2005 RHD Wrangler IAT sensor wiring snapped off and more issues

[00doubleoh]

Hey all, was wondering if I could get some help/advice on this Jeep I just got for my job as a postal worker. It is of course RHD. The thing has been decently kept up. Oil changes every 3-5k and all that. Motor has nearly 300k miles on it, transmission replaced with a jasper reman. Heater core was toast so I went ahead and bypassed it while I wait to work up the courage to tear the dash apart and fix it the right way. The main issues I'm having with it are the following

1. every o2 sensor is throwing a code
2. random/various misfire code
3. rough idle
4. oil pressure dropping to the point of the dash light going off when idle after driving for about 20 minutes

I think all of those are PCM-related but could use some confirmation on that

5. the main reason I'm here right now is that I was planning on cleaning the throttle body, and when I went to remove the air hose connecting it up, the wire connecting the IAT sensor to the manifold snapped, or at least I think it did? Regardless I now have a pigtail just kinda... there. Hanging off the air hose, just chilling.

I've got about a month still before I have to actually use the jeep for my work and want to get it in tip-top shape before then, but I'm having a hard time figuring out where exactly that wire is supposed to connect to. I removed out all the old rotted manifold insulation to see if I could find a wire trace down there but I haven't had any luck so far.

Any help appreciated.

Thanks!

 

[macleanflood]

I'd start with getting an oil pressure gauge...you can rent one from local auto parts stores or buy one on Amazon...and verify you have oil pressure. You'll unscrew the sensor and thread in an 1/8" npt adapter for the gauge.

With 300k I'd be verifying the engine functions before anything else.

Wiring diagrams are in the resources section...8w should be the ticket.

-Mac

 

[Chris]

Hey all, was wondering if I could get some help/advice on this Jeep I just got for my job as a postal worker. It is of course RHD. The thing has been decently kept up. Oil changes every 3-5k and all that. Motor has nearly 300k miles on it, transmission replaced with a jasper reman. Heater core was toast so I went ahead and bypassed it while I wait to work up the courage to tear the dash apart and fix it the right way. The main issues I'm having with it are the following

1. every o2 sensor is throwing a code
2. random/various misfire code
3. rough idle
4. oil pressure dropping to the point of the dash light going off when idle after driving for about 20 minutes

I think all of those are PCM-related but could use some confirmation on that

5. the main reason I'm here right now is that I was planning on cleaning the throttle body, and when I went to remove the air hose connecting it up, the wire connecting the IAT sensor to the manifold snapped, or at least I think it did? Regardless I now have a pigtail just kinda... there. Hanging off the air hose, just chilling.

I've got about a month still before I have to actually use the jeep for my work and want to get it in tip-top shape before then, but I'm having a hard time figuring out where exactly that wire is supposed to connect to. I removed out all the old rotted manifold insulation to see if I could find a wire trace down there but I haven't had any luck so far.

Any help appreciated.

Thanks!

It's not uncommon for multiple O2 sensors to throw codes, especially if they have been exposed to a lot of mileage. The random misfire code could be related to several things, including a vacuum leak, bad spark plugs, or issues with the ignition system. Since the motor has almost 300k miles, it’s worth checking the spark plugs, ignition coils, and also considering the fuel injectors. A good thorough cleaning of the throttle body can help with the rough idle as well. Another thing I would heavily stress is inspecting the wiring harness thoroughly. I can't tell you how many times people have been chasing O2 sensor codes and pull their hair out unable to find a solution. They finally spend the time to go back and check the wiring harness and find short circuits in it with exposed wiring. Unfortunately this can often be a very time consuming project.

The rough idle could be a direct consequence of those misfires. As for the oil pressure dropping, it might be time to check the oil pump or even consider an oil pressure switch replacement if it hasn't been done in a while. Keep in mind that the factory oil pressure gauge is grossly inaccurate. Oil pressure should be tested with an external gauge to find out what your oil pressure really is.

For the IAT sensor, if the wire snapped, you’ll need to find where the pigtail connects. It typically runs to the connector on the intake manifold near the throttle body. If you trace the wiring harness, you may find the other end tucked away. You might consider getting a replacement connector or even soldering the wire back if you’re up for it, just make sure it’s insulated properly to avoid any shorts.

Since you’ve got some time before you need it for work, take a systematic approach to diagnose each issue. It might help to pull a full diagnostic scan to see what other codes come up, which could provide more insight.

Keep us posted!

 

[00doubleoh]

It's not uncommon for multiple O2 sensors to throw codes, especially if they have been exposed to a lot of mileage. The random misfire code could be related to several things, including a vacuum leak, bad spark plugs, or issues with the ignition system. Since the motor has almost 300k miles, it’s worth checking the spark plugs, ignition coils, and also considering the fuel injectors. A good thorough cleaning of the throttle body can help with the rough idle as well. Another thing I would heavily stress is inspecting the wiring harness thoroughly. I can't tell you how many times people have been chasing O2 sensor codes and pull their hair out unable to find a solution. They finally spend the time to go back and check the wiring harness and find short circuits in it with exposed wiring. Unfortunately this can often be a very time consuming project.

The rough idle could be a direct consequence of those misfires. As for the oil pressure dropping, it might be time to check the oil pump or even consider an oil pressure switch replacement if it hasn't been done in a while. Keep in mind that the factory oil pressure gauge is grossly inaccurate. Oil pressure should be tested with an external gauge to find out what your oil pressure really is.

