed) but would I be good with buying keys from eBay?

 

The valet key is no good for programming the immobilizer. You need one of the originals.

Chip H.

 

As far as the radio, clock and AC memory always dropping goes, would I benefit from changing the ECU?

 

Those usually lose their settings when the power is disconnected.

Chip H.

 

So I requested service from mobile locksmith, They both said there was no power to the OBD 2 port and were not able to make me a key. After some mid level interneting, I'm thinking I'll have to change the ECU, I have some tech stream scans that say I cant connect to the engine ECU. I do have an ECU and immobilizer on hand. Is there a certain way to change them out?