Hi fellow Thirdgen members. I got a question. Before I start tearing apart my dashboard, I wanted to ask if anyone knows if my 1986 IROC-Z (VIN CODE "F") 305 TPI has a VSS because while in motion, the Check Engine Light turned on. I dont have the speedo cable hooked up but soon, I will replace it. Thanks guys.

 

without the speedo cable, it will set a code for the speed sensor.
the speed sensor is on the back of the speedometer.

 

So my cluster does support a VSS. Thanks bro.

 

Hey guys. My car sets a code 24 as well. I had a question for you all.

The code 24 always seems to happen only when coming to a stop or sometimes when leaving from a stop. My speedo cable needs to cleaned and the needle bounces bad around this speed. Could this be throwing the VSS buffer on the back of the speedo off and causing a code 24?

 

Sorry. I have no clue. Hopefully someone else can help you out.

 

Okay. i finally installed a new speedo cable and now the SES light dont come on, but today I went to have the tachometer tested and BANG! There was the troublecode 24. So the Guy deleted it through the computer that connects into the ADLD port and it came right back (trouble code 24). So now that I know that the VSS is bad, where can I get it replaced or fixed? Forgot to mention, ever though I get this trouble code, the SES light wont come on. It use too prior to installing the speedo cable .

 

you should beable to buy a replacment for that

 

Im going to look around. Peace.

 

i don't think you can clear the codes thru the ALDL on a 86, but i could be wrong.
code 24 will also set in park or neutral if the ECM thinks the car is in gear and
engine RPM is too high for a certain amount of time.
IIRC, 1500 RPM or higher for more than 15 seconds.
so with a scanner check the P/N switch to be sure its working and adjusted right.

 

OK. sounds good. while in nuetral, I knew that my tach was failing because it read over 3000 rpms. So when I took the IROC to get checked for a bad injector, the guy pugged in a scanner and gave me that code. While connected, he turned on the IROC and I glimpsed at the screen and saw that the rpm's where in fact 1000 rpm's. When I was driving the SES light would turn on. But now that I put in the speedo cable, it never came on. So Im going to disconnect the battery before I go to work to clear the code, then Ill do a quick grounding of terminal A & B to see if the code comes back. Ill let you know what happens. Thanks.

 

My shop manual says to ignore code 24 if the wheels aren't turning. My IROC used to show the check engine light (code 24) if I allowed it idle very long, but the light would shut off after I'd driven a block of so.

JamesC

 

NO MORE TROUBLECODE 24. All I did was disconnect the battery, install a new speedo cable, re-adjusted my TPS, re-connected the battery and then I took her out for a test drive. I then parked, ran the trouble codes and received a code 12. As an added bonus, my IROC doesn't stall anymore.