Looking to confirm a diagnosis - Bad VLCM Fan Relay Variable Load Control Module

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BlackOnBlackCobra96

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My Mark VIII runs well when cool, but when it heats up to normal operating conditions, it barely has power and stalls out. My understanding is that the VLCM is bad. This module turns on the cooling fans. The cooling fans work when this module is bypassed. I think I need to swap out this part. I believe the part number is F4LZ12B577AA, which is no longer in production. Thoughts as to whether this is the issue? Thoughts as to where to get this part?
 
BlackOnBlackCobra96 said:
My Mark VIII runs well when cool, but when it heats up to normal operating conditions, it barely has power and stalls out. My understanding is that the VLCM is bad. This module turns on the cooling fans. The cooling fans work when this module is bypassed. I think I need to swap out this part. I believe the part number is F4LZ12B577AA, which is no longer in production. Thoughts as to whether this is the issue? Thoughts as to where to get this part?
Click to expand...

What year is your car?
 
Here is the full situation. The car runs and drives perfectly as long as the temperature is below the 'M' in Normal on the temperature gauge. If it goes to the 'M', the car looses power or stalls out. On one cold day, I started the car and let it sit to warm. When I checked on it, the car had stalled. I was able to restart, but could barely get the car down the driveway and just left it. When it cooled down, all was normal again. Previously, I took it to a shop to replace the fuel pump and they noticed this issue. They stated that the cooling fans were not coming on and said that this was the issue, but that they were unable to locate the part. The shop did bypass the module, gave power directly to the fans, and the fans worked fine. The car has 13K miles on it and had been sitting in my grandmother's garage for 7 years. All fluids have been changed. The car also has a flashing airbag light, the power antenna only goes down, and the door chime goes off when braking (all items I'm going to fix, but I do not think are related).
 
There was no reason to bypass the module and hack up wires to directly power the fan if that's what you needed to do to check something. All you have to do is pull the coolant sensor plug off of the sensor body and the fan will be triggered into fail safe and run at full power as long as the car is running.
 
My first guess would be plugged catalytic converters. You can check that using a vacuum gauge. Vacuum should be somewhere between 18 to 22 in of vacuum at idle. As the engine heats up vacuum will drop significantly, if the converters are plugged. You can also use a laser temp gun to check temp of converters. If they are excessively hot, they are probably plugged. Second issue would probably be with fuel system. Fuel system would have to be varnished up after sitting that long.
 
The issue happened today while in really slow traffic. The thermostat went to 'M' in Normal and stalled out. I couldn't get it started until I cranked on the heat all the way and let the car cool down. It's clearly a temperature related issue. It's not a big deal now, but will be in the summer.
 
Take a picture of your VLCM & post it. They are year & color specific. If not Rich, Jay or I more than likely have it. If not, there's a guy on my page named Carlos Mejia that is parting out a 95 & a 94 I think. He DEFINITELY has to have it.
 
Alex, read through the posts, he doesn't need a vcrm. They are called vcrm's on 1st gens, variable controlled relay module, on 2nd gens they are called vlcm's variable load control module.
 
UltimateSVT said:
Take a picture of your VLCM & post it. They are year & color specific. If not Rich, Jay or I more than likely have it. If not, there's a guy on my page named Carlos Mejia that is parting out a 95 & a 94 I think. He DEFINITELY has to have it.
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I'm taking off on a business trip and won't have access to the car until Saturday. If you are parting out a '95 and have a working VCRM, I'd be glad to purchase it from you. I also need an airbag module and some interior bits and pieces such as a rear passenger-side ash tray in grey (my ashtray door broke) as well as the trim piece that covers the rear passenger seat rail, also in grey. If you have these parts, please reach out to me.
 
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