I would like to know how I can find the wire where I can test my cars manually for and codes. Likely I got this car and the speedometer doesn't work, I had replaced the vss speed senor but it still doesn't work. So I bought a new guage cluster on the way. But somehow while driving the speedometer who work and at times it won't work at all. All the other guages like gas and oil seems to work fine except the speedometer. But what is also wierd is that the check engine light comes on. I was wondering how I can check it witout the diagnositic tool. If someone can help me I very much appreciate it.