Need Help - 5 bad codes. Could it be just bad computer?
 

I have a 1999 Ford Ranger 2.5L 2WD. The check engine light is on and displaying 5 codes when I scan it. P1506 (IAC overspeed error), P0135 (O2 bank 1 sensor 1), P1451 (Evap), P0141 (O2 bank 1 sensor 1), P1451 (Evap), P0141 (O2 bank 1 sensor 2), and P1409 (EGR Vac). I need to know how to approach fixing it. While the truck is running, I unplug all the sensors and the truck continues to run. No change in idling whatsoever. Am I looking at a defective PCM? If so, how difficult is it to replace. I can get the new computer cheap but need to change it myself. Thanks.

I found that the PCM is on passenger side, behind kick plate along door. Is that correct? How difficult is it to replace? I've had my Ranger for 10 years with 176,000 miles. I'm not ready to send it to the graveyard yet. Please Help!

It wont pass inspection in NYS until I get the codes cleared and fixed.

Disconnect your battery ground, turn on the headlights for a 15-30min period. Reconnect and see what happens.

I'm trying it right now. Not sure how it will do anything but I will try anything to get it to work right. Thanks. Will let you know what happens.

Yea, clear the memory (by doing above) and the codes should clear. let us know what comes back on.

No changes. Same codes. And Ive been searching for vacuum leaks but not finding any. I cleared the codes with a scanner too and they come back on when I start the truck. It drives me nuts because the truck is running better than it has in years even with all the codes. When its running I can disconnect the tps, iac, egr, and other sensors and the truck keeps running with no change to the idling. Only sensor that it shuts off for is if I unplug the maf.

Check fuse 13 in the battery junction box under hood with a test light or voltmeter. Ensure you have power on both sides of this fuse.

I found a blown 15 amp fuse in the junction box. Changed it and cleared the codes with a scanner. Right now the light is off. I am driving it for about 30 miles then I will scan again and see what current or pending codes come up. If all the monitors show up good too I should be able to inspect it. Hopefully the 50cent fuse saves me from having to spend 120 on a pcm.

That’s fuse 13 (15amp). It provides power to the HO2 Sensors, EGRVR, EVRS , CPS, & CVS (Ref owners manual pg 139 Click Link)

Keep your eye on this fuse. If it blows again, you more than likely have a short to ground in one of the effected sensors/solenoids or associated wiring. To start, I'd check the O2 sensor wiring harnesses and any others near exhaust components.