Cursed BMSC for the third time!

[Svashtar]

Hey guys, long time no see. I suck at coming on here unless I selfishly need expertise!

Bought my 2003 pre-decontented MM "new" in 2004 with 300 miles on it (sitting on the lot for 21 months marked as a Grand Marquis! So I beat them way down on the price.) Changed cursed POS BMSC in 2008 or so. Changed it again in 2015. Just failed again. I'm so sick of Ford electronic garbage. Have a Blend door actuator module to install for the last 4 years as well, but it's sitting until I get the courage to tear out my dash and airbag. I'll also need to do something with the o-rings as I recall from here.

The 2nd head unit failed years ago, along with 6 CD changer in trunk, still have to get that out.

ANYWAY, Jim (fastblackmerc) fixed my LCM in 2020, and I'm wondering if he can bulletproof my BMSC once and for all, so just emailed him through the site here, but not sure if he's still around. Please let me know your experiences with the BMSC. Unfortunately have the old original DR rear engine cooling mod so it's a bear getting back there. The plastic T's on the original were replaced with metal ones two years ago, but I'll have to dump the coolant and pull the heater hoses off the firewall and lower bypass hose to get access to the unit.

Thanks for any info. I don't mind doing this once, but multiple times is ridiculous.

[SilverPhoenix]

Jim is still around...

[Turbov6Bryan]

just unplug the old one, zip tie the new one to a ac hose and let it eat. Yes its a pain with the extra hoses there.

[Svashtar]

just unplug the old one, zip tie the new one to a ac hose and let it eat. Yes its a pain with the extra hoses there.

(Let it eat?)

That's what I did, got the power connection off to stop the blower. That's actually a great idea to avoid the hassle and zip tie the new one out of the way, assuming the power connection will reach it, thanks. So obvious it didn't occur to me...!

Just checked and never realized the connector is at least 18" long and doubles back. I'm thinking mount it to a piece of foam right on the plastic fender well, next to the other connectors.

By the way, here’s the selection from RockAuto; anyone have a brand recommendation for a quality replacement? Or all they are pretty much the same? I don't need a pigtail connector replacement that I can see.

https://www.rockauto.com/en/parts/fo...+resistor,6557

[fastblackmerc]

Hey guys, long time no see. I suck at coming on here unless I selfishly need expertise!

Bought my 2003 pre-decontented MM "new" in 2004 with 300 miles on it (sitting on the lot for 21 months marked as a Grand Marquis! So I beat them way down on the price.) Changed cursed POS BMSC in 2008 or so. Changed it again in 2015. Just failed again. I'm so sick of Ford electronic garbage. Have a Blend door actuator module to install for the last 4 years as well, but it's sitting until I get the courage to tear out my dash and airbag. I'll also need to do something with the o-rings as I recall from here.

The 2nd head unit failed years ago, along with 6 CD changer in trunk, still have to get that out.

ANYWAY, Jim (fastblackmerc) fixed my LCM in 2020, and I'm wondering if he can bulletproof my BMSC once and for all, so just emailed him through the site here, but not sure if he's still around. Please let me know your experiences with the BMSC. Unfortunately have the old original DR rear engine cooling mod so it's a bear getting back there. The plastic T's on the original were replaced with metal ones two years ago, but I'll have to dump the coolant and pull the heater hoses off the firewall and lower bypass hose to get access to the unit.

Thanks for any info. I don't mind doing this once, but multiple times is ridiculous.

I can fix the BCM , as long as it is a Motorcraft unit, & your EATC (o-rings & upgrade the button & fan wheel lights with LEDs).

PM me.

[Svashtar]

I will, thanks Jim!


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[1Marauder]

Jim for the WIN! Jim is a baddass!

[Turbov6Bryan]

The new box will get hot, so i just dangle it from that large ac hose. If it fails from use, it just needs unplugged and warrantied. Such a pain to get it out with all the hoses, letting it eat / dangle from the ac hose has worked on one of my supercharged cars for 7 years. Just one replacement and it was under a minute to swap.

[Svashtar]

The new box will get hot, so i just dangle it from that large ac hose. If it fails from use, it just needs unplugged and warrantied. Such a pain to get it out with all the hoses, letting it eat / dangle from the ac hose has worked on one of my supercharged cars for 7 years. Just one replacement and it was under a minute to swap.

