cant lock my truck
01-10-2009, 12:58 PM
#1
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cant lock my truck
Just bought a 00' super cab yesterday , got a good deal 
however the door lock actuators need to be replaced on both sides. Read a thread about a cheap foil fix, thought I'd give that a try since the local auto parts cant get the driver side till the 19th. In the meantime , I thought I'd be able to use the key to lock and unlock the door , but when I try and turn the key it wont budge.. on both sides. The interior door handle works the locks just fine when manually locked . Is this typical of a bad actuator?
Thanks , sorry for the double post
however the door lock actuators need to be replaced on both sides. Read a thread about a cheap foil fix, thought I'd give that a try since the local auto parts cant get the driver side till the 19th. In the meantime , I thought I'd be able to use the key to lock and unlock the door , but when I try and turn the key it wont budge.. on both sides. The interior door handle works the locks just fine when manually locked . Is this typical of a bad actuator? Thanks , sorry for the double post
01-10-2009, 03:28 PM
#2
OVERTHINKER
Read this for a better understanding on how the system works:
(The following applies to a 2000 F150 XLT with remote keyless entry)
1. Door lock circuit consists of
a) door switches that are grounded when closed for either lock or unlock. (Different circuit in each case is grounded.)
b) three relays that send voltage & current to door actuators. One relay is dedicate to the driver door unlock function when RAP is included. The other relays control both doors. One for lock and another for unlock.
c) RAP module (optional equipment) that has two outputs that basically connect in parallel to the door switches. There is a third dedicated output and relay for opening just the driver side on a single key fob press. The RAP module also performs the auto door lock feature when you remove your foot from brake and tranny is in gear.
2. When pressing a door lock switch the relays under the dash are activated. You should hear a click near the top of dash under the access panel (panel that starts near top center of dash and goes off to the passenger side and has slots for the automatic headlight sensor). A door lock switch can be held closed and continuous voltage is applied to the actuators.
3. When using the key fob the RAP module will pull the same lock or unlock switch to ground. The biggest difference is that the RAP module will only pull the circuit to ground for about a half second then let go. On the first press a dedicated RAP output will just control the driver door through that dedicated relay. On the second press both doors are controlled (yes the driver's side get's two actuatons when you press the key fob twice.)
4. Please note that the RAP and switches control the same circuit prior to the relays. They are in parallel.
5. The actuators are really DC motors. They work in both directions. Voltage applied in one direction causes a "lock" and voltage applied in the other direction causes an "unlock". Only two wires are really needed at the actuator. But it seems there are more on mine. My schematics don't show more than two wires. Inside the actuators are thermal protection devices. Basically, these devices go high resistance when they heat up thus limiting the current through the motor and protecting the motor from burning up. You can cause these guys to heat up by holding the door lock/unlock switches down or repeated use of switches or key fob.
OK, my problem has been door locks that appear to be getting sluggish over time and eventually to the point that there just doesn't seem to be enough power in the actuators to move the mechanism. Both doors doing this at about the same frustration level.
One thought was dirty relay contacts since the problem was the same with switches or key fob. The relays were common to both sides and since both sides acted up at about the same time this made sense.
The relays are found under the top dash access panel. That piece of dash that looks like it can come off really does! No screws, just get the edge of your fingers under the end closest to the headlight sensor slots and pull up and work your way all the way around pulling up. With that removed there's a relay box right there. Sorry, but that's not it! You need to pop that one off the metal bracket and remove the bracket. It comes off easily. Under the metal bracket toward the engine is a relay box with a plastic cover. Once the cover is off I found the three door lock relays on the left and two others (auto headlight circuit?) on the right. All were the same part number so I simply did some swapping to see if symptoms changed. Nope! I even measured contact resistance and all were no more than 1.5 ohms. Very little compared to the rest of the circuit.
