'95 speed sensor reads too high

[Kevin S14]

I just picked up a '95 240sx, and the previous owner attempted a 5 speed swap. He got it in and running, but cut up the harness so none of the plugs were left on the engine harness. Also, I believe the car still has the auto ECU.

Looking through the FSM, I found the red and red/yellow wires, and connected them to the sensor. It works, but reads twice as fast as I'm actually going. I believe the trans is out of an obd2 car because the crank sensor is in the top of the bellhousing, but I don't know the year of the car the trans came from.

So my question is, Is there supposed to be a resistor somewhere in the circuit that I'm missing? Does the OBD2 speed sensor read differently in a '95?

[Kevin S14]

Anyone? Anything?

[sx moneypit]

You need to look in the auto to manual conversion threads,you should be able to get your info there.

[Kevin S14]

I've spent hours looking for an answer to this in about 10 different swap threads, and nobody mentions anything about this problem. Everyone just says "The sensor will just plug in" and doesn't offer any more information. I didn't have the option of just plugging in the sensor since the dumbass that had the car before me cut up the harnesses.

[sx moneypit]

You might want to source a uncut harness and do away with all the cut up bulls**t.

[diggles240]

If the speedometer reads twice as fast as it should, the speed sensor is from an s13. Is the speed sensor on the transmission metal or plastic? s13 speed sensors are silver metal with a pigtail and s14 speed sensors are black plastic with no pigtail. If yours is metal, source a plastic s14 speed sensor. Keep in mind that the pinion gear and retainer clip are usually sold separately from the sensor itself. Also, '95-'98 transmissions are all identical (having the CKPS on top of the bellhousing), so you simply need an s14 speed sensor. It is perfectly acceptable to use the Auto ECM. However, do not connect the 5th position switch when using the Auto ECM as the matching pin on the Auto ECM is for on-board diagnostic purposes.

[shiro_neko]

yes it might be a wrong speed sensor or its defective: 240sx-speed-sensor-tutorial-t393740.html

also if you changed wheel sizes the speedo would need calibrating. not sure if its the same with digital speedo

[theboz]

I just got through with my 5 speed swap. The speed sensor from the auto transmission had an off yellow colored pinion gear. The manual transmission speed sensor had a red colored pinion gear. The cut of the teeth were different and this would affect the speed reading to the car. The red pinion gear was all chewed up on mine so I went to the Nissan dealer and ordered a new one. Took 2 days to get in and cost me $22. Works fine. I kept the auto ECU. Everything works fine and the governor is no longer in effect on the car. Did the same thing on my S13 before I went to SR20 also.