I have a 2000 f-150 4 x 4 supercab with a 5.4. never had a problem till now. the theft light stays on all the time. i tried disconnecting the neg. battery terminal. this worked for a couple of starts then it was back on. i'm looking for the quick easy fix and hopefully not the costly one. thx.

 

Have you tried a spare key in the ignition?

 

please someone help. i haven't figured it out yet

 

the truck starts and runs fine. the light just stays on.

 

I've never seen your problem but the manual says that if the light goes on and wont shut off it needs a new instrument cluster.
Maybe someone else has seen this before.

 

The only thing similar I have seen was a shorted wire to the processor to the SCP BUSS, but it was intermittent. I think your best bet is to let the dealer look at it. If the cluster needs replaced they will need to do it anyway. The F series with its Hybrid Electronic Cluster (HEC) can be a tricky one to diagnose.

 

I may know a little more on this soon. My wifes Taurus is doing something similar she informed me this morning. She said her theft light flashes with car started and running and does so for a couple miles. So I will be checking it out in the next couple days. With any luck it may be related to a similar problem, although I dont believe the Taurus has a HEC cluster. Ill be taking it to the dealership since she has extended warranty. Ill probably be taking it in Saturday since she has to have it for work today. I wont be working Saturday so Ill see if anyone can fix it without me holding thier hand... LMAO!

 

Well in my case it was an easy fix and I was able to work on it myself this afternoon at the shop. The PATS module had a code in it for SCP buss invalid data, and the processor showed no theft codes. This meant that the processor was failing to power up at the same time that the ignition switch was turned on and thus the PATS system detected a problem and flashed the antitheft lamp. It would however active correctly within enough time to enable the processor to recieve the PATS Transciever ID of the key and allow the vehicle to start and drive, despite the flashing Theft light. At times the timing was too late however and there would be a no crank condition. There never was a code in the processor however for wrong key code or failed Pats.

I corrected this by simply replacing the PCM power relay in the power distribution box, which was sticking. Hope your problem ends up being this simple to fix.

 

The reason for coming here was to get an idea why my theft light was staying on after starting. First I believe it was because I haven't started my truck in over a week. The battery might of got low. Well I went to start and it just cranked over. I tried again and it started, but this time my theft light stayed on. So I just let the truck run for a little while when I was cleaning the windows. Then I looked up and it was off. I then went for a drive because I haven't been driving it. Need to charge up the battery. Someone said in their post that the PATs might have low voltage or something. I don't know. I just think I need to drive it more often to keep the battery voltage up.

 

Hey guys!

Had this issue on my 1999 Mustang (I know, not an F-150 but close enough)

First, check the battery and make sure the voltage is good and the terminals are clean
Then, check the battery in your key fob.

If it's not either of those things, chances are you have a bad Key Transceiver. Not sure of the part number for your truck, but the transceiver is basically a little plastic sensor that goes around the ignition cylinder.
Sometimes the theft light stays on when the transceiver doesn't read the key.

It may also be the key itself that has gone bad...

Also note, if you replace the transceiver you are gonna have to reprogram the keys to your car

 

I just fixed my "always on" theft light today in my 1999 F-150. I took the cluster out, and started looking for cracked solder joints. I had problems with the odometer solder joints in the past. Nothing obvious. I then assumed that the solder joints at the connector plugs on the board were faulty. I desoldered the connectors, then resoldered with leaded solder. I then compressed air blew the board. Reinstalled, and the theft light now works normally.