Hey guys,

I have an 87 xj and when i engage the 4 wheel drive the emission light turns on then when I get it out of 4 wheel drive and drive for a bit it turns off. Is this normal? I am not getting the check engine light, just the emissions light, am I missing something? Please help I can't figure it out

 

why it comes on when you put it in 4wheel drive is more than likley the bulb is in the wrong slot on the back. There is no check engine light on an 87, The emisions light is actually just a counter,it tells you to change your 02 sensor,it goes off at around 82,000 and it has to be changed when the sensor is replaced. I doubt many have been sold

 

So this is somehwat normal then? if I switch the bulbs and replace the O2 sensor everything should be fine?

 

No what I tried to say is,check and see if the board these bulbs are in could have slipped,or someone has replaced the bulb and accidently put it back wrong,I think it is doing what it is suppose to do,just in wrong place.
As far as the 02 sensors goes,there is a timer under the dash,it counts miles,it will iluminate the emisions light at 82,500 miles,it cannot be reset,it has to be replaced,it is just a reminder,nothing else,do not replace sensor unless it goes bad. I hope that is better.

 

putting the bulb in the wrong slot wont change anything. the bulbs are all the same. If i put my 4wd bulb in my check engine socket the check engine light wont come on when i put it in 4wd.

Most likely wiring is getting pinched in the Tcase linkage causing this.

 

Check your wires,somehow you have to be putting power to the emisions wiring to iluminate that bulb,or the card the bulbs sit in is shorted.