Hi everybody

This is my first thread in this forum, here my dilemma

I own a Ford Ranger XLT 2.3 L Manual 5 speed, assembled in Argentina, I currently live in Venezuela, the problem I'm experiencing is that the anti theft light on the dash gets on when I drive on holes or bumps, remains on for aprox. 3 seconds during that time the engine is immobilized has no power or response, but immediately after the light goes off, is back to normal again, until i hit a hole again.

I have taken the pick up to a local dealer and after checking, they informed that is caused by a short circuit wire, but they want to charge me a ton of money for it.

Anybody has had this problem or similar, where should I look or what to check first, your help is highly appreciated.

Thank you in advance.

 

Welcome

What year Ranger is it?

And what alarm system?
Is it Ford PATS?
Dealer installed?
or 3rd party install?

Yes, dealer answered with pretty obvious answer from your description, "a short", duh

And yes, the time it takes to track down a short can be extensive which is why the big $$ are quoted, it could take them 20 minutes or 8 hours.

This is why knowing what alarm system you have would be very helpful.
You can then get the installation instructions and look at each connection yourself.

Also do you know what triggers(turns on) the alarm light normally?
like open door?
wrong key?
open hood?

This could help you narrow down where to look

 

Hi RonD

Thank you for your reply, here my comments

The model is 2007

I have a 3rd party alarm installed, i got it like a year ago. I also have the installation manual at home.

The alarm as far as I have noticed, can be triggered by shock or impact sensor, open door..

Thank you and if you need further info, just let me know i will write asap.

 

Alarm should be disabled when key is on, or do you have to disarm it with Key Fob button?


3rd party alarm may have a tip sensor, in case thief tries to tow vehicle away, it sets off alarm at certain angle, but that should be disabled if key is on, worth a look.

Not sure where it is, manual should say, if it has one and where.

2007 has the Ford "bad idea" door open sensors, these are a come issue for "door ajar" light staying on and dome light.

Usually some WD40 or silicone lube in the door latch will help them.
It is in the latch part no long a push button in the door jam.

These should also be disabled when key is on.

Could be time to bring out the big guns..............with engine idling start moving wires around, engine should stall if you move a wire that is shorting alarm trigger, also tap on the alarm control box, could be an internal short.


Last resort, disable alarm and buy a BIG dog to sit in it, just kidding.

 

Aftermarket alarm shouldn't affect it most shops will not use the starter kill on vehicles equipped with chipped keys i.e. PATS the computer routinely pulses the circuit to check the sensor in the key. If for whatever reason they did wire the aftermarket starter kill that could be the source of your issue because its a cheap relay that they use and bumps can cause it to open and then the PCM no longer has a path to the key. I had the same issue when best buy did my remote start and they had to take the aftermarket starter kill out to solve the issue may not be your exact issue but its a good place to start looking.

 

OK guys, thank you for your posts

Here what i did, I tested the 3rd party alarm, I intentionally armed it with myself inside and started up the car and it cranked on, but of course the alarm was triggered and alarm sounding which means is not connected to the starter kill, I also disconnected the 3rd alarm system and still got the dash anti theft light on. I checked the doors sensors and they worked ok.

Please let me know if there is something i can do for you to help me with this issue.

 

Is the dashboard "anti-theft" light connected to 3rd party alarm system?

Or is it just used for the Ford PATS(passive anti-theft system)?


The PATS system has a receiver/transmitter on the steering column near the Key switch.
It is connected by a wire to the Computer.
This is the wire 'pearlkid' is referring to in above post.

If the "anti-theft" light on dash is not part of the 3rd part alarm system then he would be correct, either the connection on that wire is loose or if 3rd party alarm tapped into this wire then their tap/relay is the problem.
If 3rd party alarm box is near computer then that is the most likely place to find the tap

 

Thanks RonD

Got your point, let me check that wire and see if is loose or if the 3rd alarm is connected to it. will get back with results.

 

If starting the car triggered the aftermarket alarm its getting a feed from somewhere its either somewhere inline of the starter or its reading alternator output those are the two common methods. If you pull the steering column surround off (3 screws on the bottom) there is a halo wire around the lock cylinder and that is the sensor check for any wires that may have rubbed through could cause a short there as well and get weird signals.

 

Here more feed ups.

I removed the steering lower cover and checked pats connector and wires with the engine running and moved all wires and nothing happened I also checked the wires and connections under the steering column where the 3rd party alarm is, moved wires tapped on alarm box, and nothing 3rd party alarm only has shock sensor indicator light and door lock control and is connected to the big white connection on the left side of column, i also opened the hood with engine running and moved wires and connection and again same result nothing, also tapped on the fuse box. So the theft light is still a mystery, I recorded a video for better reference with the car going over bumpy roads. I also got a on board diagnostic with FORscan and even though the light went on a couple of times, no DTC codes were detected only this code was shown by the scanner Code: P0171 - System Too Lean Bank 1

Module: Powertrain Control Module

I will appreciate your attention and help you can provide.

 

Not sure, but the PCM(ECM/EEC) on your 2007 might have its connection in the engine compartment on the firewall, on later years they covered this connector with a cover box because water would get in.
With battery disconnected, it might be worth pulling off this connector to see if water has corroded any connections inside.

Also in the engine fuse box is the PCM(ECM/EEC) relay, when key is turned on this relay closes and PCM gets power(also fuel injectors), it could be that this relay is popping open on a hard bump, this would cut power to PCM and fuel injectors.
PATS system has separate power, 24/7 since it is an alarm, so PATS light could flash when PCM loses power, because of no communications.

 

Hi guys,

thank you for your kind attention and dedicated support, as of today, I think i might have found the source of the issue, even though late last night i spent a lot of time after leaving my work, the problem possibly was a vacuum leaking hose, the one located at the back of the intake manifold, is a black hose about 1/2 inch diameter and like 4" long connected to a plastic pipe, following the on board diagnostic error code : P0171 - System Too Lean Bank 1 , i could notice an whistling sound, i moved that hose and the engine stalled, the hose was leaking and obstructed, i replaced it and everything is working normal so far, hopefully that was it. I will let you know the progress.

Thank you for all.

 

That is probably the PCV valve hose, that hose often wears thru on later model rangers or cracks at the elbow.

 

That actually makes perfect sense when the engine stalls it goes into start mode as if you just turned the key to run that few second pause is the PCM checking the key code as soon as it decides its ok then it will allow it to restart. Hopefully that solves your issue and now it makes me want to go ahead and replace my PCV elbow its been cracking from dry rot for a while and I've been putting it off. Thanks for the info on the solution!

 

Really??
From description, the bumps started the anti-theft light flashing which then stalled the engine.
I can see the bumps causing a temporary larger vacuum leak.
If engine stalled first from bumps, engine's crank would have to come to a complete stop, no input from crank sensor, before there would be any action from PATS, and even then I don't see that happening.
I am sure many have run out of gas or had other stall conditions and I have never read about that triggering the PATS.

I just can't get my head around the PATS being triggered by the engine stalling, the other way around yes.

 

its not actually being triggered at least thats what i got from his post. Although the stalling could put it in limp mode while it checks the sensors to make sure its not a major fault causing the stall and the theft light is just a side affect of the stall when i stall mine letting the clutch out to far on occasion i get a couple second delay before it restarts idk if its related or not. i may be reading to deeply into the symptoms though.