Door latch polarity reverse?
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Post Fiend
Joined: May 2006
Posts: 10,007
Likes: 4
From: Central Florida
Door latch polarity reverse?
I just checked my front doors again. Continuity on the striped wire when the latch is closed. Near 12v on the striped wire when latch is opened and 0.12v when the latch is closed. Meaning, when the latch is opened, the switch closes and sends ground forward. So the switch is normally open and (-) polarity. I believe this is correct. So the switches are right, however when the key is in the ignition and the driver's door is closed the bell dings. When both front doors are open, closing one makes the lights come on (one front door open, one front door closed.) I don't believe it is a problem with the switch and the alarm is triggered by the dome light and not the door switches, so the alarm is not a part of the problem. Is there a normally closed door trigger that I should have used instead of the normally closed I have now, or is there a way to program the input in the VSS? The truck is a 2002 F250 superduty 5.4L, 4x4, Lariat.
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Post Fiend
Joined: May 2006
Posts: 10,007
Likes: 4
From: Central Florida
The problem is when both front doors are closed, the door ajar light is on, when either door is closed the door ajar light is on. Only when both front doors are open is the door ajar light off. The rear doors have no effect.
Moderator
Joined: Jan 2001
Posts: 56,980
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From: Virginia
See if you have a GEM module in your truck. I know sometime around those years they quit using them. If you have one, then it may be going bad because of a windshield leak. The GEM module in the trucks equipped with them, controlled all those functions, and the door switches were wired right into it.
I think the later trucks used what they call a "body module" which receives all the door switches.
I think the later trucks used what they call a "body module" which receives all the door switches.
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Post Fiend
Joined: May 2006
Posts: 10,007
Likes: 4
From: Central Florida
I have replaced the Cluster/GEM already and ford programmed it "as built". I believe the door triggers go into the VSM first. I replaced the VSM first because when the problem started, the truck's power door locks and keyless entry failed.
Elder User
Joined: Nov 2001
Posts: 892
Likes: 1
From: Duluth, MN
Here's a post right out of the shop manual: On vehicles that are equipped with remote keyless entry, the door ajar switches provide a ground signal to the body security module which subsequently provides a ground signal to the instrument cluster via the UBP network and illuminates the door ajar indicator. On vehicles not equipped with remote keyless entry, the door ajar switches are hardwired to the instrument cluster and provide the ground to illuminate the door ajar indicator.
hope that helps
hope that helps
Elder User
Joined: Nov 2001
Posts: 892
Likes: 1
From: Duluth, MN
Looking at the wiring, you should have a 12 volt power wire coming into your door switches(YE/BK for driver front and GY/RD for passenger front). then check for proper ground circuit BK wiring leaving the switch.
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Post Fiend
Joined: May 2006
Posts: 10,007
Likes: 4
From: Central Florida
That's what I had/did. Near 12v on the striped wires and they drop to near 0v when the latch is closed.
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