My 97 Lincoln Mark 8 moonroof doesn't work. I get a thing that sounds like a relay click and the fuse blows. I did a thread earlier, but now I've found a definite problem.
I diagnosed it as a bad relay on the circuit board of the control module. If I unplug everything, the fuse stays good. When I plug in the module, I got a clicking and the fuse blows. Module smelled burnt, relay on the board was warm, and it's the only thing on the board that could click. The smell is also concentrated around that relay. Pretty sure that's a problem.
I can buy a 25-year-old used one for $112, or I was entertaining the idea of just soldering a new relay on the board. Since I'm not well-versed in what parts are what, I don't know what relay to buy to replace it. Not even sure it's the only problem, but a $2 relay and 0.003 cents worth of solder is better than throwing a $100 part at it.
Pics in a minute.
Here is top, bottom, and side.
I'm guessing the relay is the 8 pins. The relay is flush with the board, so there can't be any other components under it to occupy any of those contacts. I guess I'll try to remove it. Nothing to lose.
Get yourself one of these if you don't have one already, will make the job much easier. It's an older style but works well and is cheap.
I have one of these, but haven't ever tried it.
I guess I also wouldn't be opposed to getting a relay that functions the same but is a different configuration. I could pigtail it to a remote solenoid I suppose.
Curtis73 (Forum Supporter) said:
My 97 Lincoln Mark 8 moonroof doesn't work. I get a thing that sounds like a relay click and the fuse blows. I did a thread earlier, but now I've found a definite problem.
I diagnosed it as a bad relay on the circuit board of the control module. If I unplug everything, the fuse stays good. When I plug in the module, I got a clicking and the fuse blows. Module smelled burnt, relay on the board was warm, and it's the only thing on the board that could click. The smell is also concentrated around that relay. Pretty sure that's a problem.
I can buy a 25-year-old used one for $112, or I was entertaining the idea of just soldering a new relay on the board. Since I'm not well-versed in what parts are what, I don't know what relay to buy to replace it. Not even sure it's the only problem, but a $2 relay and 0.003 cents worth of solder is better than throwing a $100 part at it.
Pics in a minute.
A relay shorting to ground internally with no other outside influence is a bit of an unusual failure mode. Have you tried running the roof motor with a Power Probe, etc to confirm the motor itself works and does not draw excessive current?
https://www.ebay.com/itm/295704780464
Here is your relay if you wanna roll the dice.
I would suggest solderwick instead of a sucker. The wick is just a copper braid, lower skill level required. The vacuum ones are trickier, but not too tough to figure out.
93gsxturbo said:
Curtis73 (Forum Supporter) said:
My 97 Lincoln Mark 8 moonroof doesn't work. I get a thing that sounds like a relay click and the fuse blows. I did a thread earlier, but now I've found a definite problem.
I diagnosed it as a bad relay on the circuit board of the control module. If I unplug everything, the fuse stays good. When I plug in the module, I got a clicking and the fuse blows. Module smelled burnt, relay on the board was warm, and it's the only thing on the board that could click. The smell is also concentrated around that relay. Pretty sure that's a problem.
I can buy a 25-year-old used one for $112, or I was entertaining the idea of just soldering a new relay on the board. Since I'm not well-versed in what parts are what, I don't know what relay to buy to replace it. Not even sure it's the only problem, but a $2 relay and 0.003 cents worth of solder is better than throwing a $100 part at it.
Pics in a minute.
A relay shorting to ground internally with no other outside influence is a bit of an unusual failure mode. Have you tried running the roof motor with a Power Probe, etc to confirm the motor itself works and does not draw excessive current?
https://www.ebay.com/itm/295704780464
Here is your relay if you wanna roll the dice.
I have removed the motor and operated it on a 5A power supply from an old computer. It runs great and runs for a long time without tripping the overamp protection. I believe the motor is fine. As soon as I plug in this module and hit the switch, the relay clicks a few times rapidly and blows the fuse. The relay also gets warm in that split second and smells burnt. I don't know how it couldn't be a bad relay. It's pretty obvious that the relay is toast. Whether or not it's the ONLY problem remains to be seen.
Edit for clarity:
- motor and module disconnected = no fuse blow when I hit the switch, so it's not the switch or the wiring
- connect motor to power on the bench, it works fabulously
- plugged in motor to the car (but not installed in the track), no fuse blow, although no motor operation because the module is missing.
- unplug motor, plug in only the module, module clicks and blows the fuse about half second after hitting the switch.... relay on the board warm and smells toasty.
In reply to porschenut :
ordered solder wick. My solder sucker sucks.
i think the next step in the troubleshoot would be to install the motor and hot-wire it (with an inline fuse of course) to see if the mechanism works as intended.
Curtis73 (Forum Supporter) said:
In reply to porschenut :
ordered solder wick. My solder sucker sucks.
You'll probably have the best luck with carefully cutting the relay apart so you can easily heat up and pop the pins out then wick up the remaining solder.
Along this line of questioning... I had some PCB work done decades ago when I had a dead resistor on a dash display, and the guy used a solder-eater tool that buzzed. Not sure how it worked, but it worked brilliantly. buzz-buzz and it was out. Any idea what that tool was?
Yup. Desoldering gun. One of these.
It didn't look like that, but maybe there are different configurations. It seemed to me like a mechanical desoldering, not heat, but this was 20 years ago. It was lightning fast. Like, less than a second fast, and had a pretty loud buzzing almost like a tattoo needle. As I recall it was about the size of a fat sharpie and was cordless.
I just watched a video on YouTube (pine hollow diagnostics 928 episode)of a fellow fixing a complicated multifunction headlight relay with a failed individual relay by soldering in a universal 4 pin relay in for bad one. Look at wiring and figure exactly what inputs and outputs and grounds are. Something to think about. I have a zero success at fixing pcb boards, hate the damn things.
benzbaronDaryn said:
I just watched a video on YouTube (pine hollow diagnostics 928 episode)of a fellow fixing a complicated multifunction headlight relay with a failed individual relay by soldering in a universal 4 pin relay in for bad one. Look at wiring and figure exactly what inputs and outputs and grounds are. Something to think about. I have a zero success at fixing pcb boards, hate the damn things.
I'm not great with PCBs either. One of my problems here is that neither the intarwebs nor the relay itself have a diagram of which terminal is which. I suppose I could cut it open and see if I can figure it out. It might be more than just coil and contacts since there are three limit switches that feed it information. Makes me wonder if it's an "if/then" relay which is above my pay grade.
AngryCorvair (Forum Supporter) said:
i think the next step in the troubleshoot would be to install the motor and hot-wire it (with an inline fuse of course) to see if the mechanism works as intended.
^This. Right now there is one variable that might lead to the same symptoms, and that's a fault in the wiring between the board and the sunroof motor. If the motor works, my suggestion for the next step would be to rule out a short in the wiring.
