electrical woes

[jimraelee]

I've noticed for a while now that after a week of sitting the 91 F350 7.3l turbo auto trans ( not sure if anyone needed that info, but to save the questions) will be a little hard to start... I've had a badly corroded pass side positive cable for some time. Today I finally made the priority to change it and give the starting system a good once over to make sure its ready for January's cold temp. When I had both battery positive and negatives off I decided to try a trick an old guy showed me. I hooked up the positives to each battery, then took a test light and inserted in series with the negative terminal and battery cable. Nice glow of the test light. The old guy told me that you will have minimal drain on a battery, especially with new cars and all the electronics on board. I remember seeing a dimm glow. Well on this older non elec truck I shouldn't see much glow. But I do. Next I hook up a DVOM in series the same as the light, leads connected to the amp setting, and also set the DVOM to DC Amps. I get zero, or 0.005a However when I check my 94 Nissan Sentra, I get no light and 0.0a on the gauge.

Question the glow on the light is not good correct??? and Why is he DVOM not showing anything. On on the Sentra, when I had the test light hooked in series with the neg terminal, when i open the door or turn on head lights, I get good glow on the test light, just as the truck just sitting.

mind you I have checked, or unplugged all the usual culprits, ie headlight switch, pulled all fuses under dash, pulled the plug under hood for the GP controller, no change in light. The only time the light goes out is when the Fuse links connected to the relay next to the pass side battery is removed from the circuit.

any thoughts????

 

[franklin2]

Pull the large wire off the alternator and see if the light goes out.

 

[jimraelee]

hmmm u think the alt is draining it.. Ok, will test today

 

[jimraelee]

not the alternator.... I would like to get to the plug for the wires that pass thru the firewall... and unplug it..

 

[franklin2]

If you pulled all the fuses, and the alternator, and the keyswitch was off, there is really nothing else it could be besides stuff added aftermarket that is not fused and hot wired in. Even if you forget to close the doors and the domelight is on, or the underhood light is on, if you pull that fuse the testlight should go out.

When all else fails the alternator usually is the culprit. It has six diodes in it, and if one fails, it will still charge(but not as good) and if it fails shorted, it will drain the battery through the alternator windings. But that must not be it this time.

 

[typ4]

stereo memory??

 

[Black dawg]

ecm or abs relay?

 

[franklin2]

All vehicles are different, but it's generally accepted the drain on the battery from device memories should not exceed around 70ma or .07amps. This much amperage should not light a regular testlight. I believe most vehicles have a drain around 30ma or so.

 

[jimraelee]

Wow... good thoughts.... Yes I pulled all fuses inside and no change on the glow of them light.... the only aftermarket items on the truck are the winch, disconnected when replacing the pos cable, the gauge pod of 3 lights, connected to the fuse block; not checked yet, and rear camper plugs and trailer light plug. I want to pull the firewall bulkhead and see if it goes out. I do knw that if I pull the wires off the relay on the firewall, the test light goes out. Yea Franklin, I checed the light on the nissan, and it had only a slight glow for the amp and high power stereo and its ECM related do~dads. I did have to replace a drivers side battery, Schwab tested it and failed... I have not checked this aftwards. that is another item on the list to inspect.