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Both 2 gear and L gear lights on at same time, Random MANU light, Auto Lockout

740 views 5 replies 2 participants last post by  supra-raleigh 
#1 · (Edited)
Car is stock with 215k miles and is a 94 Turbo model. I have the random manu light with automatic shift lockout. This is coupled with another strange phenomenon in which both green lights on the dash under the tachometer for 2 gear and L gear will illuminate simultaneously if the shifter is in either the 2 or the L position. I have read several posts and none resolved the issue. Wiggling wires under the shifter did not help. Disconnecting the manu connector did not keep the manu light from turning on randomly. This is not the blinking manu light issue. I am sure someone has the answer here. My best guess now is a fault in the ECU that controls the transmission. Any thoughts are welcome.
 
#4 ·
The problems never came back. But, I think that the ECU I have in it now, which is my refurbished original ECU, has had a capacitor failure or some other issue because the Intake Air Control Valve (IACV) has developed a malfunction. I have the IACV electrical connector disconnected because it was operating very erratically.
 
#6 ·
I then removed the IACV and put it on my other Supra, which is a 98. While it was on the 98, I let the car idle and heat up to where the RPMs were where I wanted, I also tuned on the a/c so as to raise the idle a bit. And with the RPMs around 750-800, I disconnected the IACV electrical connector while the car was running. The thought is that the IACV uses a step motor that I believe will be stuck in that position that it was last in immediately before the connector is disconnected.

Then I transfered the IACV back to the 94 and left the electrical connector disconnected. The 94 idles at 750-800. On cold starts, I will give the car a little throttle to compensate for cold start idle up which is supposed to be controlled by the IACV.
 
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