Thanks Bryan. I ordered one from the Rockauto list I linked that cost about $5 more, but described it had more robust circuitry than the OEM. (?) Three-year warranty. Another for a little more had a five year, but except for the first OEM unit I’ve had, the last two failed well after 5 years so I went with the sales pitch. I was intending to build a little plastic box for it out of an old DAT tape case with open sides for air to the heat sink, and secure it and the power cord to the fender well to keep things neat, but may just do it your way. I don’t know why I didn’t think of this for the first and second replacements!.

Between work and the rain/wind storms out here I haven’t gotten to the car for other tasks for days, so hope to get it done tomorrow when the part comes.

Now for the EATC all I have to do is take the plunge on the o-rings that Jim mentioned and replacing the blend door actuator that I bought years ago. Hopefully that stops the occasional thumping and fixes the air routing, and it’s not the actual blend box. Just getting the nerve to tear out the dash, as I picture me snapping off something crucial.


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[Turbov6Bryan]

i just leave it open, car doesnt see rain, but i think if you put this in a box, it will retain heat and give it a slow death. I too thought about putting in a sealed box, but got to thinking that the air from the blower unit actually cools this since its mounted inside the heater box. I havent had too much issues with it, dealing with the coolant hoses a few times made me lazy and this is just a simple replacement now.

[Svashtar]

i just leave it open, car doesnt see rain, but i think if you put this in a box, it will retain heat and give it a slow death. I too thought about putting in a sealed box, but got to thinking that the air from the blower unit actually cools this since its mounted inside the heater box. I havent had too much issues with it, dealing with the coolant hoses a few times made me lazy and this is just a simple replacement now.

Thanks, and after designing a plastic box (which would melt in seconds with the heat coming off this thing!) and a hold down, I figured the same thing out and mounted it uncovered off the main AC line as you suggested. Here’s a pic:



It lasted two hours before it failed, and blower went full blast as before. Thing is I had been driving it on the freeway all that time, and in town, and it had been working perfectly. When I got home I left the car idling in park to check the trans fluid, and after 5 minutes it started up full blast on the fan and wouldn’t shut off, same exact failure as before, making me wonder if I had a universal connection problem. I made the mistake of touching the heatsink fins right then and it was hotter than hell, just blistering.

So I took it back onto the freeway, and after just a couple of miles it went right back to normal. I pulled off and stopped and idled, failed again. Turned the car off and waited 5 minutes, back to normal no issues, working perfectly with all EATC settings, Off, Vent, AC, etc. At first MAX AC didn’t kick in the fan, then it did.

So despite their claim that they overbuilt the circuit traces over OEM, it appears to need the ventilation inside the firewall from the fan. OR, perhaps the supposed better circuit traces generate more heat? No idea.

So, I can either 1) Assume I got a dud and ask for it to be warranteed, or 2) Buy another brand, or 3) Just live with it knowing it will fail temporarily if I sit idling too long. Trouble is, I’m picturing a hot day in downtown traffic with no airflow in the engine compartment.

Anyway, please let me know if you mount yours in a different spot? Or let it hang more or something? And I’ll try it. I can say comparing the old and new units I was really impressed with this one, but I can’t have it failing periodically because it’s overheating. Thanks for your input!

(You know, I have some aluminum computer heatsinks designed to fit over old Intel and AMD CPU’s that generated so much heat when you over-clocked them, and I’m actually wondering if I could literally bond one of those to the back side of the circuit board? I’m no expert, but think the solder joints on back of the BMSC circuit board would ignore the adhesive I’d have to use. (?) . Just brainstorming, and there’s a reason they put the heatsink on the side they did. On a computer I’d wire in a fan on top of the heatsink, but on this one even off the backside I think it would melt!)

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[Svashtar]

Going to stretch that power cable as far as it goes and mount it towards the bottom front of the engine. Should get more air down there, just above the lower radiator hose. We’ll see..


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[Svashtar]

FYI, I pulled the power cable off the AC mount and stretched it clear to the front of the car, and mounted it between the battery and the coolant overflow tank. Seems to run cooler there as air comes rushing up from behind the fan shroud. No issues so far.


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[fastblackmerc]

I can repair your old Motorcraft BCM... make it bullet-proof.

[Svashtar]

Thanks Jim, unfortunately the original Motorcraft BCM is long gone, replaced a few years into owning the car, then replaced again about 7 years later with a 3rd party model, and just replaced again with one from WVE, this one looking very well built with thicker trace widths than OEM. I remember seeing a how-to on soldering them I think from you back then, but for $30 just bought a new one. Wish I had sent it to you then. Where I have it mounted now out on the front of the car between the battery and coolant overflow tank seems to be working to get air to it, but we haven't had any hot days yet and I haven't been sitting idling a long time, so keeping my fingers crossed.