Maintenece required light just came on :(

[noskils32]

Cold Air Intake Noise

Hey all, last night in Monterey my maintence required light came on. I drove about 80 miles north to San Jose. It did great, especially over highway 17 (steep, windy road for those of you who don't know california) but I am still kinda woried about it. I checked the oil and it was fine. Anyone have any other ideas of things to check for so I don't have to take it down. I doubt that it has a computer that can have a diagnostics check done on it since its a 91 yj. Anyone had this before? Thanks.

 

[LVRockCrawler]

hey eric...
what year and how many miles? my old 91 w/the 4.0L did it to me on the way to Atlanta (when i still lived in florida...) - I pressed on w/it glowing in my face, no problems, got back to Orlando and took it in to the dealer... they told me it is a scheduled thing (certain mileage) and the only way to reset it is to hook it up to a diagnostic machine...($40, 10 yrs ago...) - check to see if yours is the same deal (came on, wont go off???) - if it is, the best fix is to pull the bulb for all the good that light does...
hope that helps...

bob

 

[noskils32]

XJ lift questions

1991 YJ with 82000 miles or so

 

[LVRockCrawler]

That was pretty much when mine came on - bet its nothing - call the dealer and ask.... if they are honest (yea... okay... i know the odds) they'll tell you what the deal is...

 

[LVRockCrawler]

is there a "check engine" light also? i dont remember - but if there is, thats the one to pay attention to...

 

[_(OIIIIO)_Jeeper]

disconect your Pos (+) post on your battery for about 10sec....see if it resets itself.

 

[jps4jeep]

Mine came on at about the same milage. now I have 115K and it came on again, but thats cause the black electrical tape I put over it at 85K fell off! simple fix, a little more electrical tape!

 

[BostonJeep]

so wait we got a check engine, and a maintence required light?

im at 81k and havent seen Maintence one yet. the check engine one on the other hand.... no need for electrical tape i think the bulb burnt out.

 

[noskils32]

OK, electrical tape it is! Thanks a lot guys!

 

[TwistedCU]

The "Maintenance Required" light is tripped by the odometer. It is there to tell you it is time to replace the mass oxygen sensor. Mine went off at just over 80k miles also. If you have it reset using the computer, it will go off again at a little over 160k miles. There is no other way to reset it other than the computer, I left my battery disconnected for a whole weekend to no avail.

It is technically illegal to modify but my bulb somehow worked it's way loose. Not sure how though :wink: It's also illegal to reset without changing the sensor.

The Check engine light is totally different, if it lights up there is at the minimum a bad sensor.

 

[XJNick]

Hi,

Yes, on early YJs and XJs, the maintenece required lamp (it reads EMISS MAINT on the cherokees) IS triggered by a clock. It, however, is NOT the odometer. It is a separate electro-mechanical timer (which on cherokees is under the steering column), which runs anytime the Ignition switch is in RUN. this timer is geared so that it trips around 80,000 miles -- when the 02 sensor(s) are supposed to be replaced.

The timer is not supposed to be resettable after it has tripped, so your best bet is to either A) replace it (not worth the money -- plus it'll go off in another 80K miles) or B) unplug the 3-pin electrical connector from the timer box (disable the lamp for good).

This will have no negative effects on the Jeep as this timer and lamp are completely stand-alone and in NO way connect to the computer system. :mrgreen:

Note that this info is NOT valid for TJs or XJs with OBD-II computer systems ('96 or newer)

-Nick :!:

 

[TwistedCU]

D'oh!! ... D'oh!!

IS triggered by a clock. It, however, is NOT the odometer. It is a separate electro-mechanical timer

Right and wrong - 1990 was the last year for that timer!
:wink: This is at least true for the YJ, I have no idea as to the XJ.

Noskils, your 1991 is in the PCM (powertrain control module) and it can be reset with a scanner.

 

[XJNick]

Right and wrong - 1990 was the last year for that timer!
:wink: This is at least true for the YJ, I have no idea as to the XJ.

I guess they used them longer in the cherokees. It was a pretty useless circuit :roll:

-Nick :!:

 

[jeepinstien]

My 91 yj had the mechanical timer. electrical tape is a good fix. Auto zone has the reset proceedures on their computer if you don't like tape.

 

[TwistedCU]

my new jeep.

Since it can be reset by their computer, that proves it to be in the PCM, not a mechanical timer.

any pre-91 YJ would have the mechanical timer which can't be reset (see above post by XJ Nick).