Darn that check engine light

[palerider]

The check engine light (CEL) is constantly on. What is the most expensive part that might be at fault, and what is its cost?
Should I have the service dept hook up their wires (for $65) to find the culprit, or should I go at it by checking one at a time the most common at fault parts?

I just bought: '98 Laredo SE, 5.2, 4WD Quadra-Trac, power everything and heated seats, sun/moon-roof, 83k miles.
Have had to: repair under-hood light (corrosion on brass housing terminals), wash mud out of license plate lights (lost of gravel road dust somehow got in and some moisture), do (me) an 8 hour detail job on the car interior and in the engine compartment.
It also needs a front wheels alignment and brake job, and will have to replace the front tires in a few months.
Otherwise it is in really good condition for a car that is 7 years old and the previous owner has three small children that left lots of half eaten cookies, candy-bars, and really mashed into the carpet chewing gum.
The only damage to the upholstery are four tears on the door-side of the driver's seat (leather).
The Jeep is: white exterior (in showroom condition and that is remarkable for a gravel road driven car) and dark gray interior (in excellent condition).

And, is the Quadra-Trac all time 4WD system as good as the owner's manual says it is in snow, ice, sand, etc., and is it as good as a manually operated system.

Thanks for any answers and/or opinions.

[southtj]

Hey and welcome to Jeepz. I believe that you can take it to AutoZone or a similar shop and they will check your Jeep for free and tell you why the check engine light is on.

As for the Quadra-Trac, I have no experience with it but I'm sure someone here has.

Sounds like you got yourself a pretty nice new Jeep. Welcome to the addiction.

[palerider]

Thanks south442. There's an Autozone just down the street from me, so if I get out in this 27 degree weather today I'll stop in.
I think we got a good deal as for price, condition, and is fully loaded, but that light causes some concern. And, I just wonder about the Quadra-Trac. I've had a floor-shift 4WD and a push button one, so this all-time system causes me some wonder.
Maybe, and hopefully, somebody will respond with news that it is better than those with shifters or buttons.
Oh yeah, is it alright to tell what we paid for it?
Thanks again for the welcome and nice words.

OH YEAH! That is one nice rig you have! I wanted a Wrangler but couldn't afford the thousands above what we paid for the Laredo. Maybe someday though.

[ROGLSTUBB]

My two GC's do not have quadratrac, but my mother in law and sister in laws GC's have it. They do no much serious wheeling but lots of dirt roads, ice and snow and they have done well. They work well for someone who is does not understand the uses of part time and full time and when it appropraite for both. The only negative I have heard is that the CV joints and transfer cases wear out faster and reduced gas mileage because of being constantly in 4WD.
But your purchase is not very old so unless it has abused it will do fine for several years to come. The two people I know that had problems with CV joints were approaching 200,000 miles on the jeeps.

Welcome again to Jeepz

[_(OIIIIO)_Jeeper]

Welcome to JEEPZ! :P Good luck with the infamous CEL!

[palerider]

Thanks south442! I went to Autozone and they plugged a hand-held diagnostics device in under the dash. After a few minutes, the display read P0720 speed sensor defective. I asked if they have the part, where is it located on the car, and could a guy like me with lots of tools change the part out.

Results: they had the part, cost a few cents short of $25, they said it is located on the side of the transmission.
I bought the part, went home, layed down under the car, screwed out the defective one (lost some fluid in a drip pan I put under the transmission) with a one inch socket, put in the new one, cranked it up and went for a drive. The CEL stayed off. Man, do I feel better now!

Thanks a bunch!! I'm sure that besides me there are many readers who didn't know that the parts stores can diagnose a problem. I wonder how much money you saved all of us today, or in the future.

Thank you too ROGLSTUBB for the info about the quadra-trac. I feel better now.

I put a short-cut to this website on my desktop so I can come back here quickly to learn more about Jeeps.

[southtj]

Awsome! It always feels good to be able to fix something yourself rather than paying someone else a fortune to do it.

Come back and visit. There a bunch of great Jeepers around here.