Alrighty then. New to the forum, but frequent reader. My problems have gotten me to the point of having to ask some help.

2003 Ranger 4x4 4.0L having stalling and no start problems. The CEL, THEFT and Check Fuel Cap lights flicker/flash (no regular pattern) when its having its episodes. I can feel and hear the PCM Relay clicking and the Idle Air Control Valve clicking erratically during the epsiodes as well.
-Inertia switch bypassed
-New crank shaft position sensor
-New Coil pack, plugs, wires
-Recent tune up with filters changed
-Every ground I can touch removed, cleaned, tightened
-New battery
-Fuel pump is fine
-No codes
-Emmisions tests are good, all sensors/systems OK
When I unplug the battery OR the EEC-V, I can drive it for a few miles, or until I am assuming all BIT checks are complete. Then all my problems happen again.

I'm leaning towards a bad EEC-V, any thoughts?

 

Welcome to the forum

PCM = EEC-V

It reads like engine system is losing power, PCM relay "clicking"
PCM relay is closed when key is turned on, it powers PCM, and IAC Valve, plus most sensors and engine systems.

PCM Relay isn't controlled by PCM, it is a simple power on/off by ignition key relay, so if PCM Relay is "clicking" then it is bad or it is losing 12v or ground

So could be ignition switch under steering column is the problem or it's wiring.

If power is cut to PCM(PCM Relay opens/closes) then PCM Resets and CEL, Theft and other dash light will come on for a few seconds on PCM re-start

You could pull out the PCM relay and test its base/slots to see if it has good ground and then stable power with key on
There are 4 active "slots"
Ground is full time, not controlled
Then a key on/off 12v from ignition switch, jiggle key and wires when testing this one

It will also have a full time 12v from PCM Fuse/battery
4th slot is 12v OUT to: PCM, fuel injectors, coil, IAC Valve, fuel pump Relay(not fuel pump), ect..............it powers most engine systems


It is possible the PCM is failing, but PCM relay wouldn't be clicking, and you usually wouldn't get dash lights, you would get running issues with no codes, or get codes with no issues

 

I put a multimeter to the truck and it is hard to get it to behave misbehaving. Voltage at the Central Junction Box 25A Fuse A068 doesnt change drastically with an episode. A difference of .2VDC with the clicking of the relays and IAC. I changed the PCM Diode with a known good one and the PCM Relay 1x1" Black block with a new one I had sitting around. Still acts up. Power to the Battery Junction Box is normal as well. It is hard to predict a freak out, so being under the hood at the BJB with the PCM relay pulled is hard because I don't have any visual or audio clues to and episode. The wires and connectors appear normal. I will try to clean the BJB connections as best I can and recheck.

 

A 12volt test light might be helpful, you could see the light dim or go off if voltage is being lost

 

Used a voltage light to test the pcm relay, diode, and fuse. Checked in the CJB as well. Checked everything i could think of again with multimeter and light, when appropriate. No dice.

Got it running by the usual unplug EEC I have been doing. This time did some more wire wiggling. Tapped the coil pack and it stalled, normal clicking issues at fuel solenoid, IAC and PCM relay. It stopped, I fired it up. Tapped again, nothing. Wiggled the bundle that runs under and behind up to the EEC, stalls. Fire it up, wiggle again. Immediately stalls. Do it a third time, stalls. I open up the bundle to check condition of the wires and wiggle more. Truck freaks out and now the theft light blinks rapidly, just as if you were to trigger it. No horn or lights, just THEFT blinking rapidly. Now i can't get the damn thing to stop that.

After a while ALL relays stopped clicking, even the fuel relay. Now i unplugged the battery and switched relays around, now the fuel one clicks and the pump primes but the THEFT light stills blinks. Swapped relays back and now the relay clicks and the pump primes.

I am so confused.

 

In 2003 the THEFT light is the PATS(passive anti-theft system)

PATS is in the PCM, if theft light is flashing rapidly it means the key in the ignition was not recognized by the PCM/PATS
This disables starter motor(on most models) and fuel system

PATS is only used when key is first turned on, once key is recognized then PATS is off-line until key is turned off, or PCM is turned off and on.
So unless PCM is being powered off while driving PATS can't cause a stall.

Inside each PATS key's handle is an embedded RFID tag, it has a unique number.
When you turn the key on an antenna(loop/wand) around the key slot reads this RFID tag number, the PCM/PATS has a list of 3 or 4 numbers programmed in at the factory of the keys for your truck, if it reads a matching number then PCM will allow engine to start.
If its a wrong number or no number then THEFT light flashes rapidly and no start

New PATS keys can be added to the PCM/PATS memory, you can do it IF(big if) you currently have TWO working PATS keys, if not then a Locksmith with Ford software can add new keys.
Or a locksmith can "clone" a working PATS key so you have a spare key, this doesn't count as TWO working keys since as far as the PATS system is concerned they are ONE key because they have the same RFID tag number.