No start, No mil present acc or run

[evor]

Ok so I have a wierd problem that I have never ran into I have a 1992 Lexus SC 400, the car randomly will let me start it, when it will not start there is no mil in acc or run key postions, I have been told that it could be the ECU malfunctioning, the reason for it not starting is no spark the fuel pump does turn on but the coils are not firing they do have 12v going to the coils. It happens every day I will go out in the morning and be able to start my car it will start as long as the check engine light is on and run fine, after letting it run for a while or driving it I will not be able to restart it, has anyone experianced this type of problem, or is there anything other than a bad ecu the would cause the check engine light not to light up when the ign is in acc or run, also what pins do I have to jump to get a code so the next time I can get it to start I can pull codes on it. Thanks I am new to the forum, the car, and the engine.

 

[evor]

so a update I dont believe its my ECU I did pull it apart today no signs of capacitors leaking or any other damage to it, I checked all the fuses again they were all good I checked the ignition relay under the hood and noticed there was no power for the coil side of the relay. like I said before the car starts and runs fine as long as a mil is present at start up, I did read earlier tonight how to check power at the ECU, I did have a problem earlier in the day where my key would not go into the ignition cylinder, I eventually got it in but i'm thinking the ignition cylinder may be going.

BATT = +12v all the time.
+B = +12v with key on
+B1 = +12v with key on
IGSW = +12v with key on

where are these pins located? I checked the efi relay with a test light there was power for the coil and the hot side of the relay, so i'm guessing my lack of power to the ecu is the igsw, I need to know how to check it though this is my first time dealing with a ecu not working properly. thanks in advance I'm a nub when it comes to ECU electrical but electrical in general im ok

 

[evor]

checked the codes today code 13 and 31 came up does anyone know where I can find the driver side bank cam sensor I couldn't find it, still the same problems im thinking that maybe the ecu has a bad ground random things will kick power back on to the ECU like slamming the door, hood, or trunk. if anyone has had this problem let me know because its annoying the hell out of me I will have good wiring diagrams tomorrow to check the grounds for the ECU

 

[inzanyte]

Help

I got the same exact problem. Did you ever get it figured out? If so, Help Meeeeee... Please.

 

[sideshow]

replace the efi fuse
also pull off efi relay and try to squeeze terminals tighter