Since the relays checked out I could only think of two other possibilities:
1. High resistance in a ground circuit
2. The door acutators.
After reading many posts on door actuators I'm betting on that. To check for high resistance I could disconnect and fish the two-conductor actuator wire out of the door and connect a light bulb to it. I would then measure the voltage across the light bulb to see if the voltage was much less than about 11v. A light bulb is required to draw current and force a voltage drop across bad (high restance) connections.
Since the door actuators have a built-in thermal protector I am betting this device is going bad (high restance under normal temperature) and limiting the current to the motor resulting in weak action. It seems mine work better in cold temps. so this further supports the theory of bad thermal protectors.
(The following applies to a 2000 F150 XLT with remote keyless entry)
1. Door lock circuit consists of
a) door switches that are grounded when closed for either lock or unlock. (Different circuit in each case is grounded.)
b) three relays that send voltage & current to door actuators. One relay is dedicate to the driver door unlock function when RAP is included. The other relays control both doors. One for lock and another for unlock.
c) RAP module (optional equipment) that has two outputs that basically connect in parallel to the door switches. There is a third dedicated output and relay for opening just the driver side on a single key fob press. The RAP module also performs the auto door lock feature when you remove your foot from brake and tranny is in gear.
2. When pressing a door lock switch the relays under the dash are activated. You should hear a click near the top of dash under the access panel (panel that starts near top center of dash and goes off to the passenger side and has slots for the automatic headlight sensor). A door lock switch can be held closed and continuous voltage is applied to the actuators.
3. When using the key fob the RAP module will pull the same lock or unlock switch to ground. The biggest difference is that the RAP module will only pull the circuit to ground for about a half second then let go. On the first press a dedicated RAP output will just control the driver door through that dedicated relay. On the second press both doors are controlled (yes the driver's side get's two actuatons when you press the key fob twice.)
4. Please note that the RAP and switches control the same circuit prior to the relays. They are in parallel.
5. The actuators are really DC motors. They work in both directions. Voltage applied in one direction causes a "lock" and voltage applied in the other direction causes an "unlock". Only two wires are really needed at the actuator. But it seems there are more on mine. My schematics don't show more than two wires. Inside the actuators are thermal protection devices. Basically, these devices go high resistance when they heat up thus limiting the current through the motor and protecting the motor from burning up. You can cause these guys to heat up by holding the door lock/unlock switches down or repeated use of switches or key fob.
OK, my problem has been door locks that appear to be getting sluggish over time and eventually to the point that there just doesn't seem to be enough power in the actuators to move the mechanism. Both doors doing this at about the same frustration level.
One thought was dirty relay contacts since the problem was the same with switches or key fob. The relays were common to both sides and since both sides acted up at about the same time this made sense.
The relays are found under the top dash access panel. That piece of dash that looks like it can come off really does! No screws, just get the edge of your fingers under the end closest to the headlight sensor slots and pull up and work your way all the way around pulling up. With that removed there's a relay box right there. Sorry, but that's not it! You need to pop that one off the metal bracket and remove the bracket. It comes off easily. Under the metal bracket toward the engine is a relay box with a plastic cover. Once the cover is off I found the three door lock relays on the left and two others (auto headlight circuit?) on the right. All were the same part number so I simply did some swapping to see if symptoms changed. Nope! I even measured contact resistance and all were no more than 1.5 ohms. Very little compared to the rest of the circuit.
Since the relays checked out I could only think of two other possibilities:
1. High resistance in a ground circuit
2. The door acutators.
After reading many posts on door actuators I'm betting on that. To check for high resistance I could disconnect and fish the two-conductor actuator wire out of the door and connect a light bulb to it. I would then measure the voltage across the light bulb to see if the voltage was much less than about 11v. A light bulb is required to draw current and force a voltage drop across bad (high restance) connections.
Since the door actuators have a built-in thermal protector I am betting this device is going bad (high restance under normal temperature) and limiting the current to the motor resulting in weak action. It seems mine work better in cold temps. so this further supports the theory of bad thermal protectors.
