1997 Mercury Mountaineer 5.0 P0141(this was reset button thread) | Ford Explorer Forums - Serious Explorations

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1997 Mercury Mountaineer 5.0 P0141(this was reset button thread)

allmyEXes

Elite Explorer
Joined
February 6, 2016
Messages
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City, State
No. Alabama USA
Year, Model & Trim Level
1997 Blue Ex 4.0 SOHC
Callsign
KAGG 3611 (CB)
I know that the PCM can be reset by disconnecting the battery for a short time to reset and I have been keeping my Scan Tool on the seat of the one that I am driving and reset that way however surely there is a simple way to install a reset button to do this and someone may already have. If any of you guys that have OBD2 experience care to chime in it would be appreciated. I think it could be as simple as installing a normally closed push button switch in one particular wire. Maybe the main power wire for the PCM? It might be a handy feature to reset when little annoying conditions cause the light to come on, reset and be able to replicate the condition to make it come on again. Just an idea and any positive input would be appreciated.
Edited. Start with post #7. Thanks
 



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why not just clear the codes with the OBD2 scanner?
 






I addressed that in the original post. Maybe instead of a normally closed pushbutton reset switch a SPST switch to interrupt the PCM relay power and it would also serve as an anti-theft device. It could be labeled as Fog Lights to confuse wouldbe CH MH thieves...
 






Honestly, I think the time to fix the cause of the CEL would be more effective, because to be honest I never have to reset my PCM. Depending on what is going on, repeated PCM code clearing and resetting could just result in an expensive fix later.
 






I use my old Scan Gauge to clear the one P0125(coolant too cold) code, maybe once a day. That doesn't reset the PCM's learned conditions, it just erases the stored codes.
 






@allmyEXes
Certain codes cannot be reset. Or deleted by scan tool. "Permanent Codes", required after I think 2009 by the Feds, can only be cleared by the PCM itself, IOW, it must determine code cause has been actually repaired.

I have one such code illuminating my ABS light: "VIN Code Mismatch". It's there even after I stand on my head! imp
 






Everyday in my 1997 MM 5.0, I have to check it and clear P0141. The 5.0 engine is not running rough and it's getting 15 MPG. I guess that I could have a damaged wire down that way. This would be bank 1 (passenger side of the engine) It happens to be the bank that still has the old plugs and wires. I guess that I have something to do this afternoon now that I can get in the Shop Building. Yes, I can hear y'all it may have nothing to do with the P0141 DTC, but surely I am confusing the PCM with new plugs and wires on one side and not on the other. No, I didn't halfazz the repair, I did what I could under the conditions that I was in. This all started when it started missing and posted a P0307 DTC, misfire on cylinder 7. I changed the #7 plug and it still misfired. Changed that wire (brand new Motorcraft set) tried it, no more misfire. Changed the remaining 5-8 plugs and wires. Ran out of light and tolerable temperature. The old wires were original 21 years old (250K miles) and the plugs could be too. they measured .105 plus. For those of you that don't understand thousandths .125 is 1/8". I know that mismatched old and new is not good for it, particularly the coil packs however I am delicately driving 4.75 miles one way to work and the same back home. But this afternoon is finally the day to finish the basic tune-up task.
:burnout:
 






P0141 you need a downstream oxygen sensor pass side
The heater circuit failure almost always means a bad 02 sensor
I know this sensor is a PITA to replace but it can be done. Getting the wiring clip on top of the trans can be a pita, if you have to, remove the drivers seat and center console to gain access OR just the center console and cut the carpet (I love this mod on the V8 trucks).

Usually I can get the sensor unclipped by hugging the 4r70w and get your hands up there to work blind magic

A "reset" button would be pretty simple, just a button that disco's the PCM power feed for a couple of seconds should do it....we would just rather see you fix the code then add a button, and wiring
 






So am I correct to assume if I unplug it, clear one or all codes and drive down the street and back and access the PCM DTC codes it should post a P0140? which is 02 Sensor Circuit No Activity Detected (Bank 1 Sensor 2)
I see a 2 post lift in my near future...
Thanks for the encouragement...
 






After the drive home tonight I accessed the DTCs and a code P0174 popped up. Earlier I all but ran out of gas on the way to get some (gas). I suppose it could have been running very lean?
 






After the drive home tonight I accessed the DTCs and a code P0174 popped up. Earlier I all but ran out of gas on the way to get some (gas). I suppose it could have been running very lean?
@allmyEXes
I wouldn't think so. The "throwing of codes" is closely governed by how long the deficiency has existed, how frequently it recurred, and how consistently have those same conditions presented which call for the code throw. I have info buried somewhere regarding the actual way in which code presentation is governed, but don't think it will help here. Academic. imp
 






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