Jeep Wrangler Forum banner
  • Hey everyone! Enter your ride HERE to be a part of JUNE's Ride of the Month Challenge!

1 - 10 of 10 Posts

·
Registered
Joined
·
10 Posts
Discussion Starter · #1 ·
Hello,

New to forum here, as well as to Wrangler ownership. Took delivery of my '01 TJ a week ago this past Monday, so just a few days shy of 2 weeks of ownership. Have been trying to work out a few bugs, one of which has been the 'Check Engine Light' illumination. I purchased the 'Harry-Homeowner' version of a scan tool, and read the code and determined my bank 1 sensor 2 O2 sensor was bad. Purchased a new one from local Auto Zone only to find that the Bosch Sensor was considered by many to be 'taboo'. So, returned it and ordered a genuine MOPAR part. Also, had a local Jeep Tech use the Dealership's DRBII to read and confirm the codes. Seems that while the front bank (1) down stream (sensor II) O2 sensor was confirmed as bad, there was also a problem with the heaters. The tech found the fuse blown, so we replaced that, re-set the light, and on my way I went with the old O2 sensor still in place. Light stayed off all the way home (about 20 miles), but light came back on upon the first re-start and fuse blew again. So, new O2 sensor arrived this past Tuesday, and I installed it Tuesday pm, replaced the fuse, and removed the codes with the Harry-Homeowner (HH) scan tool. Things looked good from Tuesday pm through last night, however, upon my first start of the day today, the light came on again, and the fuse was also blown. I installed a new fuse, reset the system, and light came on within about 2 seconds of my next re-start.

So...that's where I'm at! Anyone got any ideas about this? The Scan Tool still reads 'Bank 1, Sensor 2' as being the problem. I might add that when the Jeep tech read the codes last week he indicated something strange. Seems he was able to control voltages on 2 of the remaining 3 sensors....but was getting no reading from the 4th. He could neither control the voltages, nor did he indicate any type of 'heater' problem in that circuit even with the fuse blown. Considering all 4 of the O2 sensors are most likely powered off the one 15 amp circuit....seems we should have seen a code for the heater on that remaining sensor as well. But, we didn't. So....that pretty much concludes the story as it sits at the moment. If anyone has any ideas about this, please let me know. I'm curious if this could be 'controller' related? Might this circuit run through the ECM in such a way that a problem within the Engine Controller could be causing this whole issue?

Any help is greatly appreciated!! Many thanks, Tom D.
 

·
Registered
Joined
·
451 Posts
It is common for the harness to rub through and short the wires which blows the fuse. Follow the wire harness from the O2 sensors to the PCM and look for any areas where the harness is rubbing metal, pay close attention to the area where the harness goes behind the head near the fire wall, the studs at the rear of the valve cover.
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #4 ·
Digger, X2? Not sure what you mean by that.

Digger and CDC....thanks for the advice. I'm thinking that's the problem.....a chaffed harness.

Guess I'll have to go crawling around under there. Damn! I hate looking for wiring issues like this!

WC
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #5 ·
OK, this is a follow-up with what I hope will be a report on the 'final fix' to the problem. After taking it to my local dealership, the report came back as predicted above: a chaffing problem caused by what appears to be a sharp edge of a protruding head gasket which cuts through the harness and causes the heater fuse to blow. What's interesting about this is that there seems to be no correlation between the P106 code, which is for a 'bank 1 / sensor 2' failure.....and the fact that the problem is actually a grounding heater wire. Further, there were 2 other codes also tripped, both for O2 sensor heater circuit failures....on both sensors 2 and 3.....but NOT on sensor 4. In other words, the 'logic' being communicated through the fault code being triggered by the blown fuse.....that, for some reason, seems to be incorrect. Maybe it's just an anomaly of my Wrangler...... or maybe it's the way the ECM is programmed to react under this kind of failure. But...either way..... replacing the down-stream O2 sensor on the front back may NOT be necessary if someone sees this code. May just be a fault in the wiring. Too late for me to go back and try to old sensor as I discarded it. But..... would be nice to have had it to try. Anyway..... it made it home with no 'check engine light'......and that's progress! Thanks again for the comments! WC
 

·
Registered
Joined
·
2,382 Posts
Warfcreek, that's the problem with codes.

Folks read them and think they point to a part. They don't, they point to a part of the system. And that's where things can go south. They don't understand that there's more to it then just a part. They toss a part(s) at it and it doesn't fix the problem.

And that's why there are diagnostic trees to follow for each code to properly diagnose the problem.

