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HO alternator over volting

Joebo — Tue, 12 May 2026 21:46:15 GMT

2015 jku

To make a long story short here I have a js 250 alternator that started over volting right after doing my rad and water pump. (Worked flawless for a while)
Hooked everything back, let it idle to warm up and burp. I got down the road and the bat light came on.

Double checked install, everything fine. It has the big 7 kit. Went through grounds, power cables, 2 pin pigtail, belt and pulleys, etc.

Couldn�t make it right went to put the OEM alt back and it�s perfect. Ended up sending the Js 250 alternator back to company for repair. They say everything looks good. I�m back to square one.

From what I found there�s no battery sensors or IBS. If the OEM alt is fine the PCM should be working correctly right?

What else can I check or try?

Edit: forgot to mention battery voltage is fine at start up then spikes when it heat soaks every time. it usually goes around 15.5. I�ve seen as high at 17+.

Upstream O2 Sensor Voltage Reading

dmburns — Fri, 08 May 2026 14:16:32 GMT

Had CEL for P0420 and P0430 - catalytic converter(s) operating below efficient threshold. Tried CataClean and swapped all four O2 sensors but no luck. Ended up replacing both catalytic converters and reused the same four O2 sensors. The CEL went away for a day but then came back, P0420 and P0430 gone...but now have P2098, bank 2 too lean, and P0038, bank 1 sensor 2 heater control - circuit high. Thinking about trying to look for an exhaust leak, although I've never done that before. Google says to use some soapy water and look for bubbles.. seems easy enough. I did notice that the voltage readings for all four O2 sensors look like they should EXCEPT bank 2 sensor 1 (third one down). From my research, upstream readings should fluctuate between 0.1V-0.9V about once per second and downstream readings should stay relatively stable between 0.5V-0.8V. I tried replacing bank 2 sensor 1 but voltage readings didn't change much. Does anyone have any recommendations on how to go about maybe tracing back a wiring issue that is causing these weird readings? Maybe it isn't even a wiring issue, maybe I should just get another new O2 sensor and swap it out again? Or is this textbook evidence of an exhaust leak on bank 2 side?

Passenger Rear Tail Light Not Working

schwa — Sun, 03 May 2026 17:09:28 GMT

STOCK 2007 JKU Sahara. Rear Passenger Tail Light not working. No exterior light replaced by LED (headlights, tail lights, turn signals etc)

New wiring harness replaced yesterday - OMIX 12403.49 Tail Lamp Wiring for 07-18 Jeep Wrangler JK & replaced with new Sylvania 3157 NON-LED clear bulb. Even swapped left side non-LED bulb to test. Front passenger side turn signal working, no hyperflash, non-led. No trailer package wiring setup.

Rear Passenger Tail Light only works when parking and headlights turned on.
Rear Passenger Tail Light Reverse Lights work
No brake light for Rear Passenger Tail Light
No turn signal for Rear Passenger Tail Light (hyperflash)
No hazard light for Rear Passenger Tail Light

EDIT: No DTC via OBD JScan v15.40 using an OBDLink MX+ -- is there an area within JScan to collect or see data?