Resoldering control modules to eliminate warning lights

Merkur Scorpio / XR4Ti Technical Library - Check here for answers to common questions, problems and modifications.

Moderator: John Brennan

Post Reply
Merkur Club web site
User avatar
Ray
Level 7
Level 7
Posts: 4338
Joined: Sun Oct 24, 2004 10:40 am
Location: CT, USA

Resoldering control modules to eliminate warning lights

Post by Ray »

Okay so i know a lot of us have that always on, sometimes flashing, etc lights in the center stack. Also my lamp failure indicators never seemed to work right after mid last year. so i took out the modules, located above the ECU behind the glove box. This requires removing (sliding) two long C shaped clips off the body to free the panel, then you take the wiring out. I took some pics, as well.

Here we have the offending module boxes.
Image

here we see how they are crimped. to gain access to the boards i just used a screwdriver and bent the metal back a bit.
Image

here is the light control module, i started to already resolder this one. it wasn't in bad shape, but i redid all the points anyway.
Image

another closer view
Image

this one (the other module) was a bit nastier. not only did we have corrosion, two of the lines were broken (fixed in later images)
Image

zoomed out view a little.
Image

another view. at this point i think i had already started to resolder.


Image

resoldering complete. i used some teflon coated 20ga wire to reconnect the pins that had broken leads on the board.
Image

all done. i also sprayed the boards with electronic grade clear coat to protect them for at least another 22 years.
Image


to recrimp the case around the board i just used some vice grips and lightly pressed them back. then i filled the pins for the wiring connector with dielectric grease and resinstalled in the vehicle.

After resintallation, everything works wonderfully.
-Ray
1985 Ford F150 - Tow Missile
1985 Merkur XR4Ti -#141 CP "Miss Daisy"
2005 Subaru LGT
http://www.cartct.com
User avatar
John Brennan
Level 8
Posts: 11630
Joined: Wed Jun 18, 2003 4:19 pm
Location: Scottsdale, AZ "Summer Is Coming"

Post by John Brennan »

Bravo, sir-- well done! Outstanding post; belongs in the FAQ. Thank you. :thumb
This is my car, and these are my people!
2015 Fiesta ST
2020 Edge 2.0 Ecoboost
Rocky Leitch
Level 3
Level 3
Posts: 264
Joined: Tue Feb 06, 2007 10:36 pm
Location: Ocean Shores, WA.

Post by Rocky Leitch »

Hey there, good job.
I'm new at the technical wonders
of my toy. So the questions may seem
out there. What did you use to clean up
the corrosion? Or did your solder take care of
as well?


Rocky
Hellooo Nurse!!
User avatar
Ray
Level 7
Level 7
Posts: 4338
Joined: Sun Oct 24, 2004 10:40 am
Location: CT, USA

Post by Ray »

you cannot use anything abrasive as that will damage the connections on the board, they damage very easily. the resoldering takes out most of the corrosion. the stuff you see left aren't actually connections but just posts for a heat sink. use flux or flux cored solder and you'll be fine.
-Ray
1985 Ford F150 - Tow Missile
1985 Merkur XR4Ti -#141 CP "Miss Daisy"
2005 Subaru LGT
http://www.cartct.com
BuzzBomb2.3
Level 3
Level 3
Posts: 285
Joined: Thu Nov 12, 2009 3:46 am

Post by BuzzBomb2.3 »

This was the #1 reason I removed the center console and replaced it with four autometer gauges. Of the several cars i'd seen, I've never seen one work.

You sir have skill. Nice job. 8)

-Liam
my8950
Level 7
Level 7
Posts: 1762
Joined: Wed Jan 19, 2005 11:07 pm
Location: Detroit

Re: Resoldering control modules to eliminate warning lights

Post by my8950 »

Anyone still here?
If so, are these photos still available somewhere?
I tried doing this last fall, however nothing changed on the module, actually did both but neither made any difference.
I'm wondering what was here that isn't now and if it is something I missed.
hEaT
Level 7
Level 7
Posts: 3902
Joined: Mon May 07, 2007 10:12 pm
Location: USA

Re: Resoldering control modules to eliminate warning lights

Post by hEaT »

my8950 wrote: Mon Jun 24, 2024 1:13 pm Anyone still here?
If so, are these photos still available somewhere?
I tried doing this last fall, however nothing changed on the module, actually did both but neither made any difference.
I'm wondering what was here that isn't now and if it is something I missed.
From what I remember, it was just pictures of reflowing each solder joint. Heat it up with an iron and add more solder if needed.
my8950
Level 7
Level 7
Posts: 1762
Joined: Wed Jan 19, 2005 11:07 pm
Location: Detroit

Re: Resoldering control modules to eliminate warning lights

Post by my8950 »

hEaT wrote: Thu Aug 08, 2024 8:04 am
my8950 wrote: Mon Jun 24, 2024 1:13 pm Anyone still here?
If so, are these photos still available somewhere?
I tried doing this last fall, however nothing changed on the module, actually did both but neither made any difference.
I'm wondering what was here that isn't now and if it is something I missed.
From what I remember, it was just pictures of reflowing each solder joint. Heat it up with an iron and add more solder if needed.
I agree, I recall the same as well. I actually did this with the module I have and a spare already when I posted before. No change in performance of the module, hence the reason I was asking if there was any other information. It's not a big deal to me if it works or not since it hasn't really worked since I've had this specific car, however, it would be cool if it did actually work as it should.
hEaT
Level 7
Level 7
Posts: 3902
Joined: Mon May 07, 2007 10:12 pm
Location: USA

Re: Resoldering control modules to eliminate warning lights

Post by hEaT »

my8950 wrote: Thu Aug 08, 2024 8:29 am
hEaT wrote: Thu Aug 08, 2024 8:04 am
my8950 wrote: Mon Jun 24, 2024 1:13 pm Anyone still here?
If so, are these photos still available somewhere?
I tried doing this last fall, however nothing changed on the module, actually did both but neither made any difference.
I'm wondering what was here that isn't now and if it is something I missed.
From what I remember, it was just pictures of reflowing each solder joint. Heat it up with an iron and add more solder if needed.
I agree, I recall the same as well. I actually did this with the module I have and a spare already when I posted before. No change in performance of the module, hence the reason I was asking if there was any other information. It's not a big deal to me if it works or not since it hasn't really worked since I've had this specific car, however, it would be cool if it did actually work as it should.
I feel you. I've tried the similar fixes on my tach and moving the pot, and it still barely works.
my8950
Level 7
Level 7
Posts: 1762
Joined: Wed Jan 19, 2005 11:07 pm
Location: Detroit

Re: Resoldering control modules to eliminate warning lights

Post by my8950 »

hEaT wrote: Thu Aug 08, 2024 9:56 am I feel you. I've tried the similar fixes on my tach and moving the pot, and it still barely works.
yep, same with that post as well...I've taken apart and soldered the connections on each for the tach, still works, but also still reads 30-50% low. Basically no change except me doing a lot of detailed work to try and fix it. :(
User avatar
brokencase
Level 7
Level 7
Posts: 1887
Joined: Sun Dec 06, 2015 12:18 pm
Location: PA

Re: Resoldering control modules to eliminate warning lights

Post by brokencase »

On the Scorpio's tach (and I assume the same for XR4ti) there is a open frame potentiometer that calibrates the tach.

Because it is subjected to humidity the resistance changes and the tach reading goes off.

Note the position of the potentiometer, and then give it a slight wiggle back and forth and it will usually restore proper operation.

Best solution is to remove the open frame potentiometer and replace it with a sealed unit. I don't know what the resistance is.
Specialization is for Insects
Post Reply