Wiring Repairs

1989 Mercury Cougar XR7

I spent most of the afternoon and evening working on some electric issues that the car has had since I bought it 2.5 years ago. I hadn't got around to them earlier as there were more pressing issues, like getting the car to run and stopping.

My brother came over to help as I am a huge electrical noob, barely able to read a schematic or run a volt meter. I can solder like a pro though. He was able to determine that 90% of the issues were all tied into one circuit, so we started tracking down the problem there. I started by pulling the lower dash apart, and removing the fuse box. We determined it was fine, so we went to the next location, which was the factory splice under the LH sill plate. There we found a corroded and broken splice. Once I rewired that, the car actually had working interior lights and the key less entry pad worked!

May 24, 2009

I spent the rest of the evening putting the car back together, and verifying everything was working. Other than getting the Firm Ride light in the dash to work again, and doing a minor rewire on my OD delete switch, all options and features are fully functional again! Here is a list of what was not working prior to today:




We thought this had fixed all the issues, but the power door locks still did not work. After doing some more testing, we determined that the splice was likely bad in the wiring. The factory EVTM indicated that it was located in the trunk, so I started pulling the wire harness apart there and headed forward. I got to the back seat, and still had not found it, so I pulled the seat out and kept going forward. It turns out it was almost right next to the one we had already fixed.

Once I rewired the 2 splices which were also rather corrosive, and redid the third for good measure, I had power locks again! The power mirrors still were not operating in all directions, so I swapped out the switch with a spare I had and now they work fine. The last problem to resolve was the glove box light. If I moved the switch/latch around the light would work, but not stay on. I once again went digging through my extra parts, found a switch, and it works fine now once installed. Another small piece of my '93 SC has made it to the Cougar.

The car is getting closer to being complete, and the "To Do" list is shrinking. It will likely be a few weeks before the next update, but the next one should be a good one.


I took a few hours this afternoon to take care of a few small issues. I noticed yesterday that the drivers side lock was not working. I could see the actuator try to pull the rod down, but it wouldn't stay. So I pulled the door panel off an took a look. I notice that the lock cylinder rod was not attached to anything. I pulled the lock out, and found that it was missing the clip that the rod attaches to. I tried the power locks with the lock cylinder out, and the rod moved just fine. The rod must of been hitting on something, or did not have enough tension to hold it down since it was not hooked to anything. I would have likely found this out sooner if I had a key to that lock, but I did not.

Thankfully I have a net set of doors in storage that will likely someday end up on the car. I dug them out and removed the lock cylinders for both sides, and found the ignition was still with them. I replaced both locks on the doors, and everything works as it should. I now have matching door locks. I replaced the ignition as the current one was sloppy and would let you get the key in there crooked, and then it would hang up. This also allowed for use of the correct key with the replacement locks.

While I was working on the passenger side door, I noticed the latch on the door was really loose. I took a closer look and found that only 1 of the 3 bolts were there to hold it in place. I think this might explain why I had a lot of wind noise on that side of the car, seeing how the door would be loose even when fully shut. I added two bolts from the spare doors, and all is good.

May 30, 2009

The next small issue to fix was the "Firm Ride" light in the gauge cluster. It worked fine before I had the dash apart, so I figured something was loose or I had killed a bulb. I pulled the cluster out half way, and found the bulb laying on a brace in the dash. Apparently I had knocked it out somehow when I was putting the cluster back in. Nice and easy fix!

Lastly, I needed to redo my OD delete switch wiring. I had completely forgotten that the factory fog lights will only work with the low beam headlights on. So, my OD delete only worked under the same conditions. Ooops. I found a source of constant 12V power and moved the power wire from the switch over to that. It now will work when ever the switch is on.

Cougar | Info | Plan | Start | 2007 | 2007 | 2007 | 2008 | 2008 | 2008 | 2008 | 2008 | 2009 | 2009 | 2009 | 2009 | 2009 | 2009 | 2009 | 2009 | 2009 | 2009 | 2009 | 2009 | 2009 | 2009 | 2009 | 2009 | 2009 | 2010

Interior Courtesy Lights
Kick Panel Lights
Map Lights in Mirror
Sun Visor Lights
Center Console Light
Glove Box Light

Power Mirrors
Power Door Locks
Keyless Entry Pad
Exterior Door Lock Lights
Under Hood Light
Trunk Light