Speedo issues

[UNISA JECS]

91 240SX SE (w/H.U.D) originallu automatic

Ok having swaped my car to 5 speed I cannot get the speedometer to read correctly it seems as though it reads double the speed im actually going. I've searched and yet to find an answer so im making this thread.

From looking at the FSM it appears that the wiring is virtually the same between auto and 5 speed so what gives?

Im thinking it has to do with the heads up display with a manual speed sensor.

Just for refference I have the following speed sensors:

S13 Auto VSS
S13 Manual VSS
S14 Manual VSS

All of the above speed sensors have 20 teeth on there pinion and there pinion diameter is the same, so im thinking that internally the S13 auto speed sensor is different and that is why casing is physically larger by a tiny bit.

Anyone figure this out yet?

[johngriff]

It can't be the HUD, I have an auto HUD in my car with a manual gearbox and it works just fine.

Maybe do you have both wire joined together? If you were doubleing the pulse to the gauge it might do this.

[UNISA JECS]

It can't be the HUD, I have an auto HUD in my car with a manual gearbox and it works just fine.

Maybe do you have both wire joined together? If you were doubleing the pulse to the gauge it might do this.

No I dont have them joined together however I am using a 5 speed lower harness and 5 speed ECU.

My HUD and cluster read just fine when I was auto BTW so I doubt it related to an issues with my cluster or HUD..

[johngriff]

I would try direct wiring just one of the speed sensor wires to the cluster input, just to be sure that the wiring is absolute.

[UNISA JECS]

I would try direct wiring just one of the speed sensor wires to the cluster input, just to be sure that the wiring is absolute.

I know for a fact that I have the yellow/blue and yellow/black wired soldered in.

I know this because if you try and use a 5 speed harness such as I did everthing does in fact connect into place making you believe everything is fine but all is not.

The oil pressure swith, the alternator dummy light, and the VSS are not automatically connected this you must manually cut and splice using the harness plug from yoru automatic harness to make it all really work adn be plug and play.

Before I did this the speedo read nothing at all and now it reads more than what the speed is....hmmmm

[johngriff]

So have you tried the different sensors?

The two wires just represent inverted readings of the same pickup/magnet combo inside the sensor. If the sensor was damaged internally bridging the two signals it might double the pulse.

I mean is the speed "exactly doubled" or just seem off?

I know you are paying attention to the teeth offset of the sensor, have you messed with the final?

[UNISA JECS]

So have you tried the different sensors?

The two wires just represent inverted readings of the same pickup/magnet combo inside the sensor. If the sensor was damaged internally bridging the two signals it might double the pulse.

I mean is the speed "exactly doubled" or just seem off?

I know you are paying attention to the teeth offset of the sensor, have you messed with the final?

No its doubled its way wrong and no I have not messed with the final drive.

[UNISA JECS]

Im gonna try another S13 5 speed sensor that I have.

[UNISA JECS]

Below:

The plug you see cut here is from the manual harness and you can see where I spliced it into the auto connector so that its plug and play:

http://i167.photobucket.com/albums/u159/zilvia_album/KA24DET%20BUILD/P1010026.jpg
http://i167.photobucket.com/albums/u159/zilvia_album/KA24DET%20BUILD/P1010026.jpg

Below:

You can see the auto harness which I spliced teh 4 wires into:

http://i167.photobucket.com/albums/u159/zilvia_album/KA24DET%20BUILD/P1010003.jpg

Another pic showing where all this wire go inside the harness:
http://i167.photobucket.com/albums/u159/zilvia_album/KA24DET%20BUILD/P1010023-1.jpg

[UNISA JECS]

Information
Vehicle: S13 coupe KA24DET
Trans: S14 manual trans w/s13 VSS

Ok im getting fustrated with this shit..lol...well I tried two different s13 speedos and same shit they read high example at 2k rpm its about 35mph in 1st gear, however when unloaded up in the air at 3k rpm the speed is 15mph.

Im starting to think that shaft inside the tranny that the speed sensor is driven from os different between S13 and S14 manual trannys, I say this because I have measued all S14 and S13 speed sensors and all the pinions have the same amount of teeth and are teh same exact diameter. So im thinking the shaft in side the tranny that drives the speed sensor may be different diameter then the S13 shaft or the plastic pinion in the tranny that drives the speed sensor.

I know there gotta be someone that has owned a S13 KA24DE auto and has swaped in a S14 manual tranny out there.

p.s. BTW thanks johngriff for your help earlier :)

[BenArtM80]

I just finished the opposite swap, s14 ka auto swapped in an s13 manual tranny. All I've found is that the transmissin speed sensor needs to match the wiring/ECU of the chassis, i.e. s14 trans in an s13 needs to use an s13 speed sensor, and vice versa. It sounds like you've tried both speed sensors though with no luck, so I'm not sure if that info helps at all.

Any chance you would want to sell me that s14 manual speed sensor?

[projectRDM]

Ben, I've got your VSS here. I even refrained from peeing on it.

Unisa, the transmissions are identical, the difference is found in how the sensor reads the signal.

[UNISA JECS]

Ben, I've got your VSS here. I even refrained from peeing on it.

Unisa, the transmissions are identical, the difference is found in how the sensor reads the signal.


Yea I know this now I looked up that last possible thing that I thought could be different which was the speedometer gear drive (located in the actual tranny) not the gear on the VSS itself and there are all the same S13, S14 SR and KA.

By the way it is fixed now I think it had to do with the brown connector up near the glove box under the dash.

[94_240sx]

Have you seen this thread?

http://www.zilvia.net/f/showthread.php?t=189165

This is how he fixed it. I guess you should give it a try too.

"Ok heres an update, I unpluged the ECU and pluged it back I also upluged the brown connector located under the dash just above the right corner of the glove back and pluged it back in and it started reading correctly aint that some shit but I think it had to do with the little brown connector, weird shit, thanks for your help everyone."

[UNISA JECS]

Have you seen this thread?

http://www.zilvia.net/f/showthread.php?t=189165

This is how he fixed it. I guess you should give it a try too.

"Ok heres an update, I unpluged the ECU and pluged it back I also upluged the brown connector located under the dash just above the right corner of the glove back and pluged it back in and it started reading correctly aint that some shit but I think it had to do with the little brown connector, weird shit, thanks for your help everyone."

Yup I made it...lol

[94_240sx]

Yup I made it...lol


Sorry. Didn't know it was you. Haha...

[UNISA JECS]

[quote=94_240sx;1995238]Sorry. Didn't know it was you. Haha...[/quoIts]Its koo, thanks 4 the help anyways

[dori_sil8t]

sorry man not to thread jack. but i have an 90 coupe with hud, im putn my sr into her shortly and my question is can i just use my sr cluster or do i have to use the hud unit and buy an aftermarket tech?
nvm i found it
http://www.zilvia.net/f/showthread.php?t=73947&highlight=hud

[BenArtM80]

congrats on getting it fixed

Russ, thanks for not peeing on the VSS for me

[g6civcx]

Swap out the gauge for a known good.