Check engine light issue

Jan 5, 2019
14
Brenham, Texas
Bought car recently. Wangler runs great and looks good. Well cared for. I can't honsily say if it showed engin light when I purchased it. I know not to swift. I know most people are worried if engin light is on. Mind never shows. Took out instrument cluster to check if light blacked out or burned out. Light is a diod. Going to take cluster back out and check if connector pins or wires been mess with. I can tell cluster has been out before. Bottom cowling tab broken. Not very likely diod burned out. All other check lights show as they should. Carfax showed car passed emmission testing in the Dallas Texas area at 65,0000 miles. Watching gas consumption for miles per gallen. Trying to get schematics now. Still love car. Just don't want something later to bite me because I did not track this down. Thoughts and help appreciated.
 

Chris

Administrator
Staff Member
Sep 28, 2015
34,476
Salem, Oregon
Come again? What's the question?

I'm reading your original post, and it just doesn't make much sense at all.
 

Jamison C

TJ Padawan
Supporting Member
Sep 1, 2018
259
Sedona, AZ
It's possible. I'm concern the engine light was disable because of other problems. The Jeep shows sensor codes.
I’m assuming you mean trouble codes when you say sensor codes? You can do a couple things.

1. Turn the key on and off three times without starting the engine. When you get to the third time leave the key in the “on” position. This will display any error codes your Jeep might have on the odometer readout, assuming you have any.

2. It’s pretty unlikely the CEL light burnt out, though not impossible. Swap it with one of the diodes that you know are good like blinkers, brights indicator, etc.

3. Sometimes a bad or failing ECM will not illuminate the CEL when the key is set to “accessory ON.” We had an old Mercedes that took around 10 minutes to start. The excessive cranking heated it up enough to eventually get it to run. We thought it was the cold start valve not adding enough fuel but we noticed the CEL never came on when we turned the key to “on.” Swapped in a used (expensive) computer and it started right up first start. I’m not too knowledgeable on the Jeep ECM but it’s always possible. The odometer trick I listed above might show ECM codes. I know other vehicles do.

Hope this helps.
 

mrblaine

TJ Expert
Supporting Member
Nov 20, 2015
3,397
Quail Valley, CA
Any time there is a question as to whether someone has monkeyed with the cluster lights, you can run a diagnostic. Push in the trip meter button before you turn the key to ON. Unlike the video, you don't have to continue holding it in once the test starts.

 
Reactions: Red Dog

mrblaine

TJ Expert
Supporting Member
Nov 20, 2015
3,397
Quail Valley, CA
Damn, this is what i like about this forum, I learn something new every time I log on. Did not know about that diagnostic function.
It is helpful. We should always bleed our brakes with the key on to watch the brake light on the dash to see if it is being tripped. Just had one that the parking brake didn't trip it and the switch on the combo block was unplugged. It can't plug in since the block has been changed. The switch on the parking brake was faulty.

We fixed the PB switch, no light. Fixed the combo block, still no light. Diagnostic showed the light was not present. Pulled cluster and added a light, now it all works as it should. PIMA.
 

CaliSteve

TJ Enthusiast
Mar 29, 2018
162
Southern California, CA, USA
It is helpful. We should always bleed our brakes with the key on to watch the brake light on the dash to see if it is being tripped. Just had one that the parking brake didn't trip it and the switch on the combo block was unplugged. It can't plug in since the block has been changed. The switch on the parking brake was faulty.

We fixed the PB switch, no light. Fixed the combo block, still no light. Diagnostic showed the light was not present. Pulled cluster and added a light, now it all works as it should. PIMA.
It is helpful. We should always bleed our brakes with the key on to watch the brake light on the dash to see if it is being tripped. Just had one that the parking brake didn't trip it and the switch on the combo block was unplugged. It can't plug in since the block has been changed. The switch on the parking brake was faulty.

We fixed the PB switch, no light. Fixed the combo block, still no light. Diagnostic showed the light was not present. Pulled cluster and added a light, now it all works as it should. PIMA.
Can only imagine the tail chasing you have to do at times, you do have a valuable skill set mrblaine!