View Full Version : ka speedo to SR tranny
Colin1337
06-07-2009, 08:40 PM
i heard theres a way to wire this so the speedo works?
i tried to search, went 10 pages in tech talk, and came up with nothin.
if this has been covered, point me in the right direction, and the mods can delete this.
thanks!
kevmeistah21
06-07-2009, 08:42 PM
i believe you can use a ka24de speed sensor for an SR and here's my illustration if you wanna hardwire your speed sensor straight to your cluster. good luck
http://zilvia.net/f/s-chassis/248941-hardwire-speedsensor-cluster.html
mestizo
06-07-2009, 08:53 PM
Get the apropriate speed sensor for your chassis, so if you have an S13 then use your stock speed sensor in the SR. I have an S13 VSS in my S14 SR tranny and it works perfect. However the automatic S13 VSS won't work, Im not sure about an automatic S14 VSS tho.
Colin1337
06-07-2009, 08:53 PM
sweet, thanks a lot. im gonna have to do this when it gets out of the shop.
i noticed you said its "pretty" accurate? how much of a variance is there?
don_bagz
06-07-2009, 09:13 PM
ka speed sensor works on sr as well.. heard they have the same tranny structure other than the bellhousing.. don't qoute me on that tho..
Colin1337
06-07-2009, 09:21 PM
hmm, well then im assuming the dude who sold me the car either didnt hook the sensor up, or took it out for whatever reason.
kinda a shotty job all together, reverse lights werent hooked up either.
mestizo
06-07-2009, 10:23 PM
sweet, thanks a lot. im gonna have to do this when it gets out of the shop.
i noticed you said its "pretty" accurate? how much of a variance is there?
Im not sure if youre referring to me or not but my speedo isn't off at all. Basically because nothing has changed from a sensor stand point, only the motor/tranny changed.
don_bagz
06-09-2009, 10:01 AM
hmm, well then im assuming the dude who sold me the car either didnt hook the sensor up, or took it out for whatever reason.
kinda a shotty job all together, reverse lights werent hooked up either.
if its not running, maybe its not hooked up.. if it is hooked up and still not running.. try taking it out and see if the pinion is worn out..
Colin1337
06-09-2009, 02:23 PM
Im not sure if youre referring to me or not but my speedo isn't off at all. Basically because nothing has changed from a sensor stand point, only the motor/tranny changed.
ahh ok, thats what i thought. just double checking.
Colin1337
06-09-2009, 02:27 PM
if its not running, maybe its not hooked up.. if it is hooked up and still not running.. try taking it out and see if the pinion is worn out..
alright, ill check it out when i get the car back thursday.
i dont know crap about VSS stuff, but if for whatever reason it isnt there. is it as simple as plugging one end into the cluster, and the other into the transmission?
mestizo
06-09-2009, 02:38 PM
The VSS has to be in the tranny otherwise you would have a big hole where all the gear oil would leak out of. But yes it's pretty much just plug and play, if it's an S13 then the VSS has a 2 wires that are about 2 feet long with a plug on the end of it, this get's plugged in up by the front of the tranny.
Colin1337
06-09-2009, 05:03 PM
The VSS has to be in the tranny otherwise you would have a big hole where all the gear oil would leak out of. But yes it's pretty much just plug and play, if it's an S13 then the VSS has a 2 wires that are about 2 feet long with a plug on the end of it, this get's plugged in up by the front of the tranny.
the car originally had a SOHC ka in it, i see a lot of dudes who do SR swaps putting the DOHC cluster in? would i need to get a DOHC cluster?
pretty n00b question i know
mestizo
06-09-2009, 05:06 PM
DOHC cluster is for the tach not the VSS, because the SOHC has a diff signal output than DOHC KA's and SR's.
Colin1337
06-09-2009, 05:11 PM
ahh ok, well the tach works so he must have swapped the cluster.
i know what plug your talking about on the tranny, but if for whatever reason the car doesnt have the wires where should i go about getting those? junk yard obviously, but anywhere online?
mestizo
06-09-2009, 05:20 PM
The wires are in your harness and on the sensor, so you need to find which part of them is missing. Get an FSM and do the VSS trouble shooting section and you can find out what part is giving you a headache.
Also on a side note does you have a HUD gauge cluster?
Colin1337
06-09-2009, 05:26 PM
The wires are in your harness and on the sensor, so you need to find which part of them is missing. Get an FSM and do the VSS trouble shooting section and you can find out what part is giving you a headache.
Also on a side note does you have a HUD gauge cluster?
alright. the plug might just be stuck somewhere. i only briefly looked while the car was on the lift at the trans shop. ill look more in depth when i get it back. the guy i bought it from had the harness professionally done, so ill ask him about it.
hell, the guys at the shop may have even saw it and hooked it up.
no it isnt a HUD cluster
Colin1337
06-09-2009, 05:48 PM
so i talked to the dude i bought the car from. he said he tried to figure it out when he had the car. plugged his cluster into his buddies car who has a jdm cluster and it didnt work.
could it be that the speedo is just broken?
or does the jdm cluster use a dif plug or something?
guess all i can do is hook it all up, if it doesnt work, buy a new cluster =/
mine 5mph off in 5th gear and i have a s13 speed sensor in my sr
johngriff
06-09-2009, 11:56 PM
hmm, well then im assuming the dude who sold me the car either didnt hook the sensor up, or took it out for whatever reason.
kinda a shotty job all together, reverse lights weren't hooked up either.
