had my starter and oil pressure switched replaced yesterday. Picked my car and drove off and the service engine soon light came on and the speedometer stayed at zero. Does anyone know what might be the issue? It’s a 87 Trans am gta 5.7

 

I always say, if you have a new problem right after doing some work, it is probably related to that so check the obvious and make sure the connector didn't get unplugged or something of that nature.