armstrongi

Hello Jeepsters,

Just wanted to post my current issues and see if any might have any tips or experience with the following issues that I'm experiencing, also wanted to contribute an issue that I resolved recently in the hopes that it might help someone else.

Issue 1: AC Blower not functioning, turn signals went out at about the same time. (Hazards worked fine) Fuse #20 under the dash would blow repeatedly.
- Of course I ordered multiple parts (Blower motor with fan, Blower regulator, Multipurpose signal relay) none of which resolved the issue.
- Found a couple of posts that mentioned the Neutral Safety Switch wiring being a possibility. I knew this to be problematic on my Jeep as I'd recently replaced my NSS and saw some bare wiring down by the transmission leading to the NSS (Plug type).
Solution: Separated the bare wires.leading to the NSS and taped them individually. insterted new fuse #20. Blower now working, turn signals working. Magic.

Issue 2: P0031 - O2 Sensor Heater Control Circuit → Low Bank1 Sensor1
- Replaced the front, upper O2 sensor twice. No joy.
- Points to wiring issue in one of the 4 wires in the harness I suppose. (or PCM/ECM issue) I have a test light and a multimeter but I'm a bit of noob (but learning) when it comes to using them. Could really use a wiring digram specifically for my model year as the 2001 digrams I've found use different wire colors.
- I can trace the 4 wires to a massive bundle of wrapped wires that run past the head cover and around back of the engine. I suppose I could cut the jacket off and trace the wires but seems like there should be a better way to diagnose it than to brute force it by unbundling the wires and physically tracing and checking them.
- If someone could post a O2 and ECM pin-out wiring diagram for the 2003 JGC Laredo 2WD 4.0 that would be awesome, additionally a quick primer on how to pinpoint which of the 4 wires might be faulty would also help.

Issue 3: This might actually be two issues. Starting in Park and failure to engage in Drive and Reverse.
3A: After starting the vehicle, placing the stick in Reverse or Drive, the transmission doesn't always engage. All that's needed typically is to drop it to Neutral and then back to R or D and then it engages fine.
- A couple years ago I had to drop my transmission (first time doing this, thanks youtube and bleepinjeep!) in order to get to rusted freeze plugs, this issue began after that. The transmission works fine otherwise, shifts appropriately, etc. This issue is more of an annoyance since it always gets engaged eventually but it'd be nice not to have to deal with it.

3B: When starting the car, once out of every 4-5 starts, the ignition won't start in Park, shifting to neutral and starting nearly always fires it up without further fiddling.
- replaced the NSS a couple months back, this seemed to begin the cascade of other issues above but not sure they're related. (The O2 sensor issue cropped up right after then NSS swap) Reverse lights are functioning fine.

Sorry for the long post but wanted to include as much data as possible to reduce followup questions but please feel free to ask whatever is needed. Please provide tips or insight based on your experiences with any of these issues if you can. I would appreciate it greatly.

All the best

Caish

Shifting,
Sounds like cable adjustment.
Would explain not starting too, I would also check the switch on the shifter in the console.

armstrongi

Caish, thanks for answering. After researching shift linkage adjustment, it does appear that this might actually fix both of these issues (3a/b) as you've mentioned. I'll dig in more and try adjusting things this weekend and let you know the results.

btw - I researched using a multimeter and tried checking voltage from the O2 sensor back to the PCM, while I didn't get any voltage reading (Due to the ASD relay cutting off the circuit and not being bypassed), the O2 1/1 code P0031 has gone away. Seems that I might have slightly adjusted the pins in the connector a bit and now are making better contact? Not sure, just know the code has cleared for several days. Thanks again for your help.