No Electrical Power on 1997 Jeep TJ Wrangler

[MONTY]

 Hello Mose, the battery on my TJ has been weak. Cold weather,  I had to charge the battery. I tried to start , it turned but wouldn't fire. Next morning it was completely dead. Installed in new battery and now I have no power at all, no lights, nothing. I checked the fuses in the distribution panel. All were good. Need some help on this one. 

Thank you, Roger

[Moses Ludel]

Hi, Roger...So, I would begin with a simple check of the battery voltage.  Read this at the starter motor end of the positive battery cable with the +/positive voltmeter probe.  Hold the voltmeter -/negative probe to a chassis ground or the engine block.  You should see 12.6V or higher volts.  If not, the new battery is either not charged or has a defective cell, post defect, etc.

If the battery has voltage at the starter motor, you still need adequate contact between the battery cables and the battery terminals.  Clean the battery terminals by removing the negative terminal then the positive terminal.  After cleaning the terminals, install the positive cable first, then the negative cable.  That should assure that the available battery voltage has minimal resistance at the cable terminals. 

If the positive or negative battery cables are suspect, use your Ohmmeter to check ohms resistance between the positive battery terminal and the starter end of the cable and also between the negative battery terminal and the other end of the negative ground cable.

Try the parking lights before attempting to crank the engine.  The parking lights work independently of the ignition switch.  If these lights work, turn on the headlights and try cranking the engine.  Have someone watch the headlights while cranking to seen how much they dim or go out during cranking.

If the lights dim considerably or go out, you likely have a defective battery.  You can also determine this by taking the battery to the store and having them load test it.  I recently bought an inexpensive Harbor Freight 100A load tester that can perform a load test although the load is only 100A.  (Starter motor load is considerably higher than this.)  The device costs $20.  $50 and up will buy a higher amperage battery load tester.

Your other possibility would be the fusible link in the battery cable.  If that somehow "tripped" (burned through), you would not have current flow to the circuit, only power to the starter motor.  You could see whether this has occurred by safely (vehicle in Park or Neutral, wheels chocked, E-brake set, etc.) jumping the terminals at the starter to crank the engine.  If the engine cranks, the fusible link is likely at fault, and there is no current to the rest of the system.

Moses