No power from the obd module on a 98 chevy cavalier

Do you have a wiring diagram for the 4X4 module ? Check power an grounds for the module first ,before you assume anything . Free wiring diagrams at http://www.bbbind.com/free-tsb/

assuming its the obd ll port od = overdrive change fuse for the cigarette lighter that is also the power line for the obd ll port the fuse box is on drivers side of dash open drivers door and on side of dash open panel page 6-61 and 6-62 of your owners manual shows which one
2001 Chevrolet Cavalier Owner Manual

Check the cigarette lighter fuse.. This is where the DLC gets power from.

Check the fuse for the injectors. If you have a test light, check for power to the injectors with key on. Pull off one injector connector to check for power. 2 wires to each injector-one is the power wire and powered anytime key is on. The other is the ground wire going into the computer, where it is internally grounded for a split second to pulse the injector-fuel is then sprayed out.
If power circuit is good, test the ground circuit: clip a test light lead to the POSITIVE POST of battery. Insert tester probe into the ground terminal of injector-the one that has no power with key on. Now have someone crank the engine over: test light should be blinking.
If both tests work-steady power to injectors with key on, and blinking tester on ground terminal with engine cranking, then the injector drive circuit and the ground circuit is working.
Let me know what you find. Good luck.

There is a fuel pressure test port on the top of the engine in the pipe that delivers fuel to the injectors. You will need to buy the special gauge that hooks to this test port. The test port looks like a large tire inflating valve and has a plastic cap on it. Autozone and others have these fuel pressure testers for about $20

could be the switch on the column or the body control module. You can troubleshoot the switch if you can find the connector C1 shown below. On the OBD, check your cigarette lighter fuse--it may power the OBD port.

I would recommend checking the fuse that controls the cigarette lighter.... i know it sounds strange, but most manufacturers link the power to the OBD test port to the same fuse as the cigarette lighter, mainly because it would be the least used accessory in the vehicle. Hope this helps.

I have the same problem. I found out that in 95 chevy used the connector for an OBD-2 system and the PCM for an OBD-1. In order to access the computer you need a scanner that fits the OBD-2 connector and reads the OBD-1 PCM. I called around and either you can take it in (if drivable mine is not) to Knechts and they will scan it for free. Auto zone carries the CP9185 accutron scanner for 250 dollars and if it does not work for some reason you can take it back as long as you don't ruine the package. Other companies make scanners that will work but they all cost 250 or more. Good luck.

OBD stands for on board diagnostics.it could either be a connector problem or a computer problem.take it to your local parts store and have them hook up a tester for free.if the computer is dead take it back to the dealer it should still be under warranty.thanks for using fixya.

Check your fuse panel for a fuse panel. You are probably not getting power to your diagnostics port on your vehicle. I do not remember which fuse the port is under but just look for the blown one.