About 2 days ago, my speedometer quit working. Shortly after the speedo went the check engine light came on.....code 24. I have an 88 Iroc w/ auto trans. Does this sound like a shot VSS?


Thanks in advance

~Red

 

Snapped cable perhaps ??


Code 24 can be set with a functional speedo needle so I would recomend fixing / replacing the Speedo so it shows the correct speed again..... then see if the code is still getting set.

Code 24 also has to do with the ECM, the P/N switch, the TPS and RPM.

 

I would also say its a broken speedometer cable.

The same thing happened to me. The cause was that the speedometer cable somehow got lose where it screws onto the transmission and the end of the speedometer cable got sheared off (making the cable useless).

As for the code 24, I believe that is the speed sensor malfunction which can be set by a broken speedo cable. I also got code 24 when my speedometer cable was broken. The code should only be set when the car is in motion, meaning that when you turn the car on, there should be no check engine light until you drive for a while and then it comes on.

I would recommend that you check your speedo cable at the transmission and be sure that it is still tight and that the tip of the cable is still there. While you are down there, you can also check the speedometer gear that goes into the transmission (its the part the cable screws onto) to be sure that the teeth are not worn out. If that is all ok, check the cable at the back of your gauge cluster (unlikely it would come lose).

The speedometer cable could snap anywhere and you would not be able to tell from the ends. A lot of these cars (82-89) have a two piece speedometer cable. The two pieces hook together behind the power brake booster. Books will tell you to remove the power brake booster to get to the cable, but thats basically impossible (unless you have a rubber wrench that is .1 inches thick or take your entire pedal assembly out). I just unhooked the cable at the transmission and pulled it out from behind the brake booster. Most parts stores only sell the one piece cables but they work just fine. I got an 80'' cable from Auto Zone for $10.

Hope this helps

 

I agree with the guys, check the speedo cable. FYI, my 85 IROC, which has a single-piece speedo cable, would set a code 24 warming up. According to the service manual, a code 24 should be ignored if the wheels aren't turning. The light would turn off after driving a block or so. Strange.

JamesC

 

Don't sound strange to me,........... My 86 Coupe will set code 24 after startup. The C/E stays on till the car moves and the speedo works fine. I bought the car with a dead motor and once the replacement V8 was installed I used a different ECM with an aftermarket Chip for the car ( V8, Carb, EST, 5-Speed, Hypertech).

I figured the replacement ECM, or the aftermarket Chip was setting the 24 code.... It was originally pulled from an 84 Z "HO". ( pulled from the same car as the T5 in my 86) I'll have to look and see if the cable was 1 piece ?!?!