[retroflow]

First, the Airbag light went on and would not go back off. It goes on with start, goes off with the rest of the lights, and then comes back on and stays on.
I haven't been able to get it off yet. Right now I'm hopefully letting the thing reset with the Negative cable pulled.

Now, another issue just a day or two later. We were driving along at a steady 55-60MPH, doing maybe 3-3.5k and the Check Engine light will go on for a flash of a second and the engine will hiccup a little. The tach will drop off a little then go back up as it resumes normal. Other times the Tach and Speedo will both drop off, the Check Engine light will go on and the Jeep will really buck and shake like its ready to crap out for a few seconds, sometimes backfiring once or several times before it resumes normal. This may happen a few more times.

It seems to do it when we drive continuously for several miles at a steady speed of around 55-60mph or more - about 30-35k rpm. Almost seems like a thermal issue somewhere. The engine temp is slightly higher than usual, but not by much. At first we thought it was something loose because we were going over bumpy pavement when this started up and there does seem to be a connection somewhere to a rough patch of road and the spazzing. It doesn't only happen over rough pavement, but it certainly happens most often on bumps at freeway speeds. Kinda' weird. I checked around and couldn't find anything loose, but then I'm not 100% sure where else to look besides the obvious - plug wires, dist. cap, manifolds, throttlebody, O2 sensors, injector connections...

It also seems to do it more when both of us are in the Jeep. We're not very heavy people, but the load of 2 over solo may have a role. I go pick her up, no problems. We come back, problems. We drop her at work, problems. I come back, problems. Quick trip at lower town speeds, no problems, either solo nor paired.

I have heard that it could be something as bizzare as the Transmission (it's an Automatic). Either it needs a fluid and filter change or some adjustment, or a sensor is flakey. I have checked the instrument cluster and found no problems. I looked at the Airbag module inside the steering wheel. Looks very clean, nothing damaged. The ECM Diagnostic (on-off-on-off-on) shows nothing but a "12" from when we had the battery disconnected deliberately and the last "55".

I also have heard that symptoms like this can come from a bad sensor: MAP, O2, etc. This is my first modern vehicle with Electronic powertrain and drivetrain controls. I'm starting to lose faith. My '70 Ford Maverick never gave me this much crap. I adjusted the carb as needed, maintained the tranny and mill and did the tune ups. All pretty much mechanical. Ran fine. One cheaply made yet overpriced sensor goes flakey on the Jeep and it brings the whole horse down. Electronics are overrated.

Anyway, does anyone know what this problem may be about? Taking it to a shop is out of the question. I just lost my job and am taking advantage of the downtime to catch up on maintenance and repair on the Jeep. This problem started, ironically, the day I lost my job. Almost like the charm holding the Jeep together was broken. It's been a total pain all week.

Any ideas? And if so, will it cost me an arm & a leg?

[bigman01]

I think it will be next to impossible to find out what it is without a scanner. I may be wrong but cant Auto-Zone pull the codes? I was thinking they will pull them for free if you buy the parts from them.

[retroflow]

Originally Posted by bigman01

I think it will be next to impossible to find out what it is without a scanner. I may be wrong but cant Auto-Zone pull the codes? I was thinking they will pull them for free if you buy the parts from them.

They supposedly can, but I haven't checked yet. I know they and Pep Boys do rentals too. I can check if they have a scanner and will let me borrow/rent or have a tech come outside and try one.

I forgot to mention that at one point last Saturday (it all started on Friday afternoon with the Airbag light) that when we started up again after a couple hours, the fuel gauge looked empty or close to it. We pulled over and restarted the Jeep and the fuel gauge went to the real level, half-a-tank. This was the only time the fuel gauge did this though. All the other gauges were operating normally. The fuel gauge hasn't done this again. Oh, one more thing - the horn and turn signals work fine. If it's the clockspring, it's only throwing the light on. Is it possible that the fault is on the passenger side airbag?

Also: There were two times in the last 30-days or so that I let the fuel level drop into the last 1/4-tank before filling up. At least once, it was on the edge of the red-empty marking. Could this also have some effect?

I have to say that I used Seafoam a couple months back. Some folks swear it's just great and safe, others say it can screw up 02 sensors. Could this also be a factor here? I wanted to replace the O2 sensors when I redid the exhaust system, but at $50 apiece (at a good price), it wasn't feasible. The Jeep currently has 91k and change on it, btw.

I'll keep looking for replies and I'll let you all know how it goes. If it can be fixed or not. Thanks, so far...

[Rule303]

You may want to search this forum for dash gauge problems. Pretty common.

Have you cleaned the battery connections recently? Another common problem. Seems like you are having intermittent problems throughout the electrical system, so thats where I'd start.

Other things affected by a hot engine? Clogged cat. Shorted wires from hot exhaust. Several 2.5 owners on here have reported burned crank position sensor wires, burned by the hot manifold. Check you wires around the exhaust manifold.

[Jerky bump]

It sounds like a poor main ground to me. Did you check all your grounds from battery to engine and body?

