2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

what the hell does this do? (wiring)

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Old Jan 28, 2006 | 01:50 PM
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From: warner robins, georgia
what the hell does this do? (wiring)

on one of the plugs to the computer... the one that is by itself... i think the big one, not the two smaller ones that are on the same big harness... there is a yellow wire and a yellow wire with a blue stripe that go off by themselves and get jumped together through what looks like a jumper block or a fuse or a relay or somethin.... anyway what the heck is that? its an s4 car. all my buddies with s4 cars and my T2 car i got for the swap to n/a has it... but my car (86 base n/a) doesnt... but there were some wires hacked up and re-done at the computer so im thinkin whatever it was has been cut out.

also... there a black wire that bolts to the tranny (not the ground wire that goes to the firewall) but it bolts right by the slave cylinder but its got like a little risistor? or fuse? box or something conected to the ring terminal that bolts it down and it connects at a connector. again, my car does not have this but all other s4 cars and my parts T2 car has this. like i said the wiring in my car was hacked a little when i got it....

WHAT DO THESE 2 THINGS MENTIONED DO???? thanks..
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Old Jan 28, 2006 | 01:53 PM
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From: warner robins, georgia
if i need to get pics of it let me know and ill go snap some of them, unless soemone knows what they are
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Old Jan 28, 2006 | 01:59 PM
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The slave cylinger black square thing is a capacitor for the oil sender unit.
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Old Jan 28, 2006 | 02:03 PM
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From: warner robins, georgia
ooh ok... lol so do i need it? my oil pressure reads about 60 at idle and 110+ at throttle (motor is rebuilt and someone told me thats normal if it has mazda racing pump in it)

oh yeah, and i found another one of those 2 wire things on the other 2 plugs that go to the computer. same type thing only the 2 wires on this are green with black stripe and the other one is blue with orange stripe... and again they get jumped together through some little plug in box./???

so what do these jumped wires do on the ecu plugs?
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Old Jan 28, 2006 | 02:14 PM
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yes you need it for the oil pressure gauge to work as it was designed to.

the brown plug you referred to at the ECU is a diode, it is like a one way check valve for voltage, leave it as is, it is supposed to be there.
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Old Jan 28, 2006 | 04:12 PM
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Welllllllllllllllll, if your talking about the diode for the ASV circuit, you got a few things wrong. It is tied to the middle plug, not the largest plug, and the wire colors are blue with a orange stripe and light green wire with a black stripe. Other than that, your description was perfect.
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Old Jan 28, 2006 | 08:53 PM
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From: warner robins, georgia
lol so what does it do? and do i realy need them becuase my car doesnt have them
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Old Jan 28, 2006 | 09:19 PM
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this is a rather confusing post, try listing what wiring harness you have and which motor you are installing with this harness and what type of car it originally was.
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Old Jan 28, 2006 | 09:26 PM
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From: warner robins, georgia
its an 86 base. 5-speed. nothing changed all stock wiring. im not installing any motor ive just noticed in al the junkyard cars and al lmy buddies cars and all my parts cars the wiring to the computer has these but mine doesnt. someone before me put a rebuilt motor in. so obviously they cut these out for whatever reason. just wondering what they do
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Old Jan 28, 2006 | 10:02 PM
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From: FORT WORTH, TEXAS,USA
Originally Posted by matts86fc3s
lol so what does it do? and do i realy need them becuase my car doesnt have them
Here, let NZcOnVeRtIbLe tell you from this thread: https://www.rx7club.com/forum/showth...ighlight=diode

Are you putting a turbo harness in a n/a or vice versa? Or? On the whole, if you don't have pwr steeriing, you could get by without it. If you look at page 50:22 of the series four wiring diagram you can see that diode coming off pin 2M of the ECU.

No pwr steering.........forget about it being there.
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Old Jan 28, 2006 | 10:42 PM
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even my T2 that wasn't equipped with power steering has that diode, my guess is just for the universal wiring harness as it has the power steering plugs up at the LF strut tower so even a car not equipped with the diode should have it there still, but this is a moot point if it doesn't need it.
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