98' F150 xlt 4x4 150k miles

My truck won't pass inspection because it keeps saying that all the tests are in "Not Ready" state.
If I drive the truck for a while, the o2 sensor and o2 heat sensor will go into "Pass" state, but the others stay in "Not Ready" state (Evap, catalyst, etc.)
Once I turn the truck off and then back on, everything resets again. CEL isn't on. Battery is 14.5 volts.

Does anyone have any ideas what is wrong? Why does the computer/ecu keep resetting?

thanks

 

There is a small fusebox tucked into the corner of the fenderwell and the firewall on the driver's side. Open it up (remove the tape if the tape is still on it).

There should be two fuses in it, a 3A or 5A closest to the front of the truck and a 15A or 20A fuse in the second position.

The first fuse is there to supply Keep-Alive Memory power in the PCM. Yours is either open, missing, or that circuit is dead. Without power on that circuit, the PCM resets after a few minutes once the truck is turned off.

That fuse box is not in the 98's owner's manual but is in the manual for the 97. Use the link in my signature to download a 97 manual for reference.

 

Thanks for the info.. it seems that was the problem. when i tried to pull the fuse out, it disintegrated and the 2 leeds were still stuck in the fuse holder. it didn't seem there was anything there to complete the circuit.
i haven't driven the truck enough yet to know if that will solve the problem, but i think it will.
thanks

 

did that solve problem my truck does the same thing

 

You never answered this question since it is the most probable fault.

 

make sure you put the same amp fuse that goes stock with the truck. the biggest mistake ive seen people do when fuses kept blowing is replace them with a larger amp fuse, then the components that the fuse was supposed to protect gets fried. and that can be expensive.

 

yes i replaced fuse mine didnt look bad thoe let me give you a little info on the truck mines a 97 it has had the motor replaced which is a 99 now hears my question i can go fill up at a gas station with my truck running the shut it off while still at the pump turn it on and my cel is on then turn the truck off for a minute or 2 and the light is off i took it to get inspected the otherday and it coms up with all 5 monitors not ready ive driven the truck thru appropriate drive cycles nothing

 

i have also taken a 300 mile trip with the truck and it never kicks the check engine light on while vehicle is running

 

There are 8 system monitors that must all complete the testing of their asigned systems.
The EVAP system takes the longest for testing depending on the condition of that system.
Normally most states will allow that system to be non complete and pass you as long as there are no other "codes set", CEL on, or other issues detected.
If just one monitor is non complete, you/they will see a code 1000.
This code is just backing up the fact that one or more monitors have not completed.
As an example, If I do a clear on a good system, it has to retest all 8 monitors even with nothing wrong, by design.
My EVAP takes long time to complete because testing has shown a phase 0 test is low on inital vacuum pull but not to the pont it will set a fault code.
This is the result of having a 'scanner' not a reader, that can look at the mode 6 live data and see the operating results.
There are really no secrets or magic about these systems any longer if someone knows how and what to look at and has the info to interpet the test results.
This system version is already obsolete as of about 2004.
Good luck.

 

MY TRUCK IS STILL HAVING THE SAME PROBLEM I TOOK IT MY MY MECHANIC HES TRIED A BUNCH OF THINGS WE REPLACED COMPUTER NO DIFFERENCE SOMETHING WEIRD THE MAF READS NEGATIVE 40 EVERYTHING STIL COMES UP AS NOT READY DOESNT MATTER HOW FAR YOU DRIVE TRUCK OR WHAT YOU DO I CAN FOLLOW DRIVE CYCLES TO A T AND IT DOESNT WORK STRANGE THING I CAN KICK THE CEL OFF BY REMOVING GAS CAP SHUTTING TRUCK OFF AND THEN RESTARTING IT THEN I SHUT TRUCK BACK OFF AND WAIT A MIN AND RESTART IT THE CEL IS GONE AND THERE IS NO RECORD OF IT ANYHEL IS APPRECIATED

 

After all that was done, you still have missing power to the PCM.
If the PCM does not have power to keep it's memory alive, it keeps rebooting each time the power is turned off and back on for the next startup.
What you see happening is what normally would be expected to happen under such conditions..
Use voltmeter to test for voltage at the fuse panel and for a good fuse in that postion.
If ok, then a test at the PCM connector pin is warrented to see if the keep alive voltage is present.
Looks don't do it, testing will.
Good luck.