[mbyron]

I had a similar problem with the neg terminal on my battery getting loose, but only seemed to make a difference when hot (its a optima yellow top) after several of the "air bag" "Abs" misc goofy lights coming on, I stopped to talk to a neghbor only for my jeep not to start...first thing I checked, battery terminals...the neg came off in my hand...ever since then, after tightening of course, "knocking on wood" I havent had any gremlins...btw, mine is a 97tj 4.0...so I agree with the gentlemen above me here....check those batt connections and def check all the grounds, if you have any mileage on the jeep, might not be a bad idea to clean the grounds and reinstall....depending on what they look like of course....GOOD LUCK

[retroflow]

Originally Posted by mbyron

I had a similar problem with the neg terminal on my battery getting loose, but only seemed to make a difference when hot (its a optima yellow top) after several of the "air bag" "Abs" misc goofy lights coming on, I stopped to talk to a neghbor only for my jeep not to start...first thing I checked, battery terminals...the neg came off in my hand...ever since then, after tightening of course, "knocking on wood" I havent had any gremlins...btw, mine is a 97tj 4.0...so I agree with the gentlemen above me here....check those batt connections and def check all the grounds, if you have any mileage on the jeep, might not be a bad idea to clean the grounds and reinstall....depending on what they look like of course....GOOD LUCK

This was helpful and is a small project on my immediate to-do list. The other night, I noticed I had about a 1/4 can of SeaFoam Deep-Creep and I figured I may as well use the last of it in the Jeep. Even if the valves and injectors weren't dirty from days of "slow" driving around town with this freak weather, at least this may help rule it out. Given the unusually high heat and humidity we've had since July, it could be a valid fault, or at least aggravate one. If anything, there have been numerous times where the tank was less than half full for many days. Significant moisture in the tank at any time like that, is more likely than not. Trying to save money between checks, I didn't get any fuel drier or cleaners. And I was only filling up enough at each time to get me to and from work with maybe one or two short trips for errands. I wasn't filling up, just partials.

Anyway.. While waiting for the SeaFoam to do its thing, I checked the ground and terminals as said above. Nothing seemed out of order. The Negative Terminal seemed tight, but: When I tried to start up, all the electrical power went off, including the dome and underhood lights. I went and jiggled the battery terminal and the underhood and dome lights would go back on but, when I'd try to start, again the power would go off, like a blown fuse or simply like the terminal disconnecting. A couple more times this happened til I went and got the lug wrench and my hammer and I firmly tapped the terminal down. That seemed to do the trick and it hasn't happened again yet. It may be important that we haven't driven out on the freeway yet, so the Jeep hasn't been over 50mph for any length of time. And that the RPMs have barely gone over the 3k mark and only very briefly during acceleration from a stop. Typical lower speed town driving floats between 12k-25k most the time. We haven't been able to duplicate the conditions where things started acting up, I guess until we run on the freeway somewhere.

I'm going to try to inspect the and the battery terminals and cables and clean or replace as needed, weather permitting. I've heard that if the battery gets loose and changes the circuit's voltage, the PCM can get "confused" and possibly throw a code either due to this "disconnection". And it was recommended to me to not just inspect the clamp but the cable for hidden corrosion too. I'll keep you posted.

BTW: The SeaFoam (Deep Creep) smoked like crazy. The first time I tried it some months back, there wasn't much, or any, visible smoke at all and I felt a little cheated. On Friday, it didn't quite fill up the parking lot, but came pretty close. Some members here have said that SeaFoam makes smoke only because it's oil-based and not because it works at cleaning, others say it only seems to smoke when it has dissolved gunk from the engine internals and doesn't smoke much when it's already clean. I didn't use nearly as much this time as I did the first and the difference in the volume of white smoke was enormously obvious. Were the internals gunked and carboned or not? We'll see if it makes any difference. I also filled up the tank and added a pint of regular SeaFoam to hopefully deal with any fuel line issues from this awful humidity.

Thanks to all, so far. Other posts which are similar to mine have been helpful to one degree or another.

Adam

[badoosh27]

i dont know what you have, but if you have a passenger airbag bypass that could be your problem. you can pop it out with a flat head screwdriver and check the wires connecting on the back. mine was sorta loose and the light came on every once in a while, so i jammed it on tight and it fixed it.

[Jerky bump]

--Not sure exactly how your Jeep is setup- but a fusible link can act like that. To check them- one simply pulls on the wire either side of it- if it stretches, you need to fix it. Another outside chance is is a broken battery post.

[retroflow]

Conclusion:

With this problem, it was a combination of things all at once.

The problem with the engine was nothing more than a loose batt-neg cable. This is why the problem seemed connected to rough pavement on the roads at higher speeds. It may have been compounded because the battery tie-down was pretty loose too, which may have allowed the battery to bounce, shift, rock, whatever and aggravate the loose battery clamp. Pretty scary experience though since the symptoms mimicked various problems with O2 sensors, TPS, MAP, you name it. Fortunately, I didn't have money to spend on new parts or I'd really be kicking myself over it. Imagine a couple hundred bucks spent on new parts just because of a loose battery clamp.

The Airbag lamp issue seems to have been pretty classic. It was the clockspring. Because many folks insist that the horn stops working when the clockspring breaks, I wasn't sure why my horn was still working with the airbag lamp lit up. I was worried it was something more serious like the Airbag Control Module or something. Then the horn did stop working and so over time I tested this, checked that and finally got a proper meter and checked the clockspring to find that there was a break in the wires inside. I fixed them - for the time being at least - and all is well.

I hope my writings and those of others here is of some use to you. Good Luck!

[Rule303]

Glad you figured things out. I can't stress enough how important it is for everyone who has electrical problems to pull the battery terminals, inspect them thoroughly, and clean them with a good tool made for that purpose. You have to scrape off the old oxidized material, not just knock off the acid crud. So many on this forum ignore advice to inspect the battery connections and go on to buy and replace numerous expensive parts because they "look" at the battery and it looks ok to them. A sticky on cleaning battery connections might be appropriate since this seems to be a common problem on TJs and so many ignore it until it becomes a problem. I clean mine as a part of routine maintenance about every 30k.