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Vincent, Ford Senior Master Technician
Category: Ford
Satisfied Customers: 1450
Experience:  28 years as Tech.
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1998 ford explorer: you disable the theft key..few seconds

Customer Question

How do you disable the theft system on a 1998 ford explorer when you only have one key and no remote, I bought the vehicle this way. I put in a battery to start it and now it runs for a few seconds and then shuts off. I believe now it's the theft that is flashing that is causing this issue with the no start.
Submitted: 9 years ago.
Category: Ford
Expert:  Vincent replied 9 years ago.

If the theft light is flashing that is why your truck is not running, it thinks that it is getting stolen.

The problem is the system cannot be bypassed or disabled. It is built into too many systems and there is no way to remove it from all the computers. This is expecially true as all the Explorers have the system (as do most Fords) and there is no parts to change them to that don't have it.

Did the vehicle run with the one key at one time?

Customer: replied 9 years ago.
Yes the vehicle ran with that key, when we first when to pick up the Explorer , I put in a battery it started and ran fine, I pulled out of the drive way and it shut off about 25 ft down the road, I had it towed to my house and this is where is has been for the last two weeks, I replaced the fuel pump, fuel filter and IAC motor and it still starts and shuts off, I have read that the theft system will let the car run with whats in the line from the fuel pump and shuts down the fuel pump after start up. Is there a way I can reprogram the key to work again or do I need to get a new one programed?
Expert:  Vincent replied 9 years ago.
I want you to try something first. Tilt the steering wheel and retry the key. I think that you have a bad transponder (the sensor around the key) and that is what is causing your problems. The transponder fails because a wire breaks going down the steering column. Sometimes tilting the column into a different position corrects the problem, temporarily.
Customer: replied 9 years ago.
Ok I tried that and it still doesn't work, now in the manuel it says, Disarming the system , Unlock the doors with a key , turn the key full travel to the front of the vehicle to make sure the alarm disarms, Unlock the doors by using your keyless entry keypad, or turn ignition to ACC or ON, it also states that the theft light should flash three times and go out on start up, if there is a problem with the system the light will contine to flash or it will glow bright, so since it goes out on start up and don't flash or glow, wouldn't that rule out the security system?
Expert:  Vincent replied 9 years ago.

If the theft light is flashing continuesly, then the vehicle is disabled.

If the theft light goes out when you are cranking over the engine, then yes the theft system is NOT the problem. On your vehicle, I would be looking at the fuel pressure. And yes I know that you have replaced the pump, but that is where I would start. I have put in more then one bad pump in my life time.

Also check the Interia switch, and make sure that it is not tripped or unplugged. It is located on the fire wall, dead center, in the passenger side foot well at the top of the carpet. I have seen them get unplugged by the passangers feet.

Customer: replied 9 years ago.
Reply to Vincent's Post: The theft light is out when I'm cranking the engine. As for the fuel pump, when you turn the key on, you can hear it kick on, we have pressure at the release on top of the motor, but once the engine stops, the pressure is no exsistant.
Customer: replied 9 years ago.
Interia switch is not tripped and is still pluged in
Expert:  Vincent replied 9 years ago.
We need to know what the actual pressure is. You may think that you have enough when you depress the schrader valve (the fuel pressure test port) but it is probably not enough to run the engine. You want at least 30 psi at the rail, less then that and the engine will not run properly.
Customer: replied 9 years ago.
We checked the pressure at the schrader valve at 40 psi, while cranking the motor over, once it started it ran for a few seconds and shut off, when it shut off the psi was nonexsistant. With the motor not running.
Expert:  Vincent replied 9 years ago.

Your fuel pump is shutting off. You need to locate the fuel pump relay and using a jumper wire, jump to two large pins. The relay is a small one on this truck and on the bottom there are either two or three small pins and two large pins, you will want to take a jumper wire and go from one parge pin to the other. You are basically doing the job of the relay. Then retry the vehicle.

Here is a picture of the fuse box:


Customer: replied 9 years ago.
Reply to Vincent's Post: Ok I jumped out the fuel pump relay and I could hear the fuel pump run continuesly, I tried starting the vehicle and it runs for a few seconds and shuts back off.
Expert:  Vincent replied 9 years ago.
And the fuel pressure when it quits running is?
Customer: replied 9 years ago.
the pressure is pretty much nonexistant when the motor shuts off, with out haveing the fuel pump jumped out. Not sure what it is when the fuel pump is jumped out.
Expert:  Vincent replied 9 years ago.
Then you have a bad fuel pump. Test it with the relay jumped and watch the fuel pressure. If it drops below 30 psi the pump is no good.
Customer: replied 9 years ago.
Reply to Vincent's Post: Ok, I tested it with the fuel pump jumped out and it stayed between 30 and 32 psi, but as soon as I remove the jumper from the relay, the fuel pressure goes to pretty much 0.
Expert:  Vincent replied 9 years ago.

The check valve in the fuel pump is bad. The problem is the only way that you can replace the check valve is with the fuel pump. The check valve is designed to retain pressure inside the line so that the vehicle will fire up quickly (on the first key cycle).

However it looks like you also have a bad fuel pump relay. With you jumping the relay and the pump turning on that tells me that the pump is working but that the contacts inside the relay are carboned up. This normally happens when the fuel pump starts to draw more current then the relay was designed to handle. That is also a sign that the fuel pump is bad as well (excessive current draw)

Customer: replied 9 years ago.
Ok, I have a new fuel pump comming on Tues, after I put it in I'll let you know the out come.
Expert:  Vincent replied 9 years ago.
Don't forget the relay! And I am looking forward to the results.