RobnLisa

I have an 86 that i'm putting back together after someone abused her for years. I have finished almost everything and now am down to only 2 problems. The first is the ABS which thanks to everyone here I found one of the relays to be bad. The second is the speedometer does not work. I drove it the other night with my scanner hooked up and it reads vehicle speed. With that I know the VSS is functioning properly. The rest of the gauges and tach work properly also. What next?

Robert Perkins

Does the dash self test when powered up? Is the speed display all black with power off? With power on is it just bright with orange tint but nothing displayed?

RobnLisa

Not sure what you mean by self test? With power off its black, with power on it lights up like a christmas tree, all colors just no numbers or bars.

Robert Perkins

Sounds like the display is broken. The dash does a self test when power applied. All graphs go full scale and digital readouts go to 88.

RobnLisa

Nope it does not do that. do I just need to take the speedo out and send that part out? Or do I need to send the whole unit. Is this something I can repair myself?

1984Z51auto

If the speedo is broken and the problem is not just a bad connection at the instrument panel plug in, try these guys for a repair: BATEE.COM. They have a very good rep.

You could also try cleaning the connectors where the panel plugs into the wiring harness with tuner or electrical contact cleaner (carefully... don't get it into the displays).

Cliff Harris

The VSS signal goes to the dash and gets shaped into a square wave and divided by two and then is sent to the ECM. If the ECM reads speed on the scanner then all that is OK.

Your problem is internal to the dash. The microcontroller is what makes the display work. There are also some connectors that are involved. Sending it to Bryan is probably your best option:

http://www.batee.com/corvette/dcrg/s.../iprepair.html

RobnLisa

Thanks for all the help guys! I kinda figured it was the display since I had a reading through the scanner

Robert Perkins

You can also send to www.advancedelectronics.org and they give a discount to forum members if you ask.

RobnLisa

Looked into this issue a little further last night. The Tach side does a self test when you turn the ignition on, but the speedometer side does not.

Robert Perkins

The speedisplay is broken as you discribed earlier. There are three seperate displays in the dash. The speed, fuel/inst and the tach.