For those familiar with the KA and or the SR tranny and for those
who are not, there are 4 plugs that connect to the tranny:
Neutral Position Switch
Reverse Position Switch
O/D (5th) Position Switch
Speedometer Sensor
Now my dilemma is my friend is converting his Automatic 240sx into a
5sp. He has everything complete but the harness. I went over to take a
gander at his issue and it looks to be quite serious. He has the Speedo
sensor plugged in correctly that was a direct connect. But we can’t figure
out were to plug in the other three sensors into the main harness. Now
the harness going into the ECU has no place for them nor does any other
part of any harness. On the parts car in which he took the stuff out of he
said it just plugged into the bottom of the relay box but I don’t see
anywhere to plug it into on his car. I am completely boggled. I just
thought those signals would go to the ECU but evidently I was wrong. My
main concern is why are the Neutral Position Switch and the O/D (5th)
Position Switch Needed? I can see why the Reverse one is and can tap
that into where it connected onto the Automatic Tranny but the other sensors?
We are really stumped and want to get this car on the road so realistically
are those sensors needed and what do they do exactly? Thanks for taking
the time on reading this all the help I can get will be greatly appreciated.
With the rest of the car being wired as an Auto, you need whatever an auto would have, in order for the car to start. Plus whatever else yu can get
Neutral Switch:
Unfortunatly the way the Auto is wired isn’t ideal for this. The neutral switch on the auto provides the signal for the starter solenoid which requires more current than the 5 speed neutral switch was designed for. I just jumper the connector (2 pronged nr. relay box, chances are the 5 speed switch would work fine for a while.
Reverse sensor:
Just splice and solder the right wires. You need this for your back up lights to work (useful to help avoid morons driving into you… only works occasionally)
5th gear sensor:
I’m doing this from memory, but I’m pretty sure the auto has a 4th gear switch… same thing, just splice and solder
Plugs:
You should use the plugs off the Auto tranny for any plugs where the 5 speed ones don’t line up.
I was going to point that you’d forgot the 4th gear switch, but it’s not on the SR only the KAs…
As far as I could ever tell they are only used for spped limiting, but I’ve read elsewhere of problems if you don’t hook tem up (I can’t think of any reason but…).
Solution to your starting probs…Has to do with inhibitor circuit on the AT cars. You need to bypass it out your getting no power. The neutral switch on the tranny become your inhibitor.
Follow the wires I spliced in your wiring diagram and you will understand. One goes to fuse box/ignition and the other goes to neutral switch…
