On very cold mornings and days when my truck is outside in the cold, the alternator does not charge until the inside of the cab warms up. The truck runs on the battery only. The dash and dome lights start off OK, but slowly go dim. The gauges eventually die. Radio dies. The heater fan, which I need to warm up the cab, goes slower and slower. I hear beeps from the computer. The idle gets rough and if I let it stall, I have to jump it off to restart. THEN, I hear a click and everything comes back on, as normal. Never does it above freezing. Never throws a code. I've tried a heat gun and a hair dryer to try and blow hot air under the dash, but all that's done is burn my floor mat. I know not to even try and drive anywhere until it warms up, or I'll lose gauges and everything else. A Dodge friend thinks it's the body control module. Like to know what Ford folks think.

UPDATE: This problem has come back each winter for the last 4 years, since I had my present stereo installed. Fortunately, it has to get real cold for this to happen and it that only happens once or twice a year. So, each of the past winters I have dealt with it. Last week, it was very cold every day for a week. Since no one has suggested any component issues, it must be a loose bus or cable connection, or something the stereo installers pulled loose. Anyone have a link to instructions for dash removal?

 

This might help:

"Question: 1999 Ford F-150 mileage: 105,000. I have a problem and I think it is my alternator, but I am a little unsure. Periodically, my lights dim and everything electrical will slow (ac, heater, etc.) After a short period, they will return to normal. At first I thought it might be a short, but it does not occur when I hit a bump nor does it go away on bumpy roads (once it stopped while sitting still). The last time it happened, my truck stalled when I stopped. It wouldn't restart. Then, about an hour later, it started as if nothing was wrong. Any ideas?

Answer: Here are some things to check. Load test the battery. Check that the battery cable connections are clean. Check for 12 volts to starter solenoid with the key in the start position. These things should be checked first then the ignition switch, starter and starter solenoid. One of these may be faulty."

found here:

http://www.2carpros.com/makes/ford/f1501.htm

 

Thanks. I will keep that in mind. Because it only happens when it is 28 degrees or colder, it is difficult to troubleshoot.

Now I'm thinking it is the alarm. I was standing outside the truck on the passenger side and inadvertently pushed the alarm button on my keyring. I heard a relay click behind the dash that sounds the same as the relay I hear click when the truck finally warms up. If you ever tried to start your truck while the alarm is going off you know the electrical system is disabled. Still haven't pulled the dash apart. Could use a link for an expert on Clifford car alarms.