Check Engine Light not working - question

[endo1]

Hello all.

I just became an owner of a 2003 4x2 Sport V8.

The check engine light does not seem to be working, it won't flash on when startup and thus won't pass inspection. It is also throwing of O2 sensor error codes and the CEL is not popping on.

The instrument cluster is all LED lights, so not an easy bulb swap.

I don't really have experience with diagnosing a circuit board and soldering and swapping out a faulty LED.

It seems an unlikely situation that the LED would fail, so while possible, i'm looking for other things first before I just bite the bullet and buy a new cluster because of this and not even 100% sure that's what's going on.

My question: What other possible causes for the CEL not working could there be that is not related to a faulty instrument cluster circuit board?

Any ideas on things to check to rule out first?

Thanks much.

 

[importman]

I'd be willing to bet that someone removed or broke the bulb. Possibly had problems with it repeatedly coming on or staying on. I've seen people do that so it won't be on when they try to sell it or trade it in.

 

[endo1]

It is an LED, so no bulb to remove. The LED is still there...i removed the circuit board and saw it.

Like you though, i thought the seller removed the bulb, until I found out it it didn't have them.

I think 3rd gen have regular bulbs you can remove/replace for the instrument gauges but not the 4th gen 4runners.

 

[importman]

It is an LED, so no bulb to remove. The LED is still there...i removed the circuit board and saw it.

Like you though, i thought the seller removed the bulb, until I found out it it didn't have them.

I think 3rd gen have regular bulbs you can remove/replace for the instrument gauges but not the 4th gen 4runners.

I didn't realize that. But my premise still remains. If someone wanted to disable it it shouldn't be too hard to figure out which wire to clip. I worked at a salvage yard for a few years and I had a customer who was a used car dealer. He ordered a low mileage instrument cluster for just about every Chevy truck he sold. I know GM had some problems with their clusters but this was excessive. And he always insisted on low mileage; never even tried to get close to matching what was on the truck. Just saying this to show what kind of people are out there.

 

[aemravan]

do you need a functional engine light where you pass your inspection..?

For future purposes, when buying a used car never trust what you see/dont see on the dash with regards to the check engine light.

Buy a cheap OBDii blutooth adapter so plug in an check the current status yourself. Even if the light is perfectly functional, all you have to do is reset the ecu to get the light to go off until all the system are initialized again. Some cars can go 100-200 miles before the light would come back on. It took a buick I had almost 2 full tanks of gas before the ecu "initialized" and popped back up with a code that I thought I had resolved finally.

But anyhow, obviously you know that what code it is throwing, so if you resolve that issue (more than likely an 02 sensor, but depending on the mileage could also have the converters faltering at this point I guess..) would it not pass the inspection

as far as LED goes.. get out a multimeter and check the LED. Put on the continuity/led tester setting and throw your leads on the LED, if you don't know which is negative and positive try it both ways. the LED should illuminate in one of the positions. If it doesn,t the LED itself is shot. .. if you have some basic hands-on skill it really shouldn't be too terrible to swap. You'd need a fine-point soldering iron and some steady hands not to get solder on other traces around the board but it shouldn't be terrible to swap. You just have to pay attention to the orientation of the LED so ensure the polarity is still correct.

 

[endo1]

To follow up on this.

I pulled the circuit board again and it is not even the correct board for a 4th gen 4runner. It looks nothing like what it is supposed to, so no idea what vehicle it matches.

Also I can see where they clipped off a number of the LED on this board that used to be there.

So at this point, i'm going to throw it in the trash and find a replacement from somewhere.


Thanks for the feedback.
.

 

[Gigachad]

I'm a few years late to this, but how did this work out in the end? I recently bought an '04 knowing the CEL on the dash didn't work. Pretty sure one of the previous owners at some point disabled the light and also rolled back the odometer by about 125k

 

[AuSeeker]

I'm a few years late to this, but how did this work out in the end? I recently bought an '04 knowing the CEL on the dash didn't work. Pretty sure one of the previous owners at some point disabled the light and also rolled back the odometer by about 125k

You will not get an answer from the OP, looking at his profile he has been back on the forum since his last reply in this topic almost 4 1/2 years ago.

I would recommend trying some of the suggestions posted in this topic by others trying to help.