Help with dash lights

[RustyPile]

Originally Posted by Coalkracker

If i leave the battery connected its dead within a few hours. If i disconnect it, its good for months. I unplugged the F and R plug at the alternator and it did not make a difference. Ive only visually inspected the wires under the dash to see if anything looks bad. Thats as far as ive gone so far. No testing yet.

That is a preliminary test. It determined that something IS pulling the battery down. Here's the procedure for tracking down the drain. The following is done with the ignition key in the "OFF" position. Remove one of the battery cables (doesn't matter which one) from the battery.. Using a 12 volt test light, attach the probe to either the exposed battery post or the removed cable itself (again, doesn't matter which one).. Attach the lead of the test light to the post or cable, which ever is left. The light should illuminate.. Go to the fuse box and start lifting one end of each fuse. Lift one at a time and each time take a look of the test light.. When you lift a fuse and it makes the light go out, that's the circuit that has the drain.. In some cases, the fuse protects more than one item, so here's where you'll most probably need a wiring diagram for your specific truck. You'll need to know what items are protected by each fuse. When you locate and identify each item on the offending circuit, put the fuse back in place and check the test light again. It should be illuminated again.. Disconnect each item on that circuit, one at a time, until the light goes out again.. The item, when disconnected, is the offending item..

If none of the fuses, when lifted, causes the light to go out, replace the fuses and unplug the harness at the voltage regulator. If the light goes out, you have a shorted regulator.. If the light doesn't go out, disconnect the large gauge charging wire on the back of the alternator... If the light now goes out, you have shorted diodes in the alternator.. The alternator will continue to charge (although at a reduced rate) with 1 or 2 bad diodes..

[Coalkracker]

Oh boy, i think ive got a problem....

[Coalkracker]

So what happens when i do all of that and the light doesnt go out? Because thats what happened....

[Coalkracker]

So would that mean its between the junction on the fender and the harness on the firewall possibly? Or maybe a combination of something in the fuse panel and the alternator or combo of fuse panel and voltage regulator?

[RustyPile]

Originally Posted by Coalkracker

So what happens when i do all of that and the light doesnt go out? Because thats what happened....

Double check yourself, making certain you didn't overlook disconnecting a fuse. Otherwise, you just have to broaden the search and think outside the box.. Have some aftermarket electrical items been added over the years?? Maybe something like a radio, CB, or perhaps some auxiliary lights have been added.. Instead of pulling power from the fuse box, an inline fuse was added to the power lead???? Maybe a relay stuck closed and the item it feeds was disconnected from the relay, leaving the relay powered up..

Leave the test light connected as you conduct the search.. And don't go through the process by disconnecting several items without checking the test light after each disconnect.. Everything except the ignition system is protected by a fuse.. The main power feed to the ignition switch has a fusable link somewhere near the battery. Has some form of electronic ignition or other device been added that has an "always hot" power feed?? Many modern radios and audio amplifiers have this feature. They always have to have power applied to keep the memory feature programmed. Something goes wrong electronically with the device, it starts drawing an abnormal amount of current and runs the battery down.

I forgot to mention this.. I don't like using one of these new test lights that uses an LED.. They draw so little current that you can be fooled into thinking the drain is bigger than it actually is.. My test light is an older design that uses an incandescent bulb.. If you don't have a test light of this type, you can make one using a dash light bulb socket and a pair of alligator equipped test leads. You can also use a good quality high impedance multimeter set to the Ma. scale. It's hooked to the battery the same way the test light is connected..

[RustyPile]

Originally Posted by Coalkracker

So would that mean its between the junction on the fender and the harness on the firewall possibly? Or maybe a combination of something in the fuse panel and the alternator or combo of fuse panel and voltage regulator?

The actual location of the drain is anybody's guess until you narrow it down to a certain circuit.. The important thing to remember is leave each fuse lifted as you progress through the checks.. When you have located the source of the drain and repaired it, reconnect each fuse and check the test light after each fuse is re-installed.. If the light come on again, you have a second drain on that circuit.. Same goes for the alternator and voltage regulator..

