Hi All,

I am brand new to posting in this forum. I have been looking for about 3 months and finally found and BOUGHT a 1988 IROC Z. 305 / 5 Spd. Manual. It is displaying a speed sensor (code # 24) error. The car seems to be running fine now. Will it damage the engine or trans, in any way to drive this car back home approx 500 miles. Does the sensor NEED to be replaced at all?

Thanks for the help!


Greg

 

Bump...

 

What exactly is code 24?

 

Code 24 =
Vehicle speed
sensor (VSS) circuit

(All)

• A code 24 should only be set while the vehicle is in motion. Disregard code 24 if set when drive wheels are not
  turning.

• Faulty or loose
  wiring and/or connections at the ECM.
• TPS misadjusted.
  
• Faulty VSS.

 

If your car is fuel injected it will affect fuel milage other then that it will have no effect on your engine or transmission. Is your speedometer working? If it is then the source of you problem is probably a bad wire to the ecm.

 

i thik i may have the same problem, my speedometer isnt working and my odometer stopped,where is the vss located on a 90 rs 5 speed?

 

The VSS tells the ecm how fast the car is traveling to enable/disable certain things(EGR Highway spark, TCC(auto) etc). If I am not mistaken your car uses the optical vss that is on the back of the speedo and outputs a signal to the ecm(yellow box looking thing on the back of the cluster). I would confirm that the wiring is good first then try a new sensor. Try to see if a local JY has a cluster that you can get and swap out the sensor.

 

Easiest way to tell where your vss sensor is by the speedo. If you have a 120 or 140 MPH then it will by in the tail housing of the tranny. If its and 85 MPH it will be on the back of the guage cluster.

 

thanks man

 

 

That is not the case at all from what I know. I have a 120mph speedo and mine on the back of the speedo. This is for a Camaro. Firebird may be different with a digital dash...I am not sure

If you have a cable driven speedo the sensor is on the back of the speedo. If you have an electronic speedo, you have the sensor on the tail stock of the trans (82-88 are optical(back of speedo) and 89-92 are electric(tail stock)).

 

The 2000 PPM optical sensor on the cluster was used on cable driven speedo's. The electronic speedo's used a 4000 PPM vss mounted in the tranny.

I swaped out my cable driven 85 mph speedo for a 89 120 mph speedo. My original had the optical sensor on the back of the speedo, I had to convert to 4000 ppm tranny mounted sensor and buffer.

 

Sorry i didn't catch it was in a camaro...If memory serves I think camaro started using electronic speedo's a year earlier then firebirds. I know in the late 80's GM went from a 2000 ppm to a 4000 ppm speedo.

 

its the round sensor i should say thats at the tail of the tranny? if so how do you go about taking it off and cleaning it up. sorry op for thread jacking

 

The vss in the tranny is functions via the sine wave generated by the magnets, there really isn't anything to clean. Unfortunately it's one of those things that either works or doesn't. Short of checking that the connector pins/wiring are in good shape there isn't much you can do. As far as taking it off there is one small bolt that holds it on, beware it will take a little effort to get the o-ring to unseat if its been in there a while and have a drain pan ready, you will probably have a half a quart of tranny fluid come out.

In my service manual for my 85 I believe there is a section for testing the vss, if I remember correctly it said something about getting the back wheels off the ground and spinning them by hand and looking for a certain output level from the vss using a multimeter. This is probably the only way to truly identify what componet is failing.

 

Yea man after I wrote that I seen where I need to unbolt it and all but again thanks, my speedo and odometer work intermediately, so im going t replace that sensor and hopefully that works I already cleaned up my connection points a couple of times now and after I do that it would work for mile down the road and then stop working.

 

Quick question before I spend a lot on a new sensor, is the top of the gear supposed to move up and down? I know it spins which is common sense

 

I'm not sure what your asking exactly, gear moving up and down?

It should only be spinning.

 

Yes it's moving up and down I can easly take the gear off the of the sensor too, I was told that it's the gear your supposed to change out when you change your gear ratio. Also I noticed that if I take a hard left the speedo would stop working but hard rights don't affect it, so what I'm thinking is that the gear is just loose cause there's no codes being thrown and it's just an intermediate problem. So could I just use some adhesive so it stays put?

 

The gear will fit the end of the vss perfectly. When the gear is on the vss there shouldn't be any movement other then spinning. There should be a D shaped hole in the gear where it fits on the vss, if there is any play in the gear it will need to be replaced. If the gear fits on the shaft well but there is still movement then the bearings have probably gone bad in the vss and it will need to be replaced.

 

ok so my actual gear needs replacing. too easy thanks for all your help MCQUIGG!
anyoe know where i can get just the gear?

 

Anytime.

The only place that I ever found that had the gear I needed was corvette central. There are a few places that have used ones but the more commonly used ones like the 40 tooth are like gold these days.

 

ill figure something out, i need to get the 373 ones, so my speedometer reads the right speed. but again thanks

 

so fixed it today, i didnt need a new sensor just needed a gear, looked onlie and couldnt fid anything, the sensor has to be special ordered at the parts store so what i did was put just the tiniest little dab of super glue on the top of the gear and metal rod to where it doesnt go up and down but still spin. so next time i go to a JY ill just find a couple t5 ad take the gears and take an extra sensor just in case lol. and that was my ghetto fix