Happy Father's Day to you all.

So, I recently bought a 98 XJ SE 4x4 AW4 NP231 8.25 184k cheap. It has an aftermarket remote start with no remote (wonderful) and had a sound system but most of it was removed except the wires and some random tweeters. It has an ignition bypass button in the the cigar lighter socket. The airbags were deployed but not replaced and the wires to the clock spring we're cut, but as far as I know that shouldn't matter in an SE (manual windows and locks.)
The guy I bought it from said it ran fine then 1 day it went into "limp mode" after he topped off the tranny fluid.

I bought a new battery b/c the old one was way
​​​​​smaller and spent. I checked each fuse and
relay. I've cleaned all the grounds except the 2 under the dash (g106 & 107 I think) and the 1 in the rear but all my lights all work. I replaced the ignition switch and actuator and it still won't start by using the key but the bypass still makes it start but it acts like there's no transmission. There is a click sound on the cigar lighter relay when I turn the key from Run to start. The outside of the tumbler where you insert the key makes the chime sounds when you poke it with the key; like the sound it should make when you have the key inserted but have the door open. However it doesn't make the sound like it's supposed to. I imagine that's somehow relevant but I don't know how.
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I refreshed the NSS and got the reverse lights back but no function in the transmission. I even tried a spare NSS that I refreshed from my 97 with no change but I still get P0705. I just have a cheap Bluetooth plug in and the free Torque app. I haven't tested the TSP yet b/c it rained most of the day (my day off). I just wanted to see what the pros think about possible fixes before I rear into the wiring harness & start undoing, patching up spliced wires and yanking out unused speaker wires. Any help would be most appreciated. Thanks.
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1. Fix known problems first. If you know you have wiring problems, fix them and see where you are. Right now, they are clouding the picture.
2. What are the symptoms of "limp mode"? Maybe he used the wrong fluid and just trashed the trans and doesn't know "limp mode" from guacamole.

 

That's what I was afraid of. I didn't want to get deep into the resetting back to stock but it does make sense. The click on the cig relay reminds me of the click my 97 makes when I honk the horn with the fuse pulled. I hope the wiring is more predictable on an SE than a Sport. As far as limp mode, I don't know exactly. Had the XJ towed to my house and my driveway is on a hill so I haven't driven it. Any gear I put it in seems to lunch forward if I rev it up. There's chocks on the front wheels b/c I was messing with the NSS & it's just an extra safety measure.
I tried to drive it once but got to the end of the driveway & had to ****** strap it back so it wasn't in the road.

 

I got the XJ for about the price of a good parts Jeep but after really looking it over, I realized it was in really good shape, clean body & title...hell, the ac even works. I was thinking about stripping it to convert my 97 to 4wd before I realized that this 98 was worth fixing.

 

Looking at the FSM, I​​​​​ know the NSS and Starter motor are fed from the Starter relay and there's a Yel/Red jumper in the PDC that goes to the Junction Box but I haven't got a chance to remove the JB to look for a short or broken wire. Given that the XJ starts with the ignition bypass button, I know I can rule out CPS and CKS. I believe theTCM and TPS also share the same circuit path as well. The transmission fluid is darker than it should be but doesn't smell or look burned.

 

My concern there is that maybe he put in the wrong stuff, which could have you slip-sliding away. It should have Dexron/Mercon III. Nothing else. Chrysler confused the issue a LOT when they decided to start using their own stuff in them, and put out a service bulletin to that effect. But the manufacturer, Asin-Warner, has never agreed and has always recommended plain old Dex/Merc. But, because of the Chrysler disinformation, many auto parts stores will tell you to use something else.

 

I agree but would that knock out the whole circuit? Starter and all? I'm not challenging you at all, I still have much to learn.
My reasoning is that were fluid the issue, wouldn't it throw codes for shift solenoids or TCM or TPS before NSS?

 

I've always use Dex/Merc 3 b/c I cross-referenced Toyota & Mitsubishi's recommendation for their use of AW4.

 

No, no, I was just thinking that the trans not engaging properly could simply be the wrong fluid in it. Nothing electrical.

 

It very well could be part of the problem. The transmission isn't engaging at all.

 

Here's another plot twist... So I pulled the cover shroud off the radio to see how the starter button was wired. The @$$ hat before me cut the cigar lighter connecter out for the cigar lighter to put the starter button in and used the red wire to hot and ran the green jumper to the starter post. That would explain the relay clicking.
Now from my understanding, the ignition switch shares a ground with the cigar lighter at the relay. Could someone please confirm for me? Could this be the source of my problems since the TCU is also on this circuit?

 

If the trans computer has no power, it's going to try starting in 4th gear with the shifter in (D). It'll also give you 1st in (1-2) and 3rd in (3) with no torque converter lockup. Have you checked for power at the TCU? Any codes like P700 for TCU not responding?

 

I've only tried reverse since I'm parked on a hill and don't want to have to drag it back up with my other XJ. Putting it in reverse seems to make it lurch forward but I have to rev it to about 3k rpms. I have not checked for power or continuity at the TCM yet. Only pp705 NSS code and p1694 highahigh voltage to tach we're thrown. I tried draining trans fluid so I could get more Dex/Merc 3 in to flush it out but my XJs nose is facing down hill and I could only get maybe a quart 1/2 out. I was only able to get the lower transmission line off the radiator & didn't get much off of it. When cold, the dipstick read just below the "add" line. I bookmarked CCKen's tutorial on checking the TCU & hopefully have time to do it tomorrow. Thanks for the reply. Do you know if the cigar lighter being cut out would cause the relay to click and keep the starter from completing the circuit? It only clicks in the start position. I'll take pics tomorrow. Ran out of light today.

 

Reverse should give you reverse whether the tcm and solenoids are working. is the throttle body cable intact and adjusted? If that's disconnected it might not develop enough pressure to shift right.

 

I did do the trick on the throttle body cable. I still need to test the TPS too.