First off, is there anyone else out there who feels like everytime you address one problem set you end up getting a new problem? Yeah, I have attained new levels of frustration.
Wife and I decided that the 1 car setup isn't as optimal now the junior is 6 years old. So I just got my 89 IROC-Z back out of the shop from getting the suspension redone, needless to say that was expensive. Car needed A/C work done as well, not that expensive but still, now 2 birds down. Get the car back on Friday and on the way home from the shop the speedometer isn't functioning at all then the SES light illuminates. Once I get in the driveway I pull code 24 "VSS circuit." I put it up for the night and did a few searches on this board and some suggested the ECM, so I have one of those handy and swapped it in hoping for the best. Also based on these threads, I found myself looking in several locations for the buffer box and maybe its the 89 IROC, but I can't seem to find it. Some say its mounted behind the speedo itself, others mounted near the ECM on the passenger side. So now it won't start with either ECM in place and I'm looking at the VSS warning I got. Will a VSS issue keep a car from starting like this? Thanks.

 

The VSS will not affect the starting of the car. Also I'm not a hundred % sure but I've heard that the VSS buffer is only on TBI cars. The VSS code came on because your speedo wasn't working, so when you get it working check the speedo cable.

What is the car doing? Is it cranking or is there just nothing when you turn the key?

 

The VSS is on 89 cars, the exact location I can't seem to find a definitive answer. I picked the car up from the shop who did the A/C work. They put in a new blower box and hooked up my heat only. The speedo has always read off since I swapped in a new rear going from the 9-bolt 2.77 -> 3.27 rear. It then developed a creeking/whizzing sound for awhile and when I picked it up from the shop the speedo not working was the first thing I noticed. I filled it up with 2.5 gallons of fresh premium 91 fuel since it has been sitting quite long in my garage (being fired up and run once a month.) at the shop when I went to pick it up and it banged right up no problem and drove home. I drove it around the block a few times after the code 24 set just to test out my new suspension and now I go out today and it won't start. It cranks and cranks(TJ Jr. hi-torque ministarter), fuel pump whirls each key-on cycle(walbro 255 pump). I simply can't figure out why this no-start would ensue right after the code set.

 

I can assure you that the VSS code has nothing to do with the no-start situation. It sounds to me like you'll have to do some trouble shooting starting with basics, testing for spark and fuel.