The speedo and tach on my wife's 96 GC, 3.8 L mini-van won't activate every time at start-up. They always (so far) activate when starting up the next time. I ran Instrument Cluster test and the Ignition Code Readouts. The Instrument Cluster test was normal. I got two numbers from the ignition code readout. One indicated that the battery had been disconnected within the last 50 key starts and the other had to do with the upstream O2 sensor voltage being shorted to ground.
The battery disconnect code could be related to the problem, so I cleaned the battery terminals and the ground point near the dipstick. It helped a little, in that the failures were further apart.
Now I want to check the speedo/ tach speed sensor and connections but don't know where they are located. Any body know?
Has anyone had this problem and know how to correct it? Paul Paul cut Phil to respond.