For the IAT sensor, if the wire snapped, you’ll need to find where the pigtail connects. It typically runs to the connector on the intake manifold near the throttle body. If you trace the wiring harness, you may find the other end tucked away. You might consider getting a replacement connector or even soldering the wire back if you’re up for it, just make sure it’s insulated properly to avoid any shorts.

Since you’ve got some time before you need it for work, take a systematic approach to diagnose each issue. It might help to pull a full diagnostic scan to see what other codes come up, which could provide more insight.

Keep us posted!

I've looked over the wiring harness a bit, the some bits of the loom are crusted and falling apart, other parts in great condition. Overall the wiring harness itself still looks good, no exposed, bare wire or anything that I could see from a surface-level inspection. I inspected the connections for it on the o2 sensors as well and those are all great. I planned on doing the spark plugs next week or the week after, but wanted to get the throttle body cleaned up before I do them to make sure the new plugs don't immediately get fouled up which is how I got where I am with the IAT sensor wire.

I was considering doing the oil pump but I heard that the oil pressure switch in TJs can die pretty easily. I'll get an oil pressure gauge and test it at a later date to confirm what the issue is there.

I get the sense the IAT wire is going to be a PITA to get resolved but I'll do what I can and get it soldered up or otherwise fix it some other way.

Appreciate the help! I'll update this as I figure more things out.

 

[Chris]

I've looked over the wiring harness a bit, the some bits of the loom are crusted and falling apart, other parts in great condition. Overall the wiring harness itself still looks good, no exposed, bare wire or anything that I could see from a surface-level inspection. I inspected the connections for it on the o2 sensors as well and those are all great. I planned on doing the spark plugs next week or the week after, but wanted to get the throttle body cleaned up before I do them to make sure the new plugs don't immediately get fouled up which is how I got where I am with the IAT sensor wire.

I was considering doing the oil pump but I heard that the oil pressure switch in TJs can die pretty easily. I'll get an oil pressure gauge and test it at a later date to confirm what the issue is there.

I get the sense the IAT wire is going to be a PITA to get resolved but I'll do what I can and get it soldered up or otherwise fix it some other way.

Appreciate the help! I'll update this as I figure more things out.

You're going to need to do far more than a surface level inspection if it comes down to it, trust me.

Hopefully it doesn't come to that, but if it ends up being one of those issues (which seems more common given the age of these TJs now) where you're pulling your hair out unable to solve it, it likely is a wiring related issue.

Still, don't start there, start with the basic stuff mentioned above and keep us posted!

 

[JKP]

Because it's an 05, it's almost guaranteed you need a new PCM to fix the O2 codes. It may or may not be the cause of the misfires/rough idle. Don't buy a rebuilt one, the only reliable solution is a rehosted one from @Wranglerfix

Check the plugs. The O2s are probably old too.

The IAT wire goes to the PCM, find the other end and splice back together.

The OPDA is known for seizing, yours has probably been replaced by now, but if it says LDI, it's original.

However, excessive wear of the OPDA gear has been known to throw random misfires, so it needs to be pulled and inspected.

The oil pressure gauge sending unit is just a switch that is set at 6 PSI. Less than 6 PSI, gauge reads L. Greater than 6 PSI, PCM moves gauge to mid range. You need to measure the actual oil pressure with a test gauge.

 

[00doubleoh]

To update this thread, I talked to a few different people about some stuff regarding this jeep and came to the conclusion that the best first step was to swap the spark plugs and do an oil change, and most importantly to swap the PCM as I can't trust anything it's doing if I know that thing is fried. So I swapped the PCM and just like magic all the error codes went away except the one regarding the IAT sensor, obviously. Still can't figure out where in the heck that thing goes. Big shoutout to wranglerfix though cause I chucked that thing in there and magically all my problems disappeared. Well, except for the fact that it seems like the AC compressor isn't working at the moment though before I say for sure it isn't I'm going to refill the system with freon, and also I discovered the steering gearbox is actively in the process of dying. So once those get fixed she'll be great I think.

 

[chili_pepper]

Big shoutout to wranglerfix though cause I chucked that thing in there and magically all my problems disappeared.

You can give him a shoutout directly by using @Wranglerfix.

 

[Moglocker]

To update this thread, I talked to a few different people about some stuff regarding this jeep and came to the conclusion that the best first step was to swap the spark plugs and do an oil change, and most importantly to swap the PCM as I can't trust anything it's doing if I know that thing is fried. So I swapped the PCM and just like magic all the error codes went away except the one regarding the IAT sensor, obviously. Still can't figure out where in the heck that thing goes. Big shoutout to wranglerfix though cause I chucked that thing in there and magically all my problems disappeared. Well, except for the fact that it seems like the AC compressor isn't working at the moment though before I say for sure it isn't I'm going to refill the system with freon, and also I discovered the steering gearbox is actively in the process of dying. So once those get fixed she'll be great I think.

How bout the low oil pressure?

 

[00doubleoh]

How bout the low oil pressure?

I talked to my mechanic buddy of mine and he suggested running 10W-40 instead of 10W-30, I haven't had time to properly put her through her paces to test the low oil pressure just yet though after the PCM swap so I'll update later on that one

 

[00doubleoh]

You can give him a shoutout directly by using @Wranglerfix.

Thanks! @Wranglerfix your PCM works great!

 

[Wranglerfix]

Thank you for all of the kind words and support! I am happy to hear your Jeep is back up and running!