Hi all,
I just got a (very) used 1997 Mountaineer and it has the oddest problem. Neither the key fob nor the power door lock switches on the front doors work to lock the doors of the truck. They work fine to unlock the doors, but just not locking them. That seems straight forward enough, but the oddity comes in that the power lock switch at the back of the truck (by the tailgate) works fine for both lock and unlock.

Any ideas? Broken wire to one of the front switches disables both and the key fob?

TIA
-K2JJB

 

Hi Tia, I have a 1999 explorer and I have the exact same problem. So I hope someone will have an answer .I'm thinking there might be a few relays and the locking relay is defective as apposed to the unlock relay.


Mrmenis

 

Hi Mrmenis, I took appart the door panels today (unrelated project, I was putting in a new lock cylinder) and while I was there I took a look at the wiring on the driver's side and passenger side lock switches... they are all OK and check out as working with a multi-meter. It does not seem to be a cabling issue into the doors at all. My next step is going to have to be tracing the darn thing back to what I assume is a control module that the key fob also links into and seeing if that might be at fault.

What still baffles me is that the power lock switch at the back of the truck is able to lock and unlock everything just fine, so if it is a relay that is doing it then it must be that the rear lock switch has its own relay to control the solenoids... which just seems weird to me, but who knows. I need to get a real wiring diagram for the truck to see what is really there before I butcher something by accident.

I will continue to see if I can get this fixed... it is one of two remaining "items" with the "new" truck....


-K2JJB

 

Thanks for the response K2JJB I've had no luck so far, I'm still trying to get a hold of a wiring diagram. Please let me know if you come up with anything.

mrmenis

 

The 97 Explorer/Mountaineer locking system has three separate relays. A "drivers door unlock" relay (does just what it says it does) is activated (pulled to ground) by the first click of the fob or the first turn of the unlock motion with outside key. The second click or second turn (within a second or so) pulls a second "all unlock" relay to ground. Pushing unlock on the rear hatch switch uses this relay. A third "all lock" relay locks all doors when it is pulled to ground.

These three relays live in a combined module (along with the trailer lights relay) behind the left rear interior trim panel. You can see them by taking off the access cover to the jack. The relay cluster mounts upward, just under the upper trim panel lip. Off a couple of inches toward the front of the truck, mounted at about a 45 degree angle, is the anti theft module (Ford calls this by a funky name - the RAP - Remote Antitheft Personality module). The key fob works through this module in getting signals to all the standard chassis/body electrics.

The "all lock" function specifically works my taking a pink wire with yellow stripe (P/Y) on the all lock relay to ground. There are two P/Y wires on the same connecter pin to this relay. One wire goes only to the rear hatch switch. This is what is working when you push that switch. This wire is being grounded by the hatch switch, the all lock relay is thus energized, and all doors then lock.

The second P/Y wire goes via a harness forward along the left side of the truck, winding in this harness down across the left rear wheel well. Somewhere near the front of the rear door opening, there is a splice (Splice S337) that brings three separate wires together to this connection. All of these wires have the same P/Y coding. One wire goes to the drivers door switch, one to the front passenger switch, and one doubles back and goes to the RAP. Grounding any one of these three wires will lock all doors, just like grounding the other P/Y wire at the all lock relay using the rear hatch switch does.

Your problem is somewhere between where this single P/Y wire (the one that does not go to the rear hatch switch) attaches to the all lock relay in the rear quarter trim panel area, and where it makes the three-way splice. I bet when you look at the relay cluster in your rear quarter panel, and see the single connector pin on the relays module that has two P/Y wires, one of those wires has been pulled off - perhaps when someone was grabbing for the jack, etc.

I have a 97 Mountaineer. The best thing I ever did was buy the Electrical And Vacuum Troubleshooting Manual off ebay for about $20. They are listed there all the time. Note that the Explorer is almost identical, but has a couple of high end unit variances. I suggest you get one of these if possible.

I also have the paper factory service manuals. They can be had on ebay for $40-50. The troubleshooting manual has only the wiring diagrams, no troubleshooting text. You can also get a one year subsciption at www.alldata.com to view all these manuals online for about $20. You can print any page. I prefer books when trying to trouble shoot, but everything in the manual is in the alldata system.

By the way, the Troubleshooting manual is labeled "Preliminary". There was never a final version!

Hope this helps. Let me know how it goes. These electrical gremlins can wear you down.

Dennis

 

Dennis, thanks for the detailed reply... I'll put the info to use and see what I come up with

-K2JJB

 

Dennis,
I was able to pull the back cover and locate the relays as detailed in your reply. I tracked down the wire(s) in question and both went to the block just fine. I then began a back track of them with an ohmmeter and a pin checking for continuitity in the wires. I managed to locate a break in the system under the passenger seat and where it runs forward to the front. I am not sure where it is exactly but that does not matter. I just tapped into the wires at each point I knew was good and put a jumper in.

All my door locking switches, and the remote as well, now work.

Again... thanks very much for your post it was exactly what I needed to get me on the right track! Now I just need to fix the damn blender door (quick fix did not work) and I will have removed the gremlins from this truck.

 

Glad things worked out for you.

 

I have not had the time to get started but I'm sure I'll find the same or similar cause.Thanks for the info in advance

mrmenis