My car hasn’t been able to start for a couple months now and I’m still trying to figure out what’s wrong with it. The car unlocks and locks normally with the key, but when I press on the brake the engine start button lights up amber. When I try to start it, it goes into accessory mode and refuses to crank. When I try to start it with the key outside of the car, the car displays a “key not detected” message on the dash. I’ve already checked my key, brake switch, neutral switch, all fuses and relays I could find including the fusible link. I’ve also tried the truck where you unplug one of the connections on the ecm to see if it starts to test to see if it’s the fuel pressure sensor. Finally, I’ve replaced my battery, ecm (was reprogrammed to the car,)and PSCM. My reasoning for thinking that it could be the IG1 relay is because from my understanding, the engine start button only turns green when both ignition circuits have power. I also have no idea what else it could be so any advice or other theories would be greatly appreciated!

 

I also came across this thread where this Lexus owner had the same issue and it was fixed by replacing the IG1 relay. This is the main reason why I believe it to be the culprit and am trying to figure out it’s location


https://www.clublexus.com/forums/is-2nd-gen-2006-2013/934432-2008-lexus-is250-doesn-t-start.html

 

IG2 is located in engine compartment / driver side fuse box (#1 / 10 amp). Relay (R4 is IG2 relay). IG2 Main is located in passenger side fuse box near battery (# 4 20 amp). Unsure of IG1 Fuse or Relay location.


DRIVER SIDE BOX


PASSANGER SIDE BOX

 

Appreciate the response! Yeah I’ve already checked the fuse and relay for IG2, but I cannot for the life of me figure out where the really for IG1 is located.

 

So there is an IG2 in both panels above according to my car. The catch is IG2 MAIN by the battery w the fuseable link is IG2, IGN, GAUGE @20AMPS.

The other panel by the ECU is 10Amps and is just the ignition system.





Don't forget there are panels inside the cabin.
The left side has:
#12 ECU-IG LH 7.5A

Rightside:
#8 IGN 10A

LOOK in your owners manual. I'm using OM53B64U.

Edit; my bad I thougIt you were looking for the fuse for IG1.

Look in the cabin and maybe it is there? I don't have any pictures of those and the manual doesn't document what relays do what so a picture of the cover would be helpful.

 

I took my entire dash apart trying to find it but I can’t seem to figure out where the damn thing is. I know it exists because it’s mentioned in a couple wiring diagrams, but I can’t find anything on its location😭😭

 

Came across the following diagrams, Refer to item in YELLOW (photo 1 & 2):


F RELAY LOCATIONS [Cowl Side J/B LH Inner Circuit]



F RELAY LOCATIONS [Cowl Side J/B RH Inner Circuit]

 

Any idea how I would get to it?

 

Refer to the locations J74 & J75 (Body ECU Cowl Side J/B RH), referenced with a Black arrow in Diagram1
Refer to the locations Q1 Body ECU (Cowl Side J/B LH), Q2 Body ECU (Cowl Side J/B LH), Q3 Body ECU (Cowl Side J/B LH) referenced with a Black arrow in Diagram 2


DIAGRAM 1


DIAGRAM 2

 

Good job Elexis.

OP, they are not in the dash, they are in the kick panels to the side IIRC. I think each has a nut holding but pop right off.