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The mkiv Supra Owners Club

Stock ECU: Black Yellow wire


Jellybean

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Hey

 

Issue:

 

If a passenger was in the car and pressed on the footwell area the car would nearly cut-out, so I wanted to take a look before I headed up north for the 20th Anniversary

 

  1. I disconnected the battery,took up the carpet and found the ECU cover was loose; so I tightened up the two 10mm bolts! Put it all back together!
  2. Reconnected the battery and she was misfiring / Over fueling, Got Engine Code 31, took off the cover again and found the Black wire with Yellow strip was disconnected, re-connected , started and she seemed fine. Did a check of the harness , looked good.
  3. Put everything back together,
    • Car wont start,
      just cranks

    • Boost controller (Apexi AVCR)
      stays on

    • Engine light , stays on very dim
      and the symbol to the right of the door Open (looks like overheating symbol)

    • Slip cont is a Lime/yellow colour

 

 

Questions

  • The obvious, Any suggestions?
  • The Black wire with Yellow strip on the middle ECU block , from reading on here is a fuel pressure signal wire or airbag check signal; I didn't think this would cause a Misfire/ Over fueling?
  • I taught it might be the Alarm but the boost controller staying on etc put me off that idea

 

I had to stop working on it last night because it was 12.30 am and the exhaust is too loud. So I didn't try see if it has any new engine codes but the battery was disconnected and not too sure if the ECU will store any codes because it is just cranking and not firing.

 

Just looking for what the best way to tackle this and members experience of what I am seeing

Edited by Jellybean (see edit history)
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There are two black and yellow wires. One is the battery constant feed and is on the single plug pin 33A. The other in the MAP sensor signal and is found in the double plug with the bolt. Pin 62B So either the battery feed wire is being shorted or the map signal is open circuit.

 

Lyndon.

 

Thanks Lyndon, its the MAP sensor signal ; which makes sense the code 31

 

So is this incorrect?

http://www.mkivsupra.net/vbb/showthread.php?232824-J-Spec-Engine-Harness-Connector-Details

 

You don't happen to have a list of what wire colors are X signal?

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The dim dash lights also make it sound like you've got an earth fault. If a wire has fallen out of the plugs, it's entirely possible other ones are loose as well. You and your passenger footwell are about to become well acquainted :)

 

Also, kudos to Jellybean for a well written request for help :thumbs:

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The dim dash lights also make it sound like you've got an earth fault. If a wire has fallen out of the plugs, it's entirely possible other ones are loose as well. You and your passenger footwell are about to become well acquainted :)

 

Also, kudos to Jellybean for a well written request for help :thumbs:

 

Thanks Ian , its cramped down there! Not looking forward to it! :( I was getting very irate last nite lol

 

So would you suggest I start with the grounds , I can only see three pins on the schematic

 

  • Pin 69 ECM Ground
  • Pin 79 Power Ground
  • Pin 80 Power Ground

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she started fine and cut out after I put the ecu cover back on, took it off again and noticed the Japan wiring is not the best,Map sensor ecu wire need a solder, started fine again, the tested all the wires on the ecu by pressing/small tugs, working fine, car was still running, put the cover back on the ecu, car is spitting the petrol out the rear now, just cranking, no error codes

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Thanks Lyndon/ Ian for the help ; get her fixed, turned out the throttle position sensor feed wire from the boost controller was routed under the ECU retainer Frame; over the years the wire was getting crushed by the frame ; cut it out and re-soldiered , routed it safely away from anything. All working fine now.

 

Nice day over here yesterday, so took her for a pin to wash her , ready for a the 20th anniversary meet the weekend; was putting on the car cover to find a small stream of coolant ; Murphy's law, never had a problem with her in 6 years and 4 days before the anniversary everything is going lol I dont think she wants to see other Supra's

 

I think it is the seam weld were the OEM temp sensor goes into the rad is corroded , will get her on a ramp tonight so fingers crossed I can make it the weekend, If we have to, overnight parts from Japan ;)

 

Thanks again for the help

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