OBD-II question - CEL came on again, 2 codes this time

[Geonovast]

Check engine light came on in the 99 XJ today, about 10 miles before I got home. I stopped at the only shop I know of on the way, but they were closed.

 

Temp, Volt, and Oil pressure gauges all read fine. It did seem to lose a bit of power when it came on though, although not enough to cause a problem.

 

Is there any kind of jumping trick I can do to get it to throw me a dash code, or do I need a scanner?

[Automan2164]

Don't know if the key on key off 3 times trick works on the newer XJ's... But that's worth a shot.

 

Rob L. :dunno:

[HOrnbrod]

You'll need a scanner Corry. Autismzone and others will plug one in and scan it for free. I have the codes for Jeep OBDII, but whomever (whoever?) scans it should also, but let me know if I can help. :cheers:

[jeepdoggydogB]

Don't know if the key on key off 3 times trick works on the newer XJ's... But that's worth a shot.

 

Rob L. :dunno:

I think the key trick worked on up to 1997 Jeeps, my wife's 1997 Grand Cherokee would display codes, and my 1998 TJ needed the scanner.

[Geonovast]

How does this trick work? I turned the key on and off 3 times, but it didn't do anything.

 

I'll give O'reillys a call and see if they'll scan for free. Closest autozone is 45 minutes away.

[johnnyc]

Do you have a Harbor Freight near you? They have several inexpensive code readers. When I had my 98 XJ, I kept one of their $20 readers in the glove box. It came in handy many times. I could plug it in and get the codes while driving down the highway.

[Eagle]

:agree:

 

OBD-XYZ is here to stay. The scanners that Harbor Freight now sells for $29 or $39 are infinitely better than the brain-dead unit they sold for $49 (on sale) just three or four years ago. But ... don't buy the cheapest one they have. Spend a few extra $$$ and get one of the ones with CAN [something], so you'll have more flexibility to use it on newer cars -- whether your own, your family's, or your friends'.

[dfreeman616]

once you find out the codes, throw them up on here and one of us can probably help you figure it out if needed.

[Automan2164]

We bought the Escan at work. Its a PC based scantool with light signal graphing. Its a really sweet tool on OBD II vehicles. It will map out the fuel trims to show you if its running lean through the range of RPM, the graphed signal of the TPS, or anything else you might need. It will read Mode6, which is the computers language for emissions testing. Its an AWESOME tool to use when emissions testing, since it will tell you when the computer has completed its self checks, and when its ok to take it in without it puking a "Readiness tests not complete."

 

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It was $700, but its been well worth it for us.

 

http://atsnm.com/escan.htm

 

Rob L.

[dfreeman616]

Rob, why must you tempt me with more tools? :fs1: That would be nice...

[Geonovast]

No Habor Freights near me(not that I know of, anyway) I pass one in Madison on the WI/MO trip..

 

I called O'reillys, and they said that they don't do the scan... but they give me the scanner and show me how to use it. Dunno if that's just a lend in the parking lot thing, deposit lending, or if that means I buy one there.

 

Rob, why don't you bring that $700 fancy piece of machinery down here and leave me alone with it for a few hours? :brows:

[87Warrior]

I know AutoZone will scan then give you a print out of the codes with possible solutions. The downer is you have to deal with AutoZone people.

 

In my 03 TJ I can turn the key 3 times and the codes will show up in the odometer.

[Geonovast]

Just got back from Oreilly's, they let me take a scanner outside and hook it up. Didn't give me any numbers, but said "Torque Converter Clutch Circuit Malfunction", which I didn't get, because the converter's been locking and unlocking just fine.

 

I cleared the code, and it didn't come back on on the way home.

[mythreesons]

Rush hour traffic can be a pain in your area (all six cars worth). :D

 

Maybe between your lead foot on the skinny pedal and the wide pedal it got cornfused with the brake pedal switch and what it should be doing?!?!?!?!? :dunno:

[HOrnbrod]

Never had that code on my former 96 or 01 XJs. Did a search on "aw4 code p0740 jeep cherokee" and the most common fixes were a bad TPS or simply changing the tranny fluid.

 

http://www.cherokeeforum.com/f2/code-p0740-torque-converter-shot-35461/

[Geonovast]

I'll see if the CEL comes back on or not. It's been shifting normally, and locking normally, so I doubt it's got anything to do with the TPS. It's got its power back too since I cleared the code. :dunno:

[Geonovast]

It came on again. 2 codes.

 

Torque Converter Clutch Circuit Malfunction again, so gonna have to look into what the problem is now.

 

Also got Evaporative Emission Control System Purge Valve Circuit Malfunction..

 

Eh?

[terrawombat]

Also got Evaporative Emission Control System Purge Valve Circuit Malfunction..

 

Eh?

 

When I first saw your post, I assumed your CEL would be caused by the evap. emissions system since all three OBD-II XJ's I've owned have thrown that code. The '99XJ I had threw that exact same code while I was driving it to it's new owner's house (and before I had the money for the vehicle). Luckily it was my girlfriend's mother so she was very understanding about it :D She said her mechanic fixed it by replacing some vacuum lines underneath the truck, which I assume were the ones going to the charcoal purge canister.