Hey folks. Ive got a 2002 plain jane tracker with 60,000+ miles on it (4cyl 16 valve). Recently Ive been having the following issues:

-"Service Engine Soon" light is on even after oil change.

-While driving at night my gauge lights, head lights and high beams will pulsate. Now they wont go out or anything like that, they rather get brighter, or more dim. Its not a constant pulse either.

-And finally I bought and drove my tracker in AK where the winters drop to -45. It would heat up normally and stay warm. The temp gauge would be at half at all times. Now I moved to Idaho, at night/morning when it gets cold, the heater will be blowing warm, and the gauge will register half. But after 30+ minutes of drving on the highway the gauge will barely register around a 1/4.<img src="/forums/images/graemlins/confused.gif" alt="" />

Im trying to avoid taking it in for a code reading test, since they want to charge an arm and a leg for it. Does anybody out there have an idea of what Im dealing with?? Thank you in advance.

Maybe your intake air temp sensor which plugs into the air box is broken? If the wires are broken, or the sensor goes faulty, the ecu will always think it's around -40'C. It would cause your engine to run a little rich, also would throw a code.

If you could borrow a code reader from someone, or take it to a private mechanic who doesn't charge too much for it, then you'd know for sure what the issue is.

The pulsating lights seems like an electrical problem, either a bad alternator or a bad chassis ground.

Bad alternator or lose alternator belt. Mine did the same thing and it was the electronic control inside the alternator, the one that controls the voltage level.

Clean the battery terminals and look for corrosion on other connections such as ground. Also, test the battery and test the electrical system.

The thermostat may be stuck partially open.

Since the Check Engine light is not on, you probably won't have any codes. Some auto parts stores will read the codes at no charge. AutoZone does this where I am.