I am getting a check engine code 24 on my 87 Irocz 305 Tpi 5 speed. Can any one help me. Trying to determine whether I need a new vss or a new vss buffer. Also can some one tell me the location of both in my 87 Irocz. Also if anyone can provide a troubleshoot tree for code 24 for my 87 it would be greatly appreciated.

 

On an '87 IROC the VSS & buffer are one unit. It is located behind the speedometer cluster. There is an optical pickup mounted via a single screw, then a small box with a three wire lead to the optical piece.

RBob.

 

Im not sure how to test the output to the ecm, but since the ecm has been just replaced Im kinda ruling that out and the trouble tree on chevythunder.com points towards a bad memcal But Im not thinking thats too too likely. Maybe rbob can say how to the the output too the ecm pin a10 .

The piece rbob is talking about is acdelco acdelco 213-108, gm 25007318 , standard motor product sc26 for the optical cable driven.

http://www.ebay.com/itm/SC26-BUICK-C...ht_4217wt_1055

 

Long ago my 85 used to show a check engine light, code 24, when the car idled for a few minutes, then go off after I'd driven a block or so. The shop manual says to disregard the code if the wheels aren't turning.

JamesC

 

that doesnt seem right just ignore the light sounds like a engineering issue of 85. his light it popping on when the car is not moving as well.

 

It can happen due to the way the malfunction test for the VSS works. It is tricky to figure out if the vehicle could be moving or not. The test basically uses LV8 or MAP along with RPM to decide whether the vehicle is in motion.

If the ECM thinks that the vehicle is moving, whether it is or not, and no VSS signal it sets the code for it.

A high idle due to other reasons will trip the VSS code.

RBob.

 

Thank you guys for the replies I am still currently dealing with this issue have been busy but I am determined to get rid of my engine light. When I go to the flow chart on Chevythuder.com

http://www.chevythunder.com/vss_code_24_sd_199092.htm

At the very top it says applicable to 90-92 Tpi. So my question is can I use this flow chart when dealing with my 87 Tpi?? Or should I disreguard the flow chart given in the link above and just replace the part that Rbob mentioned?

Thank you guys. Appreciate the info.

 

I wouldn't use that flow chart for a 87 the vss buffer is external from the ecm. If this is cable drive it is more than likely the part rbob mentioned. If you have a magnetic vss then you will have a vss buffer and should start with testing to see if you are getting a vss signal to the buffer and buffer power and ground.

 

 

And how can I tell whether I have cable driven vss?

 

look at your transmission tail housing on the drivers side see if you see a cable coming off the transmission or a vss.

 

 

 

That's not it is it? Tried to stick my head under but my head is too big lol. its further bach huh?

 

you picture didn't post. You can pull your cluster as well to see if its a cable or vss on the trans.

 

An '87 Camaro will have the optical pickup in the cluster, as I posted in my first post of this thread. All of the more recent posts do not apply to this VSS.

RBob.

 

Are the part numbers given above correct for my car? acdelco acdelco 213-108, gm 25007318 , standard motor product sc26

When I check the compatability feature on ebay says it is not compatable:

http://www.ebay.com/itm/Acdelco-213-...-/230618927405

I also checked other ebay auctions using the same compatability feature and says it is not compatable...

I did find this on autozone website:

http://www.autozone.com/autozone/par...fier=59292_0_0_

and when I type the part numbers you guys gave me into my autozone app on my phone that same part in the link above comes up. I'd rather buy AC Delco I think... are they the same?

Also in the specs under notes on the autozone site it says "digital dash" what is that referring to? I have the stock speedo with the needle it is not digital...

 

And I take it sense the VSS and buffer are the same unit replacing this unit should definitely get rid of my check engine light code 24 right?

 

I think they must have the application years wrong, as far as fixing your code 24 it can be caused bye high idle when the car isnt moving it will set the malf.

As far as if it will fix your code 24 im not sure.

Code 24- A vehicle speed sensor malfunction will set this code. The conditions for it being set is vehicle speed at 0 mph, engine speed between 1500-3000 rpm, tps less than 2% open, and the transmission not in park or neutral. These conditions must be met for about 10 seconds. A faulty VSS will affect the operation of the TCC, IAC and ignition timing.

http://www.ebay.com/itm/NEW-NOS-GM-A...226d72&vxp=mtr

 

Nice that's a good price too!