Speed Sensor Wiring

[skylinelvr]

I was hoping to get a little help, or at least a good start on my issue.

I purchased an S15 Spec S that was converted with an S14 SR20DET and tranny. I call her my Spec R/S (or S/R, not sure which way I like it better). I'll be posting a build thread once I get off my lazy @$$ and transfer my pics off my camera.

With that said, the speedo has never worked. The guy I purchased the car from, bought the car from his friend while in Okinawa. His friend was the one that got it converted, and doesn't actually know the full history of the car. I've done quite a few mods to the car already, but my next goal is to get the speedo working.

I know the S15 has speed sensors in the rear diff and ABS sensors in the front HUBs and the S14 has the sensor in the tranny. I haven't gone underneath the tranny to see if the sensor is in there (I don't even know where to look atm), but I do believe the sensor in the diff is connected.

Now what are my options with getting the speedo to work? Would I just try and connect the speed sensor from the tranny to the ECU (I have a Power FC D-jetro), or would I go off the rear diff and ABS? Or would I try and wire them all in together?

Anyone that has any experience with this mod, please chime in with any tips and tricks you may have.

[green_rs13]

yous cant just connect the gearbox speed sensor to the dash as one is square wave and the other a syne wave.dey is likes ying 'n' yang bluv.

do you have abs still? does it actually work?

the abs computer gives the clocks its signal.
the abs ecu is usually bolted to the s15 ecu in the passenger footwell behind the kick panel.

[skylinelvr]

I'll have to take a look. I don't have the stock ecu, as I stated in my post I have a Power FC D-jetro. I do have an extra box next to the ecu, which may be the ABS ecu.

As far as I know, the ABS works. The light will flash when I start my car, but doesn't stay lit while the car is running.

[skylinelvr]

So last night I decided to take a look in the dash to see if there was anything that looked out of the ordinary. Of course everything seemed out of the ordinary since I don't have much experience with wiring, lol. There was a ground wire that was grounded, but but wasn't connected to anything. I took the cluster out and discovered that the ABS light was connected to the oil light. It was done this way to pass an MOT. So I was mistaken in thinking that the ABS was working properly.

I'm now thinking that the ABS is what is causing the speedo to not work properly. I've checked the ABS ecu and as far as I can tell it's hooked up properly. The fuses were all good and I checked the ABS sensor in the rear diff. I'm not too happy with how the wiring looks on the ABS sensor, so I plan on splicing into it and cleaning it up. I know there are 2 other ABS sensors in the front wheel wells which I'll take a look at when I get some time. I did a quick look over of them and traced the wiring back through the engine bay and they looked ok. I'm not sure what else to check for the ABS.

I'm going over the texts that I received from the previous owner and he mentions that he recalls the diff not being hooked up. Is it even possible to not have the rear diff connected? If so, how would I reconnect it?

[green_rs13]

mate, if the diff want connected you wouldn't be able to drive very far!

test to see if the abs is working by doing an emergenct stop on some wet grass/mud/gravel etc.. if it skids it dont work if the pedal does funny things you have abs.

the abs ecu bolts to the ecu cage so if you have a spare plug coming off the engine loom near the ecu you dont have an abs ecu connected.most people would bolt the power fc into the ecu cage.

[skylinelvr]

I figured the diff was connected.

As far as the ABS ecu, I have a box bolted next to my Power FC that has 2 plugs going into it. To me that appears that the ABS ecu is connected. Now as far as having ABS, I'll have to give it a hard stop to find out.

[super_woody]

first of all not all s15s rand the abs from the diff
was only 6 speed versions aka most spec r's
the spec s is a bit diffrent some did or didnt have a abs sensor in the diff, most was in the 5 speed gearbox
also unlike the s14a the s15 goes abs sensor- then abs computer then ecu then too the clocks
first thing you want to do is find out if your power fc is for s14a or s15
then see if you still even own a abs computer
and start following that route

or you could cheat and just buy somthing like a digital dakota speed signal converter

[skylinelvr]

Thanks for the reply.

Once again, I have the ABS ECU and it is installed/plugged in. The Power FC is for an S14. Once I get my car up on a lift, I plan on checking to see if there is a speed sensor in the tranny and if it is connected. The tranny is from an S14, so not sure if the sensors are vastly different between an S14 and an S15.

[super_woody]

In that case your s14 ecu wont be converting the signal for the s15 clocks so you'll need a speed signal converter

[skylinelvr]

That's what I was figuring. Knew it wouldn't be as easy as just plugging it up. Where might I be able to get one of those?

I'm wondering if they already had everything hooked up, minus the converter. If so, might make my job a lot easier. Thanks for the help.

[super_woody]

drop the guys over at digital dakota a email

[skylinelvr]

Thanks for the tip.

I sent them an email and got a response pretty quick. They told me which one I should purchase, but the only thing is I need to keep the ABS disabled. Doesn't seem to be an issue since the ABS appears to be disabled anyways.

Are there any other converters out that would work with ABS (that's if I ever figure out how it was disabled)?