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URGENT: MIL light 5 hours from home

NewToJeeps

NAXJA Forum User
2000 XJ, 206k Miles
Automatic aw4 transmission
4.0

All:

I'm writing this from my phone in my motel room in Nags Head, NC this am... Came down with my old lady for some R/R and some surf fishing. About an hour out from Manteo, MIL light comes on while cruising at about 65mph. No noticeable changes in driveability at all. Luckily, a few miles later I was able to pull into an auto parts store and had them pull 2 codes: PO700 & PO740. Was able to make it to our motel with no driveability issues whatsoever. I'm about to find out if this morning if it's still OK.

We're planning on taking it on the beach to fish, and I'm concerned about having something happen while up on the sand in 4x4... We're also 5 hours from home!
I've always kept up with regular maintenance and consider myself moderately mechanically inclined. Not afraid to get hands dirty ;)

Recent work includes:

-rear diff serviced
-new plugs, gapped to spec
-serviced​ air filter(cleaned and oiled k&n) in stock housing
-oil changed
-valve cover gasket replaced
-transmission pan dropped and gasket/filter changed
-ball joints and front axle u joints replaced.

That's all the recent stuff I can think of for now. Never had MIL come on before. Since I'm on my phone, both my data and search ability are limited outside my motel's WiFi range. My initial search results on these codes were fruitless.

Hoping it's something I can wait to address until after I get back home, but any help would surely be appreciated.

Plan on driving it to breakfast and seeing how it acts up (if at all) this am when cold. I'll report back in couple hours..

TIA everyone!



Sent from my Moto G (5) Plus using Tapatalk
 
Yep, trans issue. I really wouldn't worry about it. Trans temp will run higher if it's not locking up, no other side effects probably.

Since you just serviced it, double check the trans fluid level.

Enjoy your trip and deal with it when you get home.
 
Was the correct fluid used for the transmission ?

Other thing mentioned with those codes is pulling a plug(seen from under the jeep at the transmission), cleaning it then reinstalling. Not sure what it looks like or where it is, but ought to be obvious for the other post about it.
One person said it their TPS that fixed it. Others had a bad torque converter.


Sent from my iPhone using Tapatalk
 
Had this same exact issue in my 05 Liberty. Won't strand you or anything for now. When it starts going into limp mode you'll know.

The PO700 just means it's a tranny issue not an engine issue. PO740 means torque converter lockup isn't happening when it should. If it's in the early stages, it'll probably only happen on longer trips (2 hours or more), as that's when there's enough heat to create slippage. Around town and on shorter trips it probably won't slip. Although mine did slip and go into limp mode with a trailer hooked up. Off road it was ok. I threw parts at mine to eliminate all the simple stuff before taking it in and it ended up needing a trans overhaul. I'm not sure how much tougher the AW4 is compared to the 42RLE of the Liberty, but by the time you get that code, the TC clutch material is already swimming around in your trans.

I know a few people that drive around like that for years, so don't worry about it stranding you on your vacation. I just couldn't stand the MIL and knowing my trans was dying, albeit slowly so I got it rebuilt. Maybe the AW4 won't require a full rebuild.
 
Had this same exact issue in my 05 Liberty. Won't strand you or anything for now. When it starts going into limp mode you'll know.

The PO700 just means it's a tranny issue not an engine issue. PO740 means torque converter lockup isn't happening when it should. If it's in the early stages, it'll probably only happen on longer trips (2 hours or more), as that's when there's enough heat to create slippage. Around town and on shorter trips it probably won't slip. Although mine did slip and go into limp mode with a trailer hooked up. Off road it was ok. I threw parts at mine to eliminate all the simple stuff before taking it in and it ended up needing a trans overhaul. I'm not sure how much tougher the AW4 is compared to the 42RLE of the Liberty, but by the time you get that code, the TC clutch material is already swimming around in your trans.

I know a few people that drive around like that for years, so don't worry about it stranding you on your vacation. I just couldn't stand the MIL and knowing my trans was dying, albeit slowly so I got it rebuilt. Maybe the AW4 won't require a full rebuild.

More often than not, the P740 is a bad solenoid. That's a relatively easy fix that can be done by dropping the pan.
 
Hey everyone,

Just got back home my trip to the Outer Banks.. sorry for not checking in earlier but the connection at the motel was extremely spotty.

I see I have some replies with good information, so first things first: thank you all.

