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this is how i fix my car idk if this will help someone but its more info on IACV problem

so in 3 month ago i bought SC400 and the car will stall on start you need to put your foot on gas for some time after that the car will idle but very bad and if you put it in reverse it will stall previous owner told me its IACV problem so i did replace it with 4 different iacv all of they did the same of stalling the iacv was stock close and i did rebuild the iacv and i put the iacv to open position and install it and the car run good for 2m and stall and keep going in close position so i try replace TPS MAF did not work so i remove them and install OEM MAF TPS

so now i will tell you how i fix my SC4 and diagnosing it with pictures

i did use LED Test light like this (dorman 86602)

connect RED to + black to - and the test light needle to IACV terminals so IACV have 6 pins 1 2 3 so number 1 3 4 6 is ground and 2 5 is power and you test 1 3 4 6 and test it and start the car and i should start to light when car is off its will be green when you start is it will flash red
4 5 6 see image below
and it will be sold red and it will flash green a little bit see image and i have videos of it on youtube

used needle and connect alligator clips to it

connect iacv plug

car is off but connected to battery






now i know its not iacv issue 4 has been replaced and mine was rebuild
no i did test and setup my TPS


you can check video on how to set up TPS by kelvin CartuneNZ
after setting up TPS i test my IACV wires and ECU for signal using halogen bulb see this video i used this turn signal light

now you need to plug this bulb to iacv terminals like this use terminal 1 and 2 and start car and it the bulb should light and not test terminal 2 and 3 bulb should light now 4 and 5 bulb should light and not 5 and 6 if all work that mean its not the wire harness or ECU





no check this youtube video on how the bulb was flashing on terminal 1-2 and 4-5 and 5-6 but did not flash on terminal 3 see video
now the problem is ECU or the wire harness from ECU to IACV
i test the wire harness so from ECU and IACV side
ECU side is 32 and IACV side is 3 as you can see in image so ground terminal 32 to and with a test light Circuit Tester with filament not LED and after grounding terminal 32 i need to plug the test light to the+ battery and plug the test light to terminal 3 on IACV if the test light did not light that mean the wire harness is bad on terminal 3 or 32 or in between or if it did flash as you see in image that mean ECU is problem

dont forget to disconnect battery and removing ECU when doing this after ecu remove and you need to test the wire you can plug battery back

this is terminals of iACV and ECU B1 B2 is power and S1 S2 S3 S4 is ground



you can used the bolt you see in image for ground


connect test light to +


now i know its my ECU is bad if your asking your self why i did not just check ECU Capacitor before, its because of the ECU was from flagship one and i did not want to remove the warranty on it before i can talk to them and see if i can get replacement i did not replace it so i bought one form SC400 1992 and its california car and mine is not ecu number is not similar bud i did work and ECU was for 100$ and it was rebuild ecu from tanin auto electronix






this what Capacitor look like and not just my IACV not working my check engine light wasnt working at all

last thing check this video by CartuneNZ on IACV rebuild with part numbers

You Tube