Hey everyone, I mistakenly hooked up my 1997 Jeep Cherokee XJ battery backwards and caused quite a few issues. I immediately noticed smoke from the front of the PDC fuse box where the power and alternator wires live. I’ve ran a bunch of tests, but I’m no longer sure if I’m making progress. This is my first attempt working with electric and multimeters and any help regarding next steps would be greatly appreciated.

The car runs perfectly fine now including all lights, but the following items are not working:

• Power mirrors (No power locks/windows)
• Rear wiper
• Climate Control/Blower
• Electric Fan
• Speakers

Items replaced:

• - Ignition switch (no impact)
• - Alternator – Car on would show lower battery volts than car off (Check Gauge light went away after replacing this)
• - Cable from alternator to PDC (where I saw smoke)
• - Fuse on aftermarket radio (radio worked after this)

Items checked:
- PDC

• All fuses check okay
  • Fuse 16 (Power Amp) blew and replaced, did not blow again. This got the car started again
• Battery to PDC checks 12.6V (car on), ~13.3v started
• Relays have been rearranged and had no impact
• PDC was removed and no signs of burned/melted wires

- Fuse Panel (wires look okay)

• All fuses get connectivity. The following fuses I get fluctuating voltage:
  • 3 – Left headlight high beam
  • 4 – Left headlight low beaM
  • 5 – Right headlight low beam
  • 6 – Instrument panel dimmer
  • 7 – Left parking light
  • 23 – Right parking light
• Fuse 19 - Starter Relay
  • gets a reading of 129.2 (car on), 81.2 (car started)
• Fuse 25 – ABS (car doesn’t have it), Climate Controls, Cooling Fan, Brake Switch
  • Fuse 25 was bad, I replaced it, the blower turned on for half a second and the fuse blew again.
  • Unplugged the electric fan, turned on the car, fuse 25 blew again
  • Unplugged the blower resistor, blower, climate control, and rear wiper
  • Fuse 25 did not blow.
  • I proceeded to plug each accessory in 1 by 1. The fuse never blew, but the accessories won’t turn on. The fuse now test correctly at 12.6V.

- Ignition Switch:

• Only the blue wire is showing 12.6v with car on. Couldn’t reach the other wires with a multimeter while running.
• Ignition switch wire unplugged (car battery unplugged, (wire to ground (is this the correct way to test these?) I am not getting continuity with:
  • Yellow
  • Black with orange stripE
  • Black with white stripe
• I get continuity with (wire to ground)
  • pink and red stripe,
  • black small,
  • red grey (black stripe)
  • blue

- Blower Motor:

• Unplugged blower motor, went from ground to one of the prongs of the plug and got fluctuating voltage

- Blower motor resistor

• Showed connectivity on all terminals
• Blower motor resistor plug test (unplugged from resistor
• 2 of the 4 resistor plugs had connectivity to the climate control panel (Blue and Orange Stripe)
• Blue and Orange had a fluctuating voltage reading
• Green and orange/brown did not have connectivity to the climate control panel
• Green and orange/brown read 12.2V