Survivor87
06-22-2005, 09:56 AM
My '87 GN turned on the SES light the other day when the wife was driving it. It had put up code 24 (VSS), and then when I drove it I noticed the speedo wasn't working. Determined it was a broken cable. I have a couple of questions, though. This is a two-piece cable with a reducer just in front of the firewall. I was told this was part of an overlay package from an unknown vendor (145 MPH speedo face). My Buick parts guy ordered me a cable, saying he thought it was a two-piece unit. It is P/N 88959481. Of course it came in as a single piece and he says it shows to be correct for the car. Was there a cable set-up from some other application that is supposed to work with this overlay, or do I have the wrong part from GM? The short cable from the firewall to the dash is the one that is broken.
The second question is: What does the ECM do with the data from the VSS? The reason I ask is because I have observed the vehicle speed reading on a scanmaster to be off (slow) as much as 7-10 MPH versus actual speed. I'm sure this is because of the reducer slowing down the cable so the overlay will read right. Wondering if this could have an adverse affect on performance or driveability. Appreciate any advice on either of these questions.
Steve Allen
The second question is: What does the ECM do with the data from the VSS? The reason I ask is because I have observed the vehicle speed reading on a scanmaster to be off (slow) as much as 7-10 MPH versus actual speed. I'm sure this is because of the reducer slowing down the cable so the overlay will read right. Wondering if this could have an adverse affect on performance or driveability. Appreciate any advice on either of these questions.
Steve Allen