Most of the drains I've experienced with these old vehicles is something goes amiss with the alternator diodes or the voltage regulator develops an internal short. I also find cheap aftermarket stereos often cause a drain on the battery if the vehicle sits up for extended lengths (2 - 3 weeks at a stretch) without being driven..

[Coalkracker]

My test light is an led but if i search around i may find my old one if im lucky. My truck doesnt have anything added to the "always hot" junction block on the fender, still has the original AM radio, original points ignition, BUT has a secondary fuel tank with a sending unit in it and a toggle switch under the dash to switch the gauge between tanks, and had a cb at some point in its life. I did remove all the wires from the toggle and cap them. And also pulled the plug for the gauge out of the fuse panel when i had the test light on the battery. I havent even thought of the wiring for the cb, not sure if any of its even left but i will deffinitely be checking around for that tomorrow also.

[RustyPile]

I remember one from years ago. I found a drain coming from the cruise control module.. The drain wasn't strong enough to blow the fuse but it would run the battery down in a couple days.. Lifted every fuse in that car.. I don't remember what circuit the C/C was powered from, but when I lifted a certain fuse the light went out.. Checked every single item on the circuit.. Finally figured out the C/C was (improperly) powered by that circuit. Disconnected the C/C and the light went out.. Reconnected the fuse and started disconnecting C/C items.. Nothing made the light go out until I disconnected the C/C module.. Replaced the module and the drain went away.. Took me a while to find it but that's what I was paid to do..

[Coalkracker]

Come to think of it, I may have been getting voltage on my brown wire from my voltage regulator with the key off for some reason. I think it was around 6 volts. That circuit is supposed to be broken when the key is off. Hmmm now thats got me thinking....

[RustyPile]

Disconnecting the "F-R" plug at the alternator isn't an all inclusive test to eliminate the alternator.. Do me a favor, just to satisfy my curiosity.. Disconnect the 4 wire plug at the voltage regulator and the "F-R" plug at the alternator.. Also disconnect the charging wire on the back of the alternator.. Leave the battery cables connected.. Let the truck set overnight and see if the battery runs down.. As I stated at the beginning of this, Most of the drains I had to deal with on vehicles of this vintage have been either voltage regulators or alternator diodes. So that's where I'm putting my money. If your battery doesn't run down overnight, you'll know where to look. If it does run down, you'll at least know where not to look..

[Coalkracker]

I didnt see your message until this morning but i did what you said and its been sitting for over an hour without any drop in voltage. Normally i would have seen a decent drop by now. What are you thinking...alternator or regulator? Both are under warranty so i can just return either without a problem.

[Coalkracker]

Or is there further testing I can do to pinpoint the issue?

[RustyPile]

Originally Posted by Coalkracker

Or is there further testing I can do to pinpoint the issue?

Just as I suspected!!! Just to be sure, let's wait a few more hours... If there's still no appreciable drain evidence, we have to determine whether it's the alternator or voltage regulator.. Through the process of elimination, one last step will tell us which it is.. Select either the voltage regulator or alternator (not both) and connect the plugs you previously disconnected... My educated guess would be the voltage regulator is the cause.. Let the truck sit again for a few hours.. If the battery looses some of it's charge, the item you connected is the culprit.. If it doesn't loose charge, the item still disconnected is causing the drain..

If it turns out to be the voltage regulator, there's no repairing it.. Replacement is the way to go.. An alternator is readily and easily repaired.. However, you said you recently bought both the voltage regulator and alternator, so replacing the alternator instead of repairing it is the way to go...

[Coalkracker]

Ok well....it isnt the alternator...or the voltage regulator....or anything else with the charging system. I almost dont even want to say it. Remember when I said I was getting voltage on my brown wire at the regulator? Well there isnt supposed to be with the key off as you already more then likely know. Ive been going over wiring diagram after wiring diagram looking at all these wires and thinking over and over again. And I know I should not be getting any voltage on that brown wire with the key off. WITH THE KEY OFF. Im a lot younger then probably most of you guys on here. A lot of you were driving when these trucks were new. Its my inexperience that got me on this one. When i want to drive someplace I get into my suburban and turn the key to the right and put it in drive and go. When im done I put it in park and turn the key all the way back to the left to shut it off and I pull my key out. Think about what I just said.....

[Coalkracker]

Is the key supposed to come back out when turned all the way to the left in accessory position? Well now that I wont make that mistake again I have to move onto the next thing. Is the radio supposed to have a light behind the dial?

[Rick Bollinger]

You can also unplug the key switch that also is a trouble area and the headlight switch. Many always hot circuits in these.

[Coalkracker]

No I figured it out. I didnt realize accessory was all the way to the left, I thought it was one click to the right. Im use to newer vehicles, if I turn my key on my daily driver all the way to the left its off and accessory is to the right. Its a dumb mistake but having an old vehicle is new to me so lesson learned.

[Coalkracker]

What I have to figure out is if being able to pull my key out in accessory mode is normal or if my key cylinder is worn out.

[RustyPile]

Originally Posted by Coalkracker

Is the key supposed to come back out when turned all the way to the left in accessory position? Well now that I wont make that mistake again I have to move onto the next thing. Is the radio supposed to have a light behind the dial?

Uh-huh... You've been leaving the ignition switch in the ACC position.. Basically the same as leaving it in the ON position.. This leaves virtually everything powered up except the resistor wire going to the distributor.. The voltage regulator is powered through the brown/white wire.. That would explain why there was no drain with the voltage regulator disconnected.. OK, write that up to inexperience and a mistake you will probably never make again..

When new, the key can't be removed in the ACC position.. However, given the age of these old trucks, the key wears down along with the lock cylinder and the key can be removed.. That's a sure sign that you need to have the lock cylinder rebuilt by a good locksmith and new keys cut using the cylinder code rather than copies made using the old worn out keys.. This was the case with my truck last year.. The key turned the switch just fine but it could be removed from any switch position.. I had to remove the door lock cylinders to get the key code.. The ignition lock isn't marked with the code. Took everything to a locksmith.. Everything works as it should now..

Remember, gray is the color of the dash light wiring.. If the wiring that plugs into the back of the radio includes a gray wire, then yes the dial is illuminated..

[Coalkracker]

Ok good to know, I have a friend who is a locksmith so I will ask him if he can do it. Im almost finished with getting everything working. I think the only things electrically I have left is the radio, heater control light, back up lights, and heater fan. Im afraid to even turn the fan on considering the size of the mouse nest that was in the glove box.

[RustyPile]

Originally Posted by Coalkracker

Ok good to know, I have a friend who is a locksmith so I will ask him if he can do it. Im almost finished with getting everything working. I think the only things electrically I have left is the radio, heater control light, back up lights, and heater fan. Im afraid to even turn the fan on considering the size of the mouse nest that was in the glove box.

Wear gloves and a mask when clearing out that mouse nest.. Mouse urine is highly poisonous.. The last thing you want is to have the fan blowing all that urine infested dust everywhere.. If you want, we can tackle the other items and leave the heater stuff for last..

[RustyPile]

Back to your plans for LED dash lights.. Read the following thread before you install those LEDs..
http://67-72chevytrucks.com/vboard/s...d.php?t=782020

[Coalkracker]

Ok good to know. I only used them temporarily because thats what i had laying around. I have the correct 194 bulbs for them now I just havent put them in yet. So a little update. I sprayed a diluted bleach solution into the glove box to kill any bacteria/virus just in case then removed the old liner. Disinfected everything around and behind it. Now i have the radio out. Got the case open and cleaned the tuning mechsnism and it works smoothly now. Sprayed de-oxit into the volume rheostat and worked it for a while. I also removed the old bulb but I cannot find a number on it at all. Any idea what kind of bulb it is or where i can find the info?

[Coalkracker]

Well I got everything with the radio working now. Volume, tuner, pre-sets, light. Tomorrow I will try to see whats going on with the back up lamps if time allows me to.

[RustyPile]

I'm not sure of the bulb number, but it is a 12v bulb.. Take the bulb to an auto supply place and just have them match it in appearance with their 12 volt bulbs.. Physical size could be an important factor if it's cramped for space...

When you start on the back up lights, remember those basics.. Check fuses and grounds first... We're probably dealing with more bad/corroded connections..