# SR/KA Lower Harness Question, RE: Transmition Sensors **URL:** \ **Category:** SON240sx Automotive\ **Created:** [February 28, 2004, 7:36pm UTC](https://forums.speedlife.net/t/sr-ka-lower-harness-question-re-transmition-sensors/80637 "2004-02-28T19:36:52Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![SHIFT\_KA24DET](https://avatars.discourse-cdn.com/v4/letter/s/b9bd4f/32.png) [@SHIFT\_KA24DET](https://forums.speedlife.net/u/SHIFT_KA24DET)\ **Post date:** [February 28, 2004, 7:36pm UTC](https://forums.speedlife.net/t/sr-ka-lower-harness-question-re-transmition-sensors/80637/1 "2004-02-28T19:36:52Z")
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: 1. Neutral Position Switch 2. Reverse Position Switch 3. O/D (5th) Position Switch 4. 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. - Thanks ---
**Author:** ![MRWmotorsports](https://avatars.discourse-cdn.com/v4/letter/m/f14d63/32.png) [@MRWmotorsports](https://forums.speedlife.net/u/MRWmotorsports)\ **Post date:** [February 28, 2004, 8:34pm UTC](https://forums.speedlife.net/t/sr-ka-lower-harness-question-re-transmition-sensors/80637/2 "2004-02-28T20:34:11Z")
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 think I’ve got this mostly right… -Martin. > [@SHIFT\_SR20DET](#): > > 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: > > 1. Neutral Position Switch > 2. Reverse Position Switch > 3. O/D (5th) Position Switch > 4. 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. > > - Thanks ---
**Author:** ![SHIFT\_KA24DET](https://avatars.discourse-cdn.com/v4/letter/s/b9bd4f/32.png) [@SHIFT\_KA24DET](https://forums.speedlife.net/u/SHIFT_KA24DET)\ **Post date:** [February 28, 2004, 8:44pm UTC](https://forums.speedlife.net/t/sr-ka-lower-harness-question-re-transmition-sensors/80637/3 "2004-02-28T20:44:45Z")
According to this which I forgot the M/T has a 4th and 5th Switch… What do they do exactly and do I need them? ![http://membersdb.son240sx.ca/images/membersdb/1009_tranny_connectors.jpg](http://membersdb.son240sx.ca/images/membersdb/1009_tranny_connectors.jpg) ---
**Author:** ![MRWmotorsports](https://avatars.discourse-cdn.com/v4/letter/m/f14d63/32.png) [@MRWmotorsports](https://forums.speedlife.net/u/MRWmotorsports)\ **Post date:** [February 28, 2004, 9:04pm UTC](https://forums.speedlife.net/t/sr-ka-lower-harness-question-re-transmition-sensors/80637/4 "2004-02-28T21:04:33Z")
> [@SHIFT\_SR20DET](#): > > According to this which I forgot the M/T has a 4th and 5th Switch… > > What do they do exactly and do I need them? 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…). -Martin ---
**Author:** ![AnDrEw](https://avatars.discourse-cdn.com/v4/letter/a/f19dbf/32.png) [@AnDrEw](https://forums.speedlife.net/u/AnDrEw)\ **Post date:** [February 28, 2004, 9:15pm UTC](https://forums.speedlife.net/t/sr-ka-lower-harness-question-re-transmition-sensors/80637/5 "2004-02-28T21:15:34Z")
![http://membersdb.son240sx.ca/images/membersdb/1009_at_-_mt_wiring_issue_small.jpg](http://membersdb.son240sx.ca/images/membersdb/1009_at_-_mt_wiring_issue_small.jpg) Solution to your probs I believe… ---
**Author:** ![SHIFT\_KA24DET](https://avatars.discourse-cdn.com/v4/letter/s/b9bd4f/32.png) [@SHIFT\_KA24DET](https://forums.speedlife.net/u/SHIFT_KA24DET)\ **Post date:** [February 28, 2004, 9:20pm UTC](https://forums.speedlife.net/t/sr-ka-lower-harness-question-re-transmition-sensors/80637/6 "2004-02-28T21:20:28Z")
:thumleft: But where to plug in the Reverse Switch? The car srill won’t start. It thinks the car is not in Neutral/Park… Martin could you explain to me again how to fake the ECU on thinking the car is always in neutral. ---
**Author:** ![SHIFT\_KA24DET](https://avatars.discourse-cdn.com/v4/letter/s/b9bd4f/32.png) [@SHIFT\_KA24DET](https://forums.speedlife.net/u/SHIFT_KA24DET)\ **Post date:** [February 28, 2004, 9:28pm UTC](https://forums.speedlife.net/t/sr-ka-lower-harness-question-re-transmition-sensors/80637/7 "2004-02-28T21:28:49Z")
Bah… Found it the Reverse Lamp switch on the A/T models it’s on the Shifter Console so I tapped it in there and it now works… 🙂 But the car will not turn over… ---
**Author:** ![AnDrEw](https://avatars.discourse-cdn.com/v4/letter/a/f19dbf/32.png) [@AnDrEw](https://forums.speedlife.net/u/AnDrEw)\ **Post date:** [February 28, 2004, 10:13pm UTC](https://forums.speedlife.net/t/sr-ka-lower-harness-question-re-transmition-sensors/80637/8 "2004-02-28T22:13:24Z")
![http://membersdb.son240sx.ca/images/membersdb/1009_inhibitor_switch_bypas.jpg](http://membersdb.son240sx.ca/images/membersdb/1009_inhibitor_switch_bypas.jpg) 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… HOPE IT WORKS!! 😃