Ignition coil

what are the signs of a bad ignition coil.

Depending upon the type of car the symptom can be a no-start condition (single coil model) or with coil pack or coil on plug models an ignition miss leading to bucking or stumbling.

Many coil failures are caused by aged/misfiring spark plugs, moisture in the plug wells, etc.

In addition to the symptoms listed by OK4450, a bad coil can become sensitive to the heat in the engine compartment and only become erratic when hot, or in the case of a cracked housing can even become sensitive to wet weather.

Nissan Frontiers go way back, at least as far back as the '70s. If yours is old, it may have one single coil that fires all the plugs, if it’s a later model it may be a coil pack or even an individual coil for each sparkplug. What year is your Frontier?

Nissan Frontier came out in 1998, before that they were just called pickup. The 86 to 97 was nicknamed the Hardbody but that was not its official name.

I had a VW Rabbit one time that would stall every time I drove it through a puddle of water. Turned out to be an almost invisible crack in the coil housing.

Keith, you are correct. Apologies for misleading anybody.
Mea Culpa.