Speedometer reading backwards /not working. HELP???

[mrneg9]

I have a 1990 240 sx hatch back. 124,00 miles. It has your basic cluster guages.Everything worked fine until today. My speedometer needle went all the way around and dropped on the other side. Thats where it stayed. If I get the car up to speeds around 60 or so the speedo will go backwards for a moment going to 120, 110, 100 ,95 then it will just fall back down and stay to the right. Everything else works. Tach, odometer ect. Any one else have this problem that can tell me the fix. Thanks. DJ

[mrneg9]

No one ?

[mrneg9]

Well I received no replies as of yet. I searched many other posts and have not found answer to my problem. Today I drove about 30 miles to a junk yard that had a Gauge cluster for my 240. Paid 75.00 for it. When I came home I installed it and same thing every thing works but the speedometer needle is not. I again checked all my fuses inside and under the hood. Also jacked the car up and checked the plugs under the car that go to the transmission. All the wire were intact. Does any one else know where the problem might lie.

What the chance of having two clusters that are bad with the same problem ?

Thanks. D

[Johnsont]

its probly not your cluster i have the same thing that wrong with mine it the sensor on your transmission mit be loose or messed up check that out

[mrneg9]

Which one is the sensor? Theres about three different things that look like they could be a sensor. Thanks. DJ

[ZakinaS13]

The Speed Sensor is located on the bottom of your trans, should have a thick black wire wrapping around it. Around here they are $85 for a new one. Should fix your problem.

[mrneg9]

Well today I changed out my speed sensor. Changed the gear oil too as some leaked out. I put in a brand new beck/arnley 090-5004 speed sensor. My speedometer still does not work. The needle sits all the way to the right and goes up from115 to 95 when I get up to about 60mph in speed. As I go slower the needle drops right back down to the right again. Replaced the dash cluster now the speed sensor and still nothing. My odometer is now working off and on too.

Ive searched three different site with people all having the same problem but no one has received a straight answer on what the problem is. I'm getting pissed off enough I'm ready to put my fist through the dash cluster. I took the car out the other day and did a drift around a corner slamming into the next gear and the dam speedo started to work. Only lasted about 1 mile and then it dropped to the right again. What is going on ?

[s13-t]

re wire everything from the dash to the ecu then to the sensors. will take a while but it should work

[johngriff]

You have damage in the body harness from the front of the car, around the D side fender, in through the SMJ.

Speed sensor is just a magnet housed around 60 or so metal pickups grounded to the wire. It is a passive square wave signal. No magic or "digital data".

So, just tap one wire by the pass side loom, straight off the Speed sensor harness, run it up through the dash, to the cluster, clip the existing Speed sensor wire, and wire in your new lead.

It will fix the problem.

The symptom of the speedo you are describing sounds like a short against a power some where in the body harness.

[mrneg9]

There are two wires coming off the speed sensor. Your saying tap into one of them and run that wire to the existing speed sensor wire at the cluster ? Also how do I know which wire is my speed sensor wire at the cluster ?

[blueballa]

not to thread jack but man i have the same exact problem as you. i had a hud unit in my sohc that was working from time to time so i swapped it out to a analog cluster and i got the same problem. its just sitting to the right and goes up to 95mph from time to time. but when i let off the gas it just go back down to the right side. ive searched and searched and searched. ive done everything besides replacing my vss. but i believe what we got is a wiring problem. cause the vss does work once in a while. ( if lucky). does anyone know whats the route for the vss? from the cluster down to the vss unit.? help.. there has to be a answer.

[AX75F92]

Did you ever find the solution to this? Im getting the same problem

[JesterX18]

The wires you want to check run from the transmission up through the lower harness where i believe they run into the fuse box by the battery. From there they run into the upper engine harness and then through the firewall to the ecu. Then from the ecu there is a body plug that runs the wires up behind the dash to the cluster. Depending on whether you have the single or dohc the speed sensor may have different wire colors. You can get wiring colors and locations at <www.240edge.com> b4 condeming wiring make sure you test speed sensor and combo meter as they are much easier to check. Both test are outline in the 240edge manuals.

