2.3L ('02-'11) 2003 Ranger losing power and trying to stall while driving, "THEFT" light coming on.

[King Of Mercia]

I love my little 2003 Ranger!

Yesterday it started having a problem that was really unpleasant.
Accelerating from a stop, it lost power but didn't totally die, intermittently jerking and trying to stall.
While this happened I noticed the "THEFT" light stayed illuminated for a moment. I found similar problems described elsewhere online, but no real solutions. Here's one from Taurus Club that sounded similar.

"hey i have a question about my ford taurus 2005 SEL... I left my key inside my car. however the engine was OFF but the radio was ON. After 8 hour i realized and try to open but the battery was dead. I called lock smith and got my key out. I jump start the car and while i was driving it jerked and theft light turned ON. RPM drops and after 3 second the car was normal. again i stop on a trafic light and after the light turned green i press my gas padel and the again it jerks RPM droped and theft light flashes and after 2-3 sec theft light was OFF i dont know whats goin on..?? the car was just running fine before then. i had it for five yrs now. Please help.. i have no idea about cars.. "

I swapped the battery with a new one, but the problem persisted. It would sputter, lose power, try to stall, and come back all herky jerky while moving. Especially when changing gears, though it also happened just cruising too.
I've scoured the internet and think maybe it's a grounding problem or a PCM problem, but I'm really not sure. Anyone familiar with this kind of issue?

Truck starts fine and idles nicely. Most online questions were about PATS and flashing theft lights, which isn't what I'm experiencing. PATS shouldn't kill a moving vehicle anyway.

Oh, and when I got home it didn't throw any codes. I think that about covers it.

Thanks so much for your help.

 

[King Of Mercia]

bump, any ideas?

 

[King Of Mercia]

Got a video of the problem.

 

[superj]

welcome to the group!

i have no experience with anything like what you are going through but have you made sure the battery connections were nice and clean inside the cable end that clamps to the battery?

maybe also make sure all the grounds from the engine to the frame and to the battery are solid still? it does sound like a loose wire somewhere

 

[King Of Mercia]

I'll check the battery connections. What should I be looking for? The clamps are the bolt-on type, they bolt to the wires. They're a little ratty. Any suggestions for a better quality replacement?

I'm not sure where all the grounds are. I have found three in the upper part of the engine bay so far.

• Bottom one is battery to engine bay.
• Top one is supposed to be block to cab. Cab side is tight.
• Not sure about the right hand one.
• I think there should be an block-to-frame one somewhere? Cant' find it.

(I know it's the 3.0 diagram but I'm just trying to show where I found them.)

Finally, my buddy noticed some kind of rattling "clank/clunk" sound coming from under the cab on the driver's side. Couldn't figure out what it was or if it was related, but it's a new sound. I had thought it was the slip yoke splines but those are in a different spot. I think all the suspension parts looked tight. If I can't get it sorted out soon it's going to the shop and I can have them check too.

Thanks for the welcome! Love these little trucks.

 

[fixizin]

ZERO experience with that 4-cyl engine, BUT... doubt it would be the battery cables since in your video the starter turns over strongly, AND... even a dead/disconnected battery wouldn't kill a running engine. So leave that new terminals/cables task for later.

When my 3.0 6-cyl had that problem--twice over the 24 years--once it was the IAC (tried cleaning, ended up replacing), and more recently it was the MAF (forget if it threw codes, replaced it too), both are easy to get to. Cleaning the filament w/ MAF Cleaner might be enough, but prob. have to replace it. MAF can be tested with a voltmeter, IIRC there's a thread or Lib Article on here that tells how.

 

[King Of Mercia]

Sick, thanks for the heads up. It's at a electrical specialist shop now that's good a good reputation. I'll let you know what turns up from it.

 

[bhgl]

A couple things id recommend overall when the safety systems are acting weird is to verify 1. it hasn't been crashed and put back together, 2. that all the modules are the right year. 2001-2003.5 year rangers are in a weird spot and have specific modules that dont all work with most every year.

 

[King Of Mercia]

UPDATE:
Problem solved.

To everyone at Ranger-Forums for the awesome advice.

I have read that the Crank Position Sensor is the only one that can cause a moving vehicle to die like that. Not sure of the veracity of the statement but there you go.

In my case, the Crank Position Sensor was ok, but a wire in the loom connecting it was shorting to ground on the frame and killing the truck.
At some point in the past, someone doing work put the wires back in the wrong spot and they slowly wore through. The action of shifting would jostle the cable just enough to tap the frame and short the circuit.

Glad to be moving again.