MVTitan

Hope this helps someone...

Ran into a repetitive "Check Engine" MIL light after 62,000 miles with a small rough idle. Took the Cherokee to the Chrysler dealer and they insisted it was my gas cap causing the light to trip...which I found odd since I found out later the actual PCM code was Leak Detection Pump related. Gas cap replaced and light came right back on after 2 engine start/off cycles.

I broke down and purchased an Actron OBD II Auto Scaner and down loaded code P1494 "Incorrect input state detected for the Leak Detection Pump (LDP) pressure switch." Went back to the same Chrysler dealer (without the vehicle) and inquired about the code and was told the LDP swicth was bad and had to be replaced (part alone was $119.00).

Went back to the Jeep and started from the bottom up trouble shooting on my own after internet research. If it was a faulty LDP, then Code 1495 would have tripped. Started with inspecting the vacuum lines first and found the problem. There are two vacuum lines that run from the passenger side of the engine bay from the LDP, along the fire wall, to the drivers side of the engine and connected to the engine manifold (bellow the air fiter intake duct). One of the 90 degree boots became deteriorated and fell off the manifold coupling. Replaced the elbow, erased the PCM code (MIL light) and its been 2 months now with no repeat occurrences.

Attached is a link to a Emmisions Control document loaded with usefull to include PCM codes which also applied to Cherokee Jeeps I found on the internet. http://www.scribd.com/doc/3503856/Jeep-XJ-2000-25-Emission-Control-Systems

Bottom line, the certified Chrysler dealership mechanics are not always right and I hope this info helps anyone else in the future. Always check the obvious first before spending money on replacing parts that are still serviceable.

Turbo x

Thank you , that was the problem , my hose came off the manifold.

gavilan

I had that happen to my 2001 as well, but I actually borrowed one of those simple computers from Kragen (or Auto Zone?) and tried the first (and cheapest!) thing that the code stood for: the faulty gas cap.
Bought a new one and then had the check engine light on again and it was time for a smog test anyways so took it to a car shop and they found the broken lines and replaced them.

I'm surprised the dealership tried the cheapest first... lol

MVTitan

Yes, nothing like having a "certified" technician throwing darts at a troubleshooting tree...lol.

sh1pyardT3ch88

Thanks for the link, it was immensely useful.

97grand4.0

Yeah it says was deleted, like 9 years ago. Thanks anyhow.

laytox

Got this code, googled it, this was the first thing that popped up, and is exactly what was wrong.

I know this is an old thread but does anyone have a part number for that elbow?

gat

To find the part you can either go to moparpartsoveretock.com and enter you vehicle and browser for it or go to the Doorman Help section of O'Reilly's.