The speed sensor is the big sensor on the back of the transmission and it outputs ac voltage approximately .5volts ac when you spin it fast by hand. Youll need a voltmeter set on alternating current to test. the only other solution beside running a new wire to the ecu and combo meter is to probe the speed senor wire where it enters the ecu. probe the connector while its plugged in and have the speed sensor removed from transmission but plugged in . have a friend spin the sensor by hand while you measure voltage at the the ecu connector. If you aren't getting .5volts AC when the sensor is spun then your poblem lies between your ecu and the speed sensor. So the cluster wiring from the ecu is good. If your getting .5 volts AC then the problem is either in the ECU, combination meter, or your wiring in between the two. If you dont have .5 volts at the ecu connector then use the wiring diagrams and check the next easiest test point which is the fuse box by the battery. again keep checking for the .5 volts until you find where you are losing it. For component testing, wiring colors, connecotr locations and proper wires to probe refer to the 240edge as colors may be different depending on what engine you have. B ut like i said check the speed sensor and combo meter first. Then wiring... good luck and i hope this helps..

[Blitz671]

I have the same exact problem. Can someone help on how to fix this?

[91white_ka]

loose connector or bad ground

[Guappone240]

I sorta has a problem like this only mines opp. Mine sits a about 12-15 and won't move. I bought some custom gauges (yeah I know ) but I like them. Anyway I wired them up too the car and wired the power and ground to the back of the cluster panel on the 2 little screw and thats when it started. I think the power was drawing from the cluster to run the gauges so I'm currently fixing it. Sounds to me like you kinda have a power problem. Maybe it's somethings drawing from you cluster.

[johngriff]

You really only need a single wire for sig from the speed sensor to the signal input on the back of the cluster. Then make sure you have good 12v and ground to the speedo display. If you are getting a bad read, its going to be the wire from the Speed sensor or the cluster, 99% not the speed sensor, it is just a spinning passive magnet w/ metal pickups, kind of too simple for a complex failure.

[Johnsont]

did u ever get this fixed cuz i need mine to work now and it does the same thing goes from 115 backwards to 75

[trustknow1]

I've got same problem with my daughter's 92 hatchback. The speedo started out by operating normally, then would jump up to 85mph plus or minus at 55mph. I changed the speed sensor. No luck. I bought a replacement/salvage cluster (tach was dead). No help. So I started tracing wiring from the sensor to the cluster. The 2 wires from the sensor were yellow/blue stripe and yellow/black stripe. The pair of wires came up from the sensor going through a couple of connectors to a connector mounted to a bracket behind the battery next to the engine fuse block. I had continuity through to this point. I checked continuity from this bracketed connector to the SMJ (Super Multiple Junction) which is located next to the fuse box under the drivers side dash. The front of the SMJ you see with the 10mm bolt is the plug with the wires going into this connector and the wires going out of the back of the conn. go out to different circuits/devices (that's the best way I can explain it). I lost continuity somewhere between the SMJ and 1 of the 2 connectors (the white one) that connects to the 3 plug harness going to the cluster. The SMJ has so many wires connected to the back (out) side of it, that it is nearly impossible to move it to check connections behind it (without causing more bad connections). Somewhere the yellow/black stripe wire changed to a yellow/green stripe wire, so now I'm taking the dash out completely to find where the change happened and, also since I have continuity throughout with the yellow/blue stripe wire and I've lost it through the yellow/black stripe or yellow/green stripe wire I'm going to try to find this wire or wires and tie into it and run it traight to the cluster wiring and see what happens. By the way, the yellow/blue stripe wire goes to the H11 position on the SMJ and the yellow/black stripe wire goes to position I11.....Then again, if you look towards North Missouri in the next few days, you might see the bright light of a car in flames.

[KG300ZXTT]

Well I could make your life easier with the wire colors and connectors if you know how to read the diagram 1. go to this website http://www.240edge.com2. click on manuals3.91-94 240sx4. electrical system (EL)5. Page 43 (You can look at the wire and colors through the connectors)

The speed sensor is like a little generator on the trans the faster it spins the more power if sends to the speedo if there is a voltage spike speedo goes crazy. good lock

[johngriff]

"The speed sensor is like a little generator on the trans the faster it spins the more power if sends to the speedo if there is a voltage spike speedo goes crazy. good lock"

WRONG.

The speed sensor is a magnet with opposing pickups. The opposing picks up make a square wave signal when spun. The increase of rate of the sensor drive increases the pulses per minute, so that Roadspeed = PPM