I did some very limited reading up on the codes the first night and came across some info where someone had recommended checking the plugs near the transmission dipstick tube. I figured this was simple enough, so before I left for breakfast, I unplugged one of them, inspected, and plugged back in. I'm not sure what it was or even what color it was. I tried to do the same to the other two nearby, but they wouldn't come loose so easy, so I left it alone... During this unplugging, it suddenly dawned on me that I de-greased and cleaned up the oil film on and around my engine a couple months back before doing the transmission pan and valve cover gasket...yes, there was some water splashing around in the engine bay... hmmm....

Anyway, something strange happened: I got in the jeep to go eat about 2 miles down the road. The light came on as expected, and I drove fine to the restaurant. No noticeable difference in driving. Power was there, shifting was on point, etc. Parked, shut off the engine and went to eat. About an hour later, I came back and turned the jeep on, and noticed the light had disappeared! I didn't get my hopes up too much and decided to drive a bit more, at least to get to operating temperature. No light - it stayed off.

Decided to not think about it too much and continue with my vacation. I did my fishing and even took it onto the beach sand in 4-Low. No problems whatsoever. I put some good miles up and down the islands with some off-roading in between and all went well. When the time came to come back home, everything went smoothly. My gas economy was excellent and no problems shifting up or down - all good even while running the A/C.

Now, I'm not sure, but I think the codes are still stored in the system, right? I'm thinking that the water might have gotten into the harnesses from the wash, and when I unplugged and plugged back in, some connection might have been re-established, maybe?

Maybe this is all just wishful thinking, but hopefully someone who knows better can chime in and shed some light on this and where I should go from here... I'd obviously like to tackle the little stuff before it develops into potentially something bigger.

D
 
Hey everyone,

Just got back home my trip to the Outer Banks.. sorry for not checking in earlier but the connection at the motel was extremely spotty.

I see I have some replies with good information, so first things first: thank you all.

I did some very limited reading up on the codes the first night and came across some info where someone had recommended checking the plugs near the transmission dipstick tube. I figured this was simple enough, so before I left for breakfast, I unplugged one of them, inspected, and plugged back in. I'm not sure what it was or even what color it was. I tried to do the same to the other two nearby, but they wouldn't come loose so easy, so I left it alone... During this unplugging, it suddenly dawned on me that I de-greased and cleaned up the oil film on and around my engine a couple months back before doing the transmission pan and valve cover gasket...yes, there was some water splashing around in the engine bay... hmmm....

Anyway, something strange happened: I got in the jeep to go eat about 2 miles down the road. The light came on as expected, and I drove fine to the restaurant. No noticeable difference in driving. Power was there, shifting was on point, etc. Parked, shut off the engine and went to eat. About an hour later, I came back and turned the jeep on, and noticed the light had disappeared! I didn't get my hopes up too much and decided to drive a bit more, at least to get to operating temperature. No light - it stayed off.

Decided to not think about it too much and continue with my vacation. I did my fishing and even took it onto the beach sand in 4-Low. No problems whatsoever. I put some good miles up and down the islands with some off-roading in between and all went well. When the time came to come back home, everything went smoothly. My gas economy was excellent and no problems shifting up or down - all good even while running the A/C.

Now, I'm not sure, but I think the codes are still stored in the system, right? I'm thinking that the water might have gotten into the harnesses from the wash, and when I unplugged and plugged back in, some connection might have been re-established, maybe?

Maybe this is all just wishful thinking, but hopefully someone who knows better can chime in and shed some light on this and where I should go from here... I'd obviously like to tackle the little stuff before it develops into potentially something bigger.

D

If it's not coming back, then you're fine. I believe old stored codes get cleared out after 50 on/off cycles.
 
Mine would come and go, sometimes months at a time without seeing it. I'd swap the solenoid pack out if you get a chance. If the fluid looks clean in the pan, it's probably just an electronic issue. I don't wanna be a downer but I don't want you to get bummed when it comes back (if it does!)
 
Mine did this before the solenoid finally failed. Plan on getting it changed soon.
 
the only other thing i can think of and im not sure if it would even trigger the code is if some air worked its way into the solenoids and when the tc lockup was called it took longer than normal to engage and triggered the light.

but again this is just a speculation.
 
The solenoid is singing its swan song. The good news is when it totally fails, it wont leave you stranded. You most likely wont even notice the drop in fuel economy.
 
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