I have a 96 k1500 4X4 ext cab that has a ground wire problem. As of now the radio and cruse control do not work and the tach and speedo read high then bounce around when I apply the brakes or use the turn signals. It does have one code P0719 which I cleared but made no difference. The truck starts, drives and shifts fine. This is what I have doe so far. Cleaned and checked the following ground wires: 2 wires on the passengers side of the front lower part of the engine block. 2 wires on the passengers side of the rear of the cylinder head. 2 wires on the thermostat bolt Passenger side chassis ground in the engine compartment where it bonds the chassis to the body. The body ground from the battery to the body. Ground wires on the left rear frame near the spare tire. Ground wire behind the driver’s side headlight. The ground wires under the dash near the scanner port. Are there any other ground locations I missed? Is there one for the HVAC? I also removed and cleaned the speed sensor and replaced the ignition switch and the battery. Then I removed the dash and checked continuity of the ground wire from under the dash near the scanner port to each plug in the dash ( radio, instrument cluster, ext.) and tested fine on my fluke meter. I then replace the instrument cluster with one out of a 98 k1500 and it made no difference. I also ran a 14 gauge auxiliary ground wire from the battery to body to the frame to the ground lug under the dash by the scanner port. Still no luck. Any help would be appreciated.