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Check Engine Light from "thumping" Dash with fist?

Lost_Wrench

NAXJA Forum User
Location
CO
Was driving my '98 XJ the other day and I noticed that when I turn on my headlights the left blinker arrow also illuminates now. Both blinkers still work inside and outside its just when the headlights are on, the left arrow is solidly illuminated as well. Annoying. I tried wiggling the turn signal switch a bunch and then (out of frustration) I hit the top of the dash with a closed fist. Not terribly violently, just a single thump. At the exact moment I did this the Check Engine light came on for the first time since I've owned the Jeep. I put the scanner on it at home and I got three codes.

P0743 - Torque Converter Clutch Solenoid Circuit
P0138- O2 Circuit High Volt, Bank 1, Sensor 2
P0700- Transmission Control System

I have zero problems with the Transmission. Jeep runs fantastic. I am however having a problem with the transfer case but that seems unrelated to those codes? Fuel economy is good and I don't have emissions where I live, so O2 sensor problem is also unnoticed.

Could the Check light have been "on" for a long time, but me hitting the dash somehow allowed it to finally illuminate from a loose connection to a bulb or something? I feel like the timing is far too coincidental. And yes, I know hitting your Jeep is bad. I apologized already.
 
Dis-assemble the cluster and re-install with some anti-ox, there was a TSB on this.
 
Thanks I just looked up the TSB's for the '98 and '99 Cherokees. I think I found the one you are referencing, TSB 183197 for CONDITIONS ON OBD II MISFIRE MONITOR.
 
If the CEL is valid, there will be pending or stored trouble codes when checked with your OBD-II trouble code reading device.
 
There are, I listed them in my first post above. I just don't have any driveability issues related to those codes so far as I can tell.
 
Solve the P0138 and see if the other trouble codes clear up also.
 
Update:

Solved the P0700 (transmission fault detected) and P0743 (torque converter solenoid) by replacing my transmission filter and all 3 solenoids including the torque converter solenoid. I had first checked all of the wire harness connections going from the engine bay to the transmission and they all looked fine. I never did have any noticeable driveability issues related to the transmission, and I tried clearing these codes several times but they just came back immediately upon startup.

A few side notes about that job. . .

-In some write-ups I viewed people had trouble separating the dipstick when lowering the trans pan. On my '98 it separated nicely about 6 inches up from where the tube goes into the pan. No tools needed it just has a tapered fitting.

-One of the solenoid mounting screw holes on one of the new solenoids from the kit I bought did not line up perfectly with the threaded hole in the transmission where it seats. This really confused me because the other two were perfect fits and the solenoids are direct fits with no wiggle room once you plug them in. I ended up having to grind out the hole for the screw on that solenoid a little bit to get it to line up with the threaded hole. That really worried me that I may have gotten the wrong kit or part or something because had I not grinded it a little, the mounting screw would never have fit. Strange manufacturer defect I guess. Everything runs fine btw.

-My fluid was dirtier than I thought. I cleaned a lot of nasty sludge off of those two magnets on the bottom of the pan. Also, my fluid smelled bad. Couldn't tell if it smelled burnt but it had a smell almost like pickle juice. I have 183k now and I could tell that the filter had been changed at least once before because the pan had a rubber gasket instead of the red rtv from the factory. The pan bolts were very loose...i could turn many by hand so not sure if they got tightened to torque spec from whoever did that job last.

After this job I still had the P0138 code and that cleared with a new downstream O2 sensor.

Backstory from original post:

I had no Check Engine lights until back in January when I hit the top of my dash with my closed fist, and at that exact moment the Check light came on. My theory is that it had been "on" for a long time and hitting the dash caused the Check Engine bulb to illuminate again, possibly from a loose connection at the bulb itself. Prior to this I did remove the cluster and clean the connection/inspect bulbs like someone suggested but it all looked fine, no corrosion anywhere.
 
I think your Jeep took that fist thumping personally and decided to get even with you.

;)
 
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