Another Key off electrical drain question

[moto67]

77 Cheyenne .. I'm getting a .40millamp key off drain. Pulled all the fuses .. still getting the drain. I took the horn relay off since I have no horn at the moment.. that didn't help. Unplugged CD player.. checked cigarette lighter wire.. and as many other wires I could find. Someone said the main electrical junction on the firewall was dirty on theirs and was causing a short. Mines filthy too.. going to clean that up and see if it helps. I don't think that's it though. Thing is driving me crazy. I have a new battery and new alternator. It's charging fine.

any other ideas?

[krue]

You just gotta keep eliminating things until you find it. Keep us posted.

[lurch115]

this may sound weird...but do you have the wires going into the voltage regulator backwards...had the problem with my truck when i first got it...someone had cut off the original plug and replaced it with 2 female spade connectors....couldn't leave the battery hooked up and the truck parked for more than 8 hours...switched them...and haven't had a problem since

[moto67]

the alternator is the 3 wire internal regulator so that's not it.. Electrical problems can be so frustrating.

[lurch115]

Originally Posted by moto67

the alternator is the 3 wire internal regulator so that's not it.. Electrical problems can be so frustrating.

that is what i am talking about....the 2 wires that go into the internal regulator....if they some how got flipped around they will drain the battery down....

[wedgemon]

Check under the sill plates at both doors for rubbed or screwed thru wires.

[killthewabbit]

I'm sure you've already checked this, but it's bitten me in the a$$ twice now - once on my Chevelle and once on my stepside. Try the dome light. Take out the bulb. The one in my truck was shorted and didn't even light up, but my battery quit dying over the weekend once I pulled it.

Good luck finding it.

[moto67]

I have an aftermarket one with two lights .. they both work so I haven't pulled the bulbs . Checked the wiring along the sill plates.. Those wires were good. Cleaned the firewall main wire junction.. it was grungy.

A .40 millamp draw that I'm getting seems like a lot. If I put a bulb test light to the removed battery positive cable and the battery..it glows bright.. nothing I've done has made it dim even slightly. Thanks for all the suggestions. I was working on it this evening but it started snowing so I gave up for today.

[ureckme]

Mine had some thing like this. it would drain the battery. Mine was the A/C, heater fan relay. Try the relay it's all ways got power to it.
Matt

[moto67]

lurch..yeah someone changed my original plug to two female spades as well. I completely disconnected the alernator both spades and battery hookup and was still getting a draw. I also removed the connectors to the ac/fan relay - it's the one sitting to the left of the ac unit when your looking at the engine right? .. took those off.. nada.. still lighting the bulb. Thanks for everyones suggestions.

[rfmaster]

Moto

Check your starter solenoid post. If it is corroded or has junk built up on it it may cause 40 mAmp leakage current. If you have original wiring in place - disconnect 8 gauge red wire that goes from solenoid to main bulkhead connector this removes all electrical circuits except for starter. If still pulls 40 mA you got bad solenoid. Make sure battery connection is clean and there are no other connections at the battery.

//RF

[moto67]

rfmaster - thanks man.. thats a good tip. I'm going to try the solenoid. The battery is spotless.. brand new and so are all the battery wires. No other connections to it.

[moