Question
fuse box
QUESTION: 79 midget
what is the best and easiest way to figure out what is on each post of my fuse box?
is it standard or could a previous owner have changed them?
what things are on it and how are they usually grouped?
also, i would guess that it would be easy and no ramifications if i would change it out to a new blade style box.
ideas? opinions and expertise appreciated
picture of what i have attached
currently something is keeping the red light on dash on when car is off and without key. (there is a yellow light, red light and blue light but i don't know their functions) the battery drains. if i disconnect the second fuse from top (don't know how they are numbered) the dash light goes out and the battery doesn't drain. currently with all fuses in place, my horn, blinkers and running lights do NOT work. my flashers and wipers do work. high beams work. there is no radio. i noticed that the little lights hiding behind the dash that are for the switches seem to always be on. i removed the bulbs.
i don't know what fuses are for what. also, the wiring diagram that i found of yours is a bit intimidating but i guess if i can figure out how to break it down i might understand.
any info and expertise is appreciated
ANSWER: Hi Cherie,
Wow! from your picture I would say you have your work cut out for you. NONE of those wire ends are from Lucas original wire ends so there is no telling what some one has done.
I learned early while working on electrical problems to pick only one circuit to trace and follow. I usually start at the load and test there first and then work my way to each connection in the harness to a switch or what ever works the item and test until I reach the source (battery) Then pick the next item that does not operate and do the same.
If I were you, I would start with the ignition red light system. Just under the choke cable is a turn signal indicator and under that is the light switch and just to the right of the light switch are two lights. The top light is red and the one under that is a blue light.
The red light is a "Ignition On" light and it also is the "Alternator Charge" light. When you turn on the ignition key the light should light up and when you start the engine the light should go out indicating that the alternator is working.
If that is the red light that is on with the key off, do this. Go under the hood and unplug the Alternator wires if it is one big plastic plug. If you have several different wires individually then only on plug the small size wires and see if the light goes out.
If the light goes out then you have either an alternator or regulator problem.
If the light does go out then remove the one or two large brown wires form the back of the alternator and take a 12v test light and put it between the large brown wires and the pin or pins that the wires were plug on to. If the test light lights up you have a bad alternator. If the test light does not light up you probably only have a bad regulator (inside the alternator).
If however, the red light on the dash did not go out when you unplugged the alternator then you for sure have a wiring problem. In that case you need to lay out your wiring diagram and start tracing that alternator circuit.
It sometimes helps to enlarge the diagram and use colored pencils to mark on your diagram as you trace that circuit. The charge circuit does not go through the fuse box so that has nothing to do with your problem.
Never try to guess what is wrong and keep concentrated on only one circuit and in this case, is you charge light circuit.
After you fix that and other things don't work right just pick only one of them and follow the trail on the diagram with a colored pencil.
That procedure is a 100% correction of a circuit and electrical failures.
Howard
---------- FOLLOW-UP ----------
QUESTION: Ok, following your directions i put back all 4 fuses and connected battery. Red light was on without key. I unplugged connector on back of alternator (one thick brown wire, one thin brown wire and one brown with yellow stripe). Tested thick brown and got positive test. Tested thin brown and got positive test. Brown and yellow negative.
I see these wires go to regulator. Regulator has thick brown and thin brown going to same place on regulator. Both test positive. Other wires on regulator are green and white which goes to elect fuel pump (tests positive) and thick white with red that goes into dash (tests negative)
The prev owner states alternator is new. He just confirmed only approx one month old. Although this could be false i believe from your instruction you are stating it is prob the alternator. . Any further test i should do to confirm?
ANSWER: Cherie, you need to run the test I stated and what are you talking about the regulator? The regulator is internal inside the alternator.
I told you to test between the large brown wire and the terminal that it came off of. You do need to confirm that the brown wire is positive but the test is between the brown wire and the terminal it came off of. That terminal goes to a diode pack in the alternator and if you can light a test light BETWEEN the terminal and the wire it shows that the diode pack is bad. And you didn't tell me if the dash light went out when you unplugged the wires off of the alternator. If the light goes out then it proves that the alternator is bad. It does not matter if the alternator was installed 5 minutes ago if it tests bad it is bad.
There are only three wires on the alternator and they are a large brown wire (hot all the time) and small brown wire (hot all the time) and a small brown w/yellow wire that is the idiot light.
Howard
---------- FOLLOW-UP ----------
QUESTION: sorry, i was confused about the testing.
1. when i unplug the harness to the alternator, the red light on dash goes out.
2. i meant solenoid, not regulator (brain, don't fail me now)
3. when i use my tester and connect from the harness (thick/large brown wire) to the terminal that it goes to on the alternator, the tester light does NOT come on
4. when i use my tester and connect from the harness (thin/small brown wire) , the tester light does not come on
what other things would make alternator a suspect? wouldn't the car die if i disconnected the battery when running if the alternator was bad? because i tried that and the car still ran.
AnswerThe fact that the light goes out when you unplug the alternator proves the alternator and /or the internal regulator is bad.
The way the system works is the dash idiot light is powered by the ignition switch and the light is grounded by the alternator when the alternator is not turning meaning that the brown w/yellow tracer terminal on the alternator is a ground. But as soon as the alternator is turning that terminal becomes positive and since the brown w/yellow is positive due to the ignition switch powering the bulb then the light goes out because it is powered on both ends.
Now with your car when the Ignition switch is turned off the bulb circuit through the ignition switch has several other items connected so there is a ground through those items and when the alternator diodes fail or a portion of the regulator fails it routs the power from the brown wires (which are positive all the time) back through the idiot light to those items and lights the bulb even though the switch is off.
You either have the small brown wire and the small brown w/yellow tracer mixed up on the alternator or you have a failed alternator.
Here is another test of the alternator
Put a volt meter across the battery terminals (not cable ends) and read battery voltage. (12v +) then start the engine and set the RPM at 1500 and read battery voltage. It should read 13.8v to 14.5v
Howard
