Hi all, I’ve got a 2003 4.0 that I bought used about 2 years ago. It came with one key and one fob. When I unlock the doors with the fob, I can hop right in and start it up no trouble. When I unlock the driver door with the key, as soon as I open the door I get a bunch of clicking from behind the dash and the and the little red light down below the center console flashes rapidly. If I then unlock with the fob, whatever anti theft mode that was activated goes away and I can start up OK… the other day, however, the fob unlocked the door but no start, no crank, no clicks. I swapped the battery out in the fob and disconnected/reconnected the battery under the hood and was able to get going again. No issues with the fob since, but I’d like to get some extra keys and fobs so I’m not completely dependent on this one 20 year old fob to keep working.

I replaced the battery and terminal clamps a little while back, cleaned the terminals etc. I get 12.6V after letting it sit overnight and 14.4V in idle so all seems OK there. No noticeably blown fuses. Power door lock buttons work just fine.

Because I can start up at all I gather that this isn’t a PATS issue… but because 2003 seems to be something of an in between year for rangers I’m not even totally sure that this ranger is equipped with PATS. I removed the passenger side airbag and confirmed the existence of a beige “Remote keyless/ Anti theft” box.

Question #1: would that beige box be PATS or the CSM? Or is PATS just a component of the CSM?

Question B: I don’t see a RAP module anywhere behind the drivers seat (but I also didn’t fully pull out all the paneling to check). Should I even expect one to exist?

Question iii: Since unlocking at the door with the key triggers some sort of anti theft mode, can anyone describe how the door disarm circuit works with a key? My thinking was that somehow the key is lifting the lock mechanism but otherwise failing to complete a ground making it seem to the electronics like the door has been opened while still “locked”. I was just trying to pull the actuator out to see how it all fits together, but the bolts holding the actuator to the door won’t budge even after penetrating lube and a hammer drill… go figure.

I’ve read through many of the anti theft related posts on here, so apologies if I simply missed the answer elsewhere…. Hoping Ron can help! Thanks in advance for any help!

Bonus question: When I go to unlock at the drivers door with the key, I can only unlock the drivers door. I would normally expect the passenger door to unlock if I turned the key twice in quick succession. Up to now I’ve assumed that the this truck just doesn’t have a feature like that, but maybe it’s related to the other issues?

 

RAP module was replaced with the CSM, so its one or the other, in 2003 its a CSM
PATS is in the engine computer in 2003, so no separate module

I didn't think there was a key unlock switch on the drivers door in 2003 but maybe there is, but I would also expect horn to honk and lights to flash(exterior) if there was
Like an alarm system if door is opened without the key

The RAP module could have that, so maybe the CSM as well
There was a switch in Driver side AND passenger side door that would be OPEN until door was unlocked with a key or with a Fob, then it would be GROUNDED, so if CSM sees that switch grounded then no alarm, which means you could jumper the 2 wires on the switch together so CSM never sees that the door is locked
This is not the Door Open sensor, its a different switch inside the door, on the latch mechanism
Check if the passenger door key works to disarm the alarm, making it a driver's door specific issue not a CSM issue


Fobs are easy to add to the CSM, just get the new Fobs and have all the fobs in the vehicle with you
Doors closed
Cycle key on and off 8 times in under 10 seconds ending with key ON
Door locks should cycle once, this means ALL Fobs were just erased, so if an EX had a fob or you lost one it would no longer work
Then push either the lock or unlock button one time on a fob
Locks with cycle if it was "learned"
Then do next Fob, and next
Turn ignition off when done
Test each Fob

Adding PATS keys is not so easy
A locksmith can cut PATS keys and then come out to the vehicle with a laptop and add them to PATS in the computer
Forscan is a software that can do this as well, but you need a laptop and an OBD2 to USB cable

Locksmith can CLONE your current working key
Each PATS key has an RFID chip in its handle, it has a 40 or 80 bit unique number, thats what the transceiver and PATS reads with key on, if that number is in PATS memory then "OK to start" if its not then "no start"
You can get PATS keys with a Blank RFID tag
So locksmith cuts the key to match working key for the lock part, then READS the working keys number, same as PATS does, the WRITES that number to the blank RFID tag in the new PATS key
So less expensive method
No real downside in a CLONE key that I have ever seen

When testing new PATS keys only have one key in your hand, 2 PATS keys close to ignition switch will cause an issue in "reading" just the one key

 

Hey Ron, thanks for the response! I should’ve mentioned in the first post that unlocking with a key at either driver OR passenger door causes the issue. The only way to get the engine to crank is to unlock with the fob.

I get a door ajar light with either door open so those sensors appear to be working fine.

I’ve been using a wiring diagram you posted a while ago (attached again here). Since opening either door with a key induces no start, I guess I should try to follow the lengths of lines 119 and 120 leading to CSM pins 9 and 17 to look for any kind of break?… electrical is not my strong suit.

Does the fob talk directly to the CSM? I would have thought that unlocking via the fob would talk to the CSM via the same route as the door locks, but seems like maybe it talks to the CSM directly considering it appears to bypass the disarm by key process.

A dumb question, but just to confirm—PATS only comes into play when the key is in the ignition right? There’s no handshake with PATS when unlocking doors?

Good point about the fobs… I’ll order one now to program while I try to figure the rest out.

 

My clones have batteries in them. Ilco says the batteries should last 5 years, so I'm preemptively replacing them every 3.

 

No. PATS is strictly a key reader on the ignition key slot, it disables starter motor, fuel pump and injectors if activated, and just a flashing THEFT light if its activated

The Fobs "talk" directly to CSM, CSM then activates the door locks, as directed, lock or unlock, no door switch involved

If both doors do the same thing then I would suspect a CSM issue
But from what I have read you can just swap these out and add your fobs to the "new" one once its installed, no programming

Like that 2003 diagram shows, no door lock/unlock switches connected to CSM, so maybe there is a different version CSM with Alarm system added, plenty of unused connections on the CSM, but never read about that

On generic CSM documents I do see this listed as a function "perimeter anti-theft system" which is an Alarm function, not related to PATS(passive anti-theft system)

 

Are circuits 119 and 120 not door lock switches?

And then circuits 117, 118, and 163 between the actuators and CSM also lead to door lock/unlock functions.

Are 119/120 the power door buttons that then send signal to the CSM which in turn controls the actuators via circuits 117/118? In which case what is 163 doing…?

sorry for the many questions and many thanks for all those you’ve already answered!

 

Also when I had pulled the CSM out the only wires connected matched those in the diagram, so nothing extra seems to have been added.

 

The door actuators move the Lock/Unlock rod up and down, when one wire is 12v and the other wire is a ground it Locks the door, if that's reversed, Ground and 12volt then it unLocks the door

117 and 163 are the two wires that reverse polarity to either Lock or unLock the doors, Fob only unLocks Drivers door
118 allows passenger door to unLock separately using the Fob, 2nd unLock button press

119 and 120 are "signals" from a door switch to either Lock or Unlock, and will do both doors at the same time, CSM sees which wire is grounded, and activates both actuators to Lock(120) or unLock(119)

Part number on the CSM should start with 3L5, 2003 Ranger