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Discussion Starter #1
Hi all!

This is my first post to the forum here so apologies if this is a repeated post.

I own a 1993 MK4 Supra 2JZ-GE auto and I have a check engine light.

Since it's OBD1, I was informed that I can jump paper clip to terminal E1 and TE1 and the engine light would flash a certain amount of times while the car is in ON position. This doesn't work, the light doesn't blink.

I also bought an OBD1 adapter for an OBD2 scanner and had no luck communicating here.

Does anyone know why I can't communicate with the ECU?

Also if anyone has a link/instructions on getting to the ECU that would be great. I'm going to trace the wires and check out the ECU to see if it's in okay condition.

Thanks!
 

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i recorded mark7m001.mp3
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You have it right with jumping TE1 and E1.

is it possible it’s not getting a good connection with the paper clip ?

absolutely sure you’re jumping the two correct terminals ?
 

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Master Shit Fixer
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Also if anyone has a link/instructions on getting to the ECU that would be great.
It's under the carpet on the passenger's side (assuming LHD car), under the glove box and under the passenger's feet. There's a black plastic cover that you remove with 2 nuts to see it.
 

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Mind if I do a J?
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Are you using an aluminum paper clip or steel?
 

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Discussion Starter #6
It's under the carpet on the passenger's side (assuming LHD car), under the glove box and under the passenger's feet. There's a black plastic cover that you remove with 2 nuts to see it.
Perfect will take a look. Thank yoj

Are you using an aluminum paper clip or steel?
I'm not entirely sure, it's just whatever the dollar store sells. I guess the conductivity is affected based on the material? Which is better?

Check your connection. I believe you can also try the port by the ball chiller incase you have wiring issues in the engine bay.
What exactly is a ball chiller?
 

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4 T's and an X
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I am having the same issue with my 93 n/a. Opened the ecu and found a capacitor is bad
248680
 

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The past 2 years I've seen a crazy number of the mkiv ecus have leaking capacitors. I replaced the caps on a couple I had with mixed luck. Its like we've hit the lifespan of those fish oil filled caps and they puke all over the boards.

Oh ooops time to go standalone.
 

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i'm having a problem with a mkiv that randomly idles very low. checked everything i could think of then finally got to the ecu expecting (hoping) for bad caps but nothing. looked brand new.
 

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From the land down under
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Mine idles slightly lower after ive driven it for an hour or so, and leans out badly the more I let it idle. Once driving, AFR's are perfect, so I am presuming that there is a leaky cap that is specifically for idle AFR's.

There is a local chap here in NZ that is very proficient at rebuilding 1990's toyota ECU's, for the cost of circa $250 NZD, which I feel is fair, but the more I think about it, the more I just want to buy a Link G4+ plug in, standalone ECU and not have to worry about chasing small niggles like this
 

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Glad I'm not the only one with that problem lol. My car also does it but rarely. This other car does it all the time. Idles fine then will drop and almost die for a couple min but the comes back up. Drives great, just idle.
 

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Discussion Starter #14
I got a newer ECU and replaced it in my car...solved all the problems! The old ECU I had had capacitor/resistor problems. The new ECU even got rid of this annoying whine from my fuel pump. She drives friggin amazing now! Doesn't drive rich either.
 

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Discussion Starter #15
So apparently your ECU can "look" okay but the capacitor itself could have failed internally. The capacitors cost like 4$ and you can get someone to do it or just yolo it your self. I sort of fucked my old one up by trying it myself lol

Good way to make sure is to test the capacitance across each capacitor and make sure its reading near the value it should be at (10 or 20% deviation based on the capacitor)
 

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Discussion Starter #19
Oh forgot to mention, clean your IAC. That makes a huge difference. The gunk builds up sometimes and causes major idle problrms
 
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