2002 Explorer 4.6 Eddie Bauer

I just got this truck. The check engine light hasn't worked from day one for me. Here's what I've done so far.

I checked for a burnt out bulb. The check engine light is a LED that's soldered to the circuit board. Had both resistors and the diode tested, and they work. Unsoldered the bulb and tested it too. It works. There is no obvious damage to the board.

There is a 5A fuse. The fuse is fine. The 4x4 module runs on the same circuit, and it works fine.
However, the 4x4 module does not run through the micro-processor in the cluster. Two other circuits do. Listed as "check gauge" and "charge"(battery light?). I am not sure what these are.

There is no obvious damage to any of the under dash wiring.

I swapped in a spare cluster, and almost nothing on it worked. Possibly the cluster needs to be programmed. Not sure.

I swapped in a spare ECM. I knew it wouldn't start the car, but figured it would at least light up the cluster. It does, but not the check engine light. I only checked it with the original cluster.

I went and bought a factory wiring manual. While I am able to see the wiring for the LED in the cluster for the check engine light, it isn't mentioned in the plug diagram, or anywhere else in the manual.

Has anyone else had this issue?

I can post wiring diagram pics if necessary.

 

Are you positive the anode and cathode are correct in how the LED is installed on the board? I'll admit, I'm surprised to learn the CEL uses an LED rather than a standard bulb on the 2002.

Check Gauges would illuminate in the event of low oil pressure or high coolant temperature. Charge would illuminate if the alternator is experiencing issues.

-Rod

 

Yes, I didn't remove anything except the LED bulb. I only tested them with a meter to see if the correct amperage was coming through them. Aside from the turn signals and background illumination, all the other bulbs in the cluster are soldered on LEDs.

I did get this issue resolved today. By accident. I was using a test light to test all of the wires in the two harness plugs. I was looking for a light that only stayed on momentarily. I guess I must have cleaned off a dirty connector. When I plugged it back in, the check engine light started working again.
And I just ordered a replacement fuse box too. Oh well.

I've had this cluster in and out about a dozen times in the last four months so it took more than just jiggling a plug.

The car has been a nightmare so far. Catching up on all of the past years neglected maintenance. Almost there though. At least I can say that I know more about the workings of the explorer than I expected to in a very short amount of time.

 

I'm glad to hear you got the light working, at least for the time being.

-Rod