printed circuit board question

[dwhyde]

I have a 1971 f-250 and having problems with the battery not charging. i was told if the instrument panel printed circuit board was bad it may not charge. Anyone know if this is true?

[1972hiboy]

I just took a quik peek at a 72 diagram and it doesnt look like charging voltage passes through the printed circuit. Looks like the regulator gets a 12v signal form the ignition switch then the regulator sends charging voltage to the + batt cable side of the starter selonoid thus going to the battery. If you take your cluster out of the truck and turn it over you can usually see a burnt out circuit on one of those printed circuits. it will be a black spaghetti traveling across it.

[chad67]

I ran into this problem-twice. Once when I changed a speedometer, once when I tried to install aftermarket gauges. On the two vehicles I had, a wire ran from the regulator to the gauge cluster and then back. When the circuit was broken (a part of the circuit delaminated on one, I removed the factory gauge on the other) the regulator wouldn't kick the alternator in. I checked everything! I don't think this is "supposed" to affect charging, but it did for me! As soon as I rectified the gauge wiring-no more problems. If you've checked everything else, check the cluster AND the wiring to and from it and all the regulator wiring. A electrical tester is best to use.

[1972hiboy]

I ran into this problem-twice. Once when I changed a speedometer, once when I tried to install aftermarket gauges. On the two vehicles I had, a wire ran from the regulator to the gauge cluster and then back. When the circuit was broken (a part of the circuit delaminated on one, I removed the factory gauge on the other) the regulator wouldn't kick the alternator in. I checked everything! I don't think this is "supposed" to affect charging, but it did for me! As soon as I rectified the gauge wiring-no more problems. If you've checked everything else, check the cluster AND the wiring to and from it and all the regulator wiring. A electrical tester is best to use.

whoa, you would think that with so many of the amp gauges out there that dont move and are presumed dead anyway that they would be so vital to the charging systems operation. Thats bizarre. Luckily I havent had that problem but I'm glad you posted that information.

[chad67]

Both mine had 'idiot lights'. They have a diode (I think that's what it's called) that bypasses the voltage around the light. When the voltage drops to a certain level, the diode stops bypassing and the light illuminates. I don't know why this circuit is needed by the regulator, but it is. I even removed the original gauge afterwards, and it quit charging immediately. I was trying to install gauges instead of lights. After that, I just left well enough alone.

[bluef250]

The resistance from the light causes the alternator to start. If the light is removed a resistor is needed to get the alternator to start.

The "amp gauge" is a charge indicator only. The gauge does not shows ampere only if the system is charging. The gauge is not sensitive enough for the system. Most all ford products had the problem. I don't believe that Ford ever fixed the problem.