Help! Need a PCM or repair

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N8N_99xj

NAXJA Forum User
NAXJA Member
Location
Curtis Bay, MD
Need some help guys. For about a year now my '99 XJ (4.0/Auto/232) has been slowly running crappier and crappier. I KNEW it was a wiring harness problem. Took it to two shops neither of me took me seriously. Finally broke down and took it to the "real auto electric shop" 60 miles away and the guy there is fantastic. However he's fixed the harness but somehow the PCM died. He said it's a 492AE and he can't find one anywhere. He's tried two 493ADs and apparently they're different enough that it won't work. One would accept the mileage but not the VIN and the other would accept neither. Problem is I have a CEL now with a P1495 code for leak detection pump and I don't have a leak detection pump. Can anyone help either let us know how to code the "new" PCM or can sell me a PCM that will work? Otherwise I'm going to have to scrap an XJ with only 120K miles on it because I can't even park it in my driveway unless I can pass emissions. I can't get a waiver because the shop is in MD and I live in VA (but there are no good shops in VA near me that I'm aware of) Thanks!
 
The two letters at the end are just the software version and wont significantly effect the function. The letters (492) is the important part and it needs to match what was there originally.

In 1999 the difference between the 492 and 493 is that the 492 is federal emissions and 493 is California. Thats why the 493 is looking for the leak detection pump that is not there, you need a 492 PCM. The 493 will run, but will be looking for a leak detection pump that is not there, and thus will throw a code which sounds like what is happening to you.

Used PCMs also don't need to be programmed and the PCM does not effect the miles on the odometer (that is stored in the gauge cluster itself). The PCMs are plug and play. Plug it in and it should work. If it doesn't then its defective, or you have other wiring issues.

Theres really no reason to pay a mechanic to do this either, its 3 screws and 3 plugs, pretty easy.

I have a spare 492AD that I would sell if you are interested.
 
It is sitting at the auto electric shop primarily because I've been too busy to attempt to fix myself, and the guy really did fix the main problem which was a f**ked up wiring harness, I have no good work space either. He's telling me it shouldn't be a big deal but he does need to input the VIN and mileage into the PCMs.

thejeepgod, it sounds like you are really onto something there. You are correct, my vehicle does not have the leak detection pump. Guy is saying that the vehicle runs fine now but has the code which is killing me because I can't even bring the thing home or I'll get a ticket (damn Loudoun county cops, my reg. expires end of the month. They WILL go into your driveway and ticket you for an expired reg even if you are not driving the vehicle, happened to my roommate on his pickemup truck. Can't reregister until I get the CEL to go away.)

I really don't know how this works, are AD and AE different rev levels, and the 492/493 are the different versions? If you are fairly confident that your 492AD will work in place of a 492AE that is the best lead I've had yet please send me a PM

thanks!
 
If the shop guy cannot reprogram a 1997-2001 OBD-II computer, I wonder about his technology skills, especially if he killed your original PCM.

Is the P1495 caused by a faulty or an incorrect 493 PCM ?

I have a spare 492AE PCM, send a Private Message if you are interested.
 
Tim_MN said:
If the shop guy cannot reprogram a 1997-2001 OBD-II computer, I wonder about his technology skills, especially if he killed your original PCM.

Is the P1495 caused by a faulty or an incorrect 493 PCM ?

I have a spare 492AE PCM, send a Private Message if you are interested.
Click to expand...

Yeah, the original codes were nothing like P1495 they were something related to the MAP sensor and also one of the O2 sensor heater circuits. I suspected a harness problem as at the same time all this started my "PART TIME" light stopped working as well. P1495 only showed up after he replaced the PCM.

I'm sending you a PM now...
 
Just a FYI,,,,, NAPA has reman PCM,s for your XJ.
 
Just drive it to a county in Virginia that doesn't require emissions testing. I live in Virginia Beach and we don't have to hook up our cars

Sent from my XT1585 using Tapatalk
 
I don't know what to do now

he's saying he installed the 492AD PCM and it's still throwing a code for the leak detection pump that never was there

He's also telling me that the original PCM was a 493AE not 492AE as he told me last time

Basically he's got four PCMs, one (the original) is dead and the other three all throw the leak detection pump code (1x 492, 2x 493)

WHAT THE HECK DO I DO

I seriously need this fixed within the next week or it's going to get scrapped because I can't have an unregistered vehicle
 
Man, I'd go back to the start and swap the harness for a good one.
If it's not the pcm and you don't have a vacuum leak to a pump since you don't have a pump I'd go back to where the trouble started.
Before that I'd verify the original PCM numbers have been matched.

There is a similar thread for a GC where the dealer diagnosed it as a harness problem, I think his issue was dry rotted hoses but his jeep had this pump, I'm assuming yours doesn't .


Sent from my iPhone using Tapatalk
 
I don't know where I'd find a good harness, and my reg runs out end of January

Im guessing my repair bill at this point is close to the value of the vehicle. Guess I'm done. Sad. Facebook reminded me that I got it 5 years ago today :/
 
I'm only guessing, don't know much about the 96 up XJ. From what is described and if the replacement ecu/pcm is correct, I'd go back to the first problem.
I'm not sure if it's 99 only for the harness, somebody here will know. also somebody here may possibly have the harness you need.

Using car-part.com 99 cherokee searched for Electrical Part Misc and Wiring, several placed show wiring harnesses, matching them up to your jeep would be the trick (all the options)
These are only the junk yards that show this part online, which means they bothered to inventory it, most don't, and many yards do not show inventory online at all.
Hope these help. again I'm only guessing.

http://recycler.car-part.com/GMILLNJ/ has a 99 harnesses 4.0,EFI,4x4,Factory

http://recycler.car-part.com/Dansers/ Dansers Auto Repair & Salvage USA-PA(Greensburg) shows a engine harness

http://www.tripledeckerautoparts.com/ Triple Decker Auto Parts USA-VA(Chesapeake) shows a 2wd engine harness

http://www.cjautousedparts.com/ CJ Auto Used Parts USA-NC(Macon) shows a engine and dash harness but no details on which engine or drive train

http://www.northjerseyaw.com/ North Jersey Auto Wreckers USA-NJ(Andover) shows a harness

http://www.topnotchservicecenter.com/ Top Notch Service Center USA-NC(Edenton) shows 2 engine harnesses

https://www.hollanderparts.com/used...ness/648.am8299-alternate-engine-wire-harness
Hollander used parts search may have few different junk yards.

Ebay has a 2000 harness which I don't know if it will work for you
http://www.ebay.com/itm/Engine-Wiri...ash=item1c79e1e214:g:YLwAAOSwo4pYcvOT&vxp=mtr
 
Last edited:
493AE was the original pcm?
that should be a low emission jeep then, but a used parts search can show supposedly fed emissions jeeps with this #. weird, although many junk yards guess at emissions when doing inventory based on their state so maybe it's not out of the ordinary.

Might be a good idea to decode your vin to be sure what you have. Just spitballing.
 
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