Help! trouble shooting wiring.

[Ghernandez66]

I'm having some electrical issues with my 66 and would like to get some help on how to troubleshoot it or where to start.

The issue is that somewhere the wiring is draining my battery overnight, I can jump start the truck and it will start and charge the battery and if I drive it around town it will start just fine but when it sits overnight its dead again unless I disconnect the battery then it holds charge.

So is there any way to find out what wire is pulling power once the switch is off?

the alternator has been converted to an internal regulated one all I did was jump the leads at the connector where the external regulator was I did some research here for that.

Hope this info helps you guys help me.

Thanks in advance

[franken]

The usual way is to connect a test light between the battery terminal and the cable. Then disconnect things til the light goes out.
I'd start with the alternator and jumpers you put in. Then disconnect the connector at the firewall by the master cylinder.

[leftybass209]

Originally Posted by franken

The usual way is to connect a test light between the battery terminal and the cable. Then disconnect things til the light goes out.
I'd start with the alternator and jumpers you put in. Then disconnect the connector at the firewall by the master cylinder.

This is correct. It's called a parasitic drain test, parasitic load test, or battery drain test. It can also be done with a multimeter set to measure DC amps using a low current setting (10 milliamperes). A test light is a good way to find 1 single source that is draining power. Unfortunately, often times we have more than 1 drain and a test light isn't efficient in isolating that issue.

Start with disconnecting your regulator plug-in as suggested. An alternator CAN draw current through slight diode leakage.

A normal draw for a vehicle full of electronics is between 20-30 milliamperes (.02-.03 amps) and shouldn't be more than 50 milliamperes (.05 amps). So, a truck with minimal to no electronic devices really shouldn't even be drawing the 20-30 milliamps.

Also, when doing this type of test, make sure to disconnect the following components IF you have them-
underhood light
glove compartment light
dome light (if you have door switches in which leaving a door open will cause a draw).

If the alternator plug-in doesn't stop the draw, then you'll have to remove fuses one at a time to isolate which circuit is causing the draw. After each fuse is removed, recheck for a draw on the multimeter. Do not reconnect any fuses until you have removed them all, or found the circuit causing the draw.

I would highly suspect the alternator as the drain point since that's the last thing you modified, but the starter solenoid is another likely culprit. Also, ensure you have good grounds throughout the truck, and your battery cables aren't corroded or damaged (sharp bends and melted or discolored insulation is a good indicator of a possible fault)

Also ensure your battery has a full charge (12.6v+). I hope you get it sorted out!!!!

[Ghernandez66]

Originally Posted by leftybass209

This is correct. It's called a parasitic drain test, parasitic load test, or battery drain test. It can also be done with a multimeter set to measure DC amps using a low current setting (10 milliamperes). A test light is a good way to find 1 single source that is draining power. Unfortunately, often times we have more than 1 drain and a test light isn't efficient in isolating that issue.

Start with disconnecting your regulator plug-in as suggested. An alternator CAN draw current through slight diode leakage.

A normal draw for a vehicle full of electronics is between 20-30 milliamperes (.02-.03 amps) and shouldn't be more than 50 milliamperes (.05 amps). So, a truck with minimal to no electronic devices really shouldn't even be drawing the 20-30 milliamps.

Also, when doing this type of test, make sure to disconnect the following components IF you have them-
underhood light
glove compartment light
dome light (if you have door switches in which leaving a door open will cause a draw).

If the alternator plug-in doesn't stop the draw, then you'll have to remove fuses one at a time to isolate which circuit is causing the draw. After each fuse is removed, recheck for a draw on the multimeter. Do not reconnect any fuses until you have removed them all, or found the circuit causing the draw.

I would highly suspect the alternator as the drain point since that's the last thing you modified, but the starter solenoid is another likely culprit. Also, ensure you have good grounds throughout the truck, and your battery cables aren't corroded or damaged (sharp bends and melted or discolored insulation is a good indicator of a possible fault)

Also ensure your battery has a full charge (12.6v+). I hope you get it sorted out!!!!

Where should I plug in my multimeter? at the battery or where?

[ray_mcavoy]

Yes, connect your multimeter (set to DC amps as leftybass209 said) in between one of the battery posts and the cable you temporarily disconnected from that post. You can do this test on either the positive or negative side but it's generally safer on the negative side.

How To Perform a Parasitic Draw Test -...

[Ghernandez66]

Originally Posted by ray_mcavoy

Yes, connect your multimeter (set to DC amps as leftybass209 said) in between one of the battery posts and the cable you temporarily disconnected from that post. You can do this test on either the positive or negative side but it's generally safer on the negative side.