DING DING DING!
Speedo not working, plus no reverse lights is a sure sign of a not hooked up lower harness.
The lower harness hooks into the speed sensor, reverse light sensor, starter, alternator and maybe a few more I can't think of right now. It is located on the passenger (US) side of the engine bay, between the engine and strut tower. You can see it connected from either the starter or alternator to the wiring harness bundle.
Following this harness towards the back of the car, you should find a small grey two pin connector for the speed sensor (a male and female, or M+F Connected) and the wires leading back for the reverse switch on trans, 5th gear switch on trans, and 4th gear switch on trans. Make sure these are connected. You can hard-wire these, inverted and your equipment will still work fine because the switches in the trans is simply open/close.
Also, someone mentioned the KA trans being the same as the SR.
You are correct.
The trans are probably 90% identical parts, with some of the ratios changed up and the casting pattern for the bell housing changed to accommodate the change in engine mounting surface. You can actually swap bell housings between the KA and SR and even CA with no ill effects.
KiLLeR2001
06-10-2009, 12:45 AM
You use the speed sensor that pertains to your cluster. If you have a KA24DE cluster (mph), then you use the KA24DE speed sensor, if you have a JDM S13 cluster (km/h) you need to keep the SR speed sensor.
Colin1337
06-10-2009, 03:20 PM
awesome, im lovin all this info.
im stoked to get the car back now so i can get under it and figure this thing out
its a SOHC cluster, which is weird because the tach works, and i thought it wasnt supposed to? (correct me if im wrong)
i think im just gonna end up buying a 180sx cluster, then plug everything in. hopefully it will be good.
mestizo
06-10-2009, 04:42 PM
You can switch just the tach portion of the cluster with a dohc tach, also I have been told you can run a wire to make the sohc tach work but I don't know for sure on that.
ok well johngriff already answered your question so you shouldnt really pay any attention to anything after that. do you know if the prior owner did a 5sp swap as well? because that may also have to do with youo reverse lights not working.
heres what to do:
1} pop your hood and locate your lower harness soming from your fuse bloack running back and under the fuel filter, there should be 5 or 6 plugs on that harness
2} locate all 5 plugs on your tranny, if there are wires sticking out of your tranny and no plugs on then you wll either need new senseors or you need to get plugs from a juskyard and splice an solder everything yourself.
3} make all harness plugs and tranny plugs correspond.
4} located VSS and its plug. there will only be one plug on the harness that reaches that far and they should match.
5} plug everything in and trouble shot what doesnt work.
done with that part.
now to explain the VSS/Tach situation....
as stated before almost all S-chassis trannys are exactly the same, WITHOUT the bellhousing. so alll you need is a VSS for the corresponding year of chassis
s13 chassis - uses s13 vss regardless of motor/tranny combo
s14 chassis - uses s14 vss regardless of motor/tranny combo
its like that because you are still using the original tranny's ECU
as for the tach, quoting johngriff himself
The SOHC tach works on a Pulse Per Minute basis, like the vss. The tach signal is based on the 12v Single coil signal, creating a sine arc pulse of 4 12v pulses per 360 rotation.
The DOHC/CA/SR Tach works on the same premise of Pulse Per Minute, yet uses a signal that is less than 12v's. Because of this the pulses are not accurately read by the 89-90 SOHC Tachometer because the voltage of each pulse it too low.
so what that means is the DOHC/SR tach reads the signal differently to accomodate changes in engine layout, resulting in a change in HP/torque specs. Sooo you have to put in a DOHC/SR tach into a SOHC chassis/gauge cluster
johngriffs thread also helps you understand how all this works:
http://zilvia.net/f/archive-faqs/143755-how-wire-ca-sr-tach-signal-89-90-cluster.html
fuck i hope that makes sense...... feel free to ask if you have questions
You use the speed sensor that pertains to your cluster. If you have a KA24DE cluster (mph), then you use the KA24DE speed sensor, if you have a JDM S13 cluster (km/h) you need to keep the SR speed sensor.
that BTW is completley wrong
boosted_kouki
06-10-2009, 08:41 PM
hey, don't mean to hijack your thread, but i have a similar problem,
my speedo and odometer are both reading fast,about double.
its a s13redtop in a s14, has a SR vss atm, if i get a s14 KA vss, it should hook-up and work fine?
thanks
Om1kron
06-13-2009, 10:39 PM
DING DING DING!
Speedo not working, plus no reverse lights is a sure sign of a not hooked up lower harness.
I don't know how savy you are with 240sx's but the sr20det transmission (at least on the redtops) transmissions from my experience is they either do not have the 5th gear position sensor or the reverse light sensor in place. You will see a blockoff plate on the transmission which you can remove and add the sensor from your previous KA24DE transmission for the corresponding chassis and then wire it into your lower harness.
But it's not necessary.
My reverse lights do not work because I did not feel like installing the sensor and adding the wiring and troubleshooting it.
Shoddy or whatever, I just don't understand why the fuck you bolded the "reverse lights don't work" as a SURE SIGN the lower harness is not hooked up when that sensor isn't even present on most of those transmissions.
:duh:
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