Not picking on you, just that it often isn't a specific part that fails.
Yours was a pretty easy one to figure out, you had a perfect description of a grounded wire and not necessarily a bad sensor. Why? The cold start.

That's when the heater gets activated to warm up the sensor faster then it normally would. After it's up to temperature the heater shuts down. And even if the wire is grounded there's no short to blow the fuse, and the PCM doesn't see a problem, as the sensor is doing what it's supposed too.

Glad you did track it down though.

I see this kind of thing every day at the shop. Read the codes for the customer and first words out of their mouths is how much is the part?

I explain the above to them and it's like they don't want to hear that, they want an immediate fix by replacing a part. It doesn't always work that way. That's when I tell em we can either fix it right, going through the steps, or we can do it their way tossing parts at it till it gets fixed.

Usually they will go my way, but there is always that one, more money then brains.

Last one, lets see if I can remember it all. Starter, battery, ignition switch, neutral safety switch, fuel pump, coil packs, module, injectors, spark plugs. This was a car that would crank over but not fire. Why some of the stuff I have no clue but he went and did it.

Would stop by the shop daily to ask again why it wouldn't start. And I kept telling him, without seeing the car I would check to see which of the three basics he was missing. Fuel/Air/Spark. Didn't matter, he did what he wanted to do. Last time I was in the middle of something with another customer, he barges in again. Rather then go over it again, I told him to go check the fuses, and continued on with the customer I was working with.

15 minutes later I see a car pull up to the shop. Wanna guess who it was, and what was wrong with the car from day one? ECM fuse was missing.
 

·
Registered
Joined
·
15,680 Posts
Plus one more basic can timing
Remember a late sixties v8 stang would cough but not quite start but had good air fuel and spark just the timing chain had stretched and jumped a couple teeth
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #8 ·
Speaking of cam chains, I had a boat motor once that had an odd problem: Long story short, after many attempted start cycles, it would finally start, run for about 15 seconds, then quit. The first few attempts to re-start would act as if the engine had no compression....which in fact it didn't. The final resolution turned out to be a 'rust' glob that had set into the bottom of the crank drive sprocket that drove the cam belt. This glob caused the belt to jump one tooth every revolution of the crank shaft. So, don't know how many total teeth we're talking here, or crank revolutions, but the short of it was that it would go 'in' then 'out' of cam timing....run, then quit. Fix: Remove the rust glob! Price to fix: $0.00. Lesson learned: Priceless!

thanks for the comments guys. Put over 100 flawless miles on the Wrangler today. Felt good to drive it around and know it was working properly! What a fun car to drive! WC
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #10 ·
Dig; yes it was! Had another odd-ball 'boat' experience once where, after sinking the boat out in Lake Erie, I had an engine problem with running at low RPMs after doing some basic refurb on a motor that had gone under water for a few hours. V8-283 motor in an old ChrisCraft. Had some of the best 'tech' minds in the State of Ohio working on it with me, changing heads, distributors, carburators, fuel pumps......all to find out that 'coincidentally' with sinking, the floor of the aluminum intake manifold had burned through in a spot not really visible easily even with the carb off. Hole was bigger than a pencil eraser but smaller than a dime. Anyway, basically just a big old vacuum leak at the cross-over for pre-heat on the intake. Took it in and had a guy weld it up and all was fine. But, again, you go after what you'd think would be the obvious problems arising from submerging a motor under water...... and you often fail to consider what might be the obvious cause of a problem had it NOT gone under water. In this case, an enormous vacuum leak.....easily diagnosable with a simple vacuum gauge. But, everyone involved kept thinking of things like cold water hitting hot valves and warping valve stems.....or 'electrical' problems from water intrusion. Anyway, the saying of 'spit happens' was pretty appropriate in that case as well.

I'm just glad to have my Wrangler running properly now......and feel like I can now get to some of the more fun 'options' I want to pursue with it. I'm about half way through doing an audit upgrade, it's going to need some cosmetic attention, I do want to address the wheel/tire situation, and I need a trailer hitch. From there, who knows. I'm told the cold air intake is a waste of time.....but I still think I want one. Oh, and then there's the matter of changing out all the fluids in the axles and trans components. At 175K miles, I think it deserves some high-quality lubricant in all the rolling stock, perhaps with some 'additives' for friction reduction? Any suggestions on 'best types' of fluids to go with would be appreciated. I'm a HUGE fan of Redline products and use them in my Harleys exclusively. Their Trans lube is incredible once you get past the part of having it look like Pepto-Bismal. WC
 
1 - 10 of 10 Posts
Top