How To Perform a Parasitic Draw Test - EricTheCarGuy - YouTube

awesome exactly what I was looking for thanks alot guys I will try this this weekend and let you guys know how it goes....

[Ghernandez66]

Originally Posted by Ghernandez66

awesome exactly what I was looking for thanks alot guys I will try this this weekend and let you guys know how it goes....

So I went ahead and tried this and seems like the issue was my jumper in the external regulator plug .... like you guys mentioned ...can anyone guide me in the right direction on how to fix this ? Thanks for the help

[ray_mcavoy]

Originally Posted by Ghernandez66

the alternator has been converted to an internal regulated one all I did was jump the leads at the connector where the external regulator was I did some research here for that.

Originally Posted by Ghernandez66

So I went ahead and tried this and seems like the issue was my jumper in the external regulator plug.

So temporarily unplugging those jumper wires at the old external regulator plug makes the battery drain go away, correct?

If so, I'd recommend double checking how they're jumpered. If the wires are accidentally crossed it could be the source of your battery drain.

The external regulator plug should have brown, red, white, and blue wires. The brown wire is the "exciter" wire that is used to "switch on" the alternator. The red wire is live all the time and is used for remote voltage sensing. The white & blue wires used to connect the regulator to the alternator.

The red wire can be jumpered to either the white or blue wire ... it doesn't really matter which one you choose so long as it eventually leads to the corresponding remote voltage sensing wire on the internally regulated alternator. That'd be the #2 terminal on an SI type internally regulated alternator.

If the red wire is jumpered such that it eventually leads to the alternator's "exciter" terminal (#1 on an SI) it will feed power to the alternator's field windings all the time (even with the key off). And that will drain the battery.

[VetteVet]

Originally Posted by ray_mcavoy

So temporarily unplugging those jumper wires at the old external regulator plug makes the battery drain go away, correct?

If so, I'd recommend double checking how they're jumpered. If the wires are accidentally crossed it could be the source of your battery drain.

The external regulator plug should have brown, red, white, and blue wires. The brown wire is the "exciter" wire that is used to "switch on" the alternator. The red wire is live all the time and is used for remote voltage sensing. The white & blue wires used to connect the regulator to the alternator.

The red wire can be jumpered to either the white or blue wire ... it doesn't really matter which one you choose so long as it eventually leads to the corresponding remote voltage sensing wire on the internally regulated alternator. That'd be the #2 terminal on an SI type internally regulated alternator.

If the red wire is jumpered such that it eventually leads to the alternator's "exciter" terminal (#1 on an SI) it will feed power to the alternator's field windings all the time (even with the key off). And that will drain the battery.

A little visual stimulation for you all.

The jumpered regulator plug.





My way eliminates all that. Locate the brown wire in the firewall plug or extend it from the brown wire in the regulator plug and run it to no. 1on the alternator and splice it into the rectangular plug wire used on the SI internally regulated models. (See Ray's instructions), Then run the red sensor wire as shown. One warning, if you want the ammeter to work you have to wire the conversion as shown. Providing that the ammeter worked before. LOL

[Ghernandez66]

Originally Posted by VetteVet

A little visual stimulation for you all.

The jumpered regulator plug.


Attachment 1464193


My way eliminates all that. Locate the brown wire in the firewall plug or extend it from the brown wire in the regulator plug and run it to no. 1on the alternator and splice it into the rectangular plug wire used on the SI internally regulated models. (See Ray's instructions), Then run the red sensor wire as shown. One warning, if you want the ammeter to work you have to wire the conversion as shown. Providing that the ammeter worked before. LOL


Attachment 1464194

Hmm no wonder.... mine has 12R and 16W together and 16DBL and 16BRN I will change this and see thanks guys

[Ghernandez66]

Originally Posted by Ghernandez66

Hmm no wonder.... mine has 12R and 16W together and 16DBL and 16BRN I will change this and see thanks guys

So I changed the wires and left the battery hooked up for a week while the truck sat whit out starting and got on it last weekend and it started fine ..seems like my problem is fixed since it used to kill battery overnight. .

thanks guys

[_Ogre]

Originally Posted by ray_mcavoy

Yes, connect your multimeter (set to DC amps as leftybass209 said) in between one of the battery posts and the cable you temporarily disconnected from that post. You can do this test on either the positive or negative side but it's generally safer on the negative side.

How To Perform a Parasitic Draw Test - EricTheCarGuy - YouTube

eric-the-car-guy video was a great resourse