My 1998 Honda Civic had 2 diagnostic test last week. One auto machanic found nothing after 1 1/2 hrs accept maybe some wires were bad under the battery. The 2nd test I was told the wires under the car were bad and I would pay for 3 hrs labor, but no new parts were needed. My car speedometer is flying around the dial-its non digital, and my headlights are flicking like someone is shaking the lights.? I just replaced the battery and the alternator checks out fine. What and where are the trouble wires to be replaced or amended?

Well the speedometer since they do wear out when they are non digital and they flick and flick till they break, the lights could be a short somewhere or which I doubt be loose

If it is a mechanical speedometer, likely it is an unrelated problem. I haven't worked on a speedometer since the new tamperproof federal regulations. It used to be a fairly easy job to replace the speedometer cable, non electric, and often solved problems such as yours.

I am not sure why they tend to run wires where they are so hard to get at. Many of the power feeds start near the alternator, which is inconveniently located near the bottom of the engine. Ground wires are just as important. They often are bolted to the engine block near the bottom. If either the power feeds, or the grounds are loose or corroded, they have to be cleaned and tightened. It can be a real pain, even with the car up on a rack. Fixing the wires, should fix the headlights.

I am looking at the printout that the one service center provided me, AND it sayd "will need to repair wires under intake manifold". So 2 things come to mind here, 1- could the mechanic determine that these wires were the problem from the diagnostic test, OR would he have had to put my car on the lift to visually observe them?
2- the young service boy blew it for me, because when he said I woud be charged for labor and not for parts, I asked what does the machanic do to repair the wires? His response was, "I think they put duct tape on them?" he must have seen my expression, because he quickly changed his thought to a bumbling I don't know.
I may not know much about car wires, but no way is anybody going to duct tape my car and charge me $250! So I left. I probbaly should have spoke with a manager. I don't want to get some young kid in trouble, but he's bad for business. He lacked confidence and did not know what he was talking about, he just came off as unsure of himself and nervouse.

So thank you for your replies.

Well if it was black electrical tape then well I use that all the time on quick fixes but that much for a tape up, dumn for sure, but he was probably on to something, the wires could have frayed or have the protective cover melted off and was shorting out to each other but that much for that no way, now for a complete wire job sure.