Truck will not start. on 2004 Chevrolet Avalanche 1500

i have troubleshot the starter, battery and ignition circuit, when i turn the key i get full power to all accessories, radio works and dash voltage meter reads 12vdc, sometimes when i wiggle the three wires (yellow, black and purple) it turns over, i have tried using a dielectric grease on that connection and it worked for about a week then started again.

1 answer
test the battery at the battery I wouldn't trust dash readings if it test good test the starter if the starter just clicks its probly bad