300ZX (Z31) Forums Dedicated to 84-89 ZCars otherwize known as the Z31's

Trouble code 14 speed sensor

Old Jun 2, 2016 | 01:01 PM
  #1  
jeffro's Avatar
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Trouble code 14 speed sensor

Hey. I have an '85 turbo m/t that started acting up recently.
Starts good idle 700 will accelerate through 1st gear fine
But after shifting into second it loses all power and gas pedal
Becomes useless, as in press pedal engine dies. I pull over give
It a minute or two then it fires right back up and drives normal
With WOT.

Two weeks later happens again on the weekend so I pull the
Computer to run codes. Gives me 31(Ac) and 11(cas). So I pull the dizzy check connections. The cas pigtail had a little corrosion so I cleaned it.
The coil looked pretty gnarly so replaced that, cap, rotor plugs and wires.
Also picking up prw2 ignition control module today to swap in.

Ran good for about a week then back to stalling on acceleration. Ran trouble codes again and pulled cas, afm, speed sensor and ignition signal codes.
So I pick up a new (reman) ecu. Reran codes only got 31 and 14(speed sensor) on the old ecu and ran codes again on the reman ecu and pulls the same codes
31 and 14

I read somewhere that if your speed sensor is sending faulty codes it can make the ecu think your going 137 when actually going 20. My question is; If I cut the purple wire at 29 (speed limiter) would this work long enough for me to get it to a buddies house to lift it of the ground?
I also have the digital dash if that makes any difference in trouble shooting the speed sensor. On that note the speedo works on the dash and is somewhat accurate (due to non stock wheel size)

Any help greatly appreciated thanks!
Old Jun 2, 2016 | 07:14 PM
  #2  
rogerz's Avatar
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Joined: Sep 2006
Posts: 1,415
From: Mill Creek WA
if it revs fine in the drive but bogs when driving speed sensor. had the same problem on my 85T that I gave to my son. cut purple wire #26 going to the ecu. Double check me with the schematic but that will cure the problem. of course now you will be able to exceed 135 mph which might garner a ticket, Otherwise if you are electrical genius you can go into the speedo and check the sensor.
Old Jun 2, 2016 | 11:34 PM
  #3  
jeffro's Avatar
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Cool cool thanks man.

What would work best just snip and tape wires off, quick disconnects or interrupter switch for after fixing the sensor ( after I find one lol)
Old Jun 3, 2016 | 07:57 AM
  #4  
rogerz's Avatar
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Joined: Sep 2006
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From: Mill Creek WA
I just cut it and called it good. put a piece of shrink wrap over the open end.
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