1999 Jeep Grand Cherokee check engine light problem READ BELOW?

Question

So I've had to replace the cam and crank sensors and the Check engine light has never come on. Not even for a misfire! The light works. Whenever I turn the key it glows for when I start it. Is there any way I can test to see if it works?

Answer 1

When you turn the key on, you'll notice a bunch, if not all the dash lights come on for a couple of seconds. This is a self-test the computer does to make sure all the lights are working. That's how you check to see if the engine light (referred to as the malfunction indicator lamp (MIL) among technicians) is working.



The check engine light comes on when the powertrain control module (PCM) sets a diagnostic trouble code (DTC) in its memory. In all vehicles in the States built in 1996 and after, this system is known as OBD II, and in every said vehicle, there is a 16 pin, trapezoid shaped diagnostic port located no more than two or three feet from the steering wheel, and usually it's under the dashboard. You can take your Jeep to a place like Autozone and they will plug a scanner into it and retrieve the DTC's for free and even give you a print out along with a short thumbnail troubleshooting guide to point you in the right direction towards resolving the problem causing the DTC to be set and the MIL to illuminate. You can even purchase your own scanner to use. Depending on the level of sophistication of the scanner determines how much it would cost. You can get a decent Actron brand scanner for around 200-400 bucks.



If the vehicle misfires just a little bit, that normally won't set a DTC and light up the MIL. It would have to be a more severe and consistent misfire for the PCM to detect and set a DTC. Good luck.

Answer 2

Turn the key to ON (not start engine)

Turn the key to OFF

Turn the Key to ON

Turn the key to OFF

Turn the key to ON and leave it. Give it a few seconds and it will display the codes in the odometer and the CEL will flash.

That is how you test a CEL and display codes on a 1999 XJ. Google the numbers it displays. 55 means nothing is wrong.

Answer 3

The first answer is the best most thoroughly answered question, and you should do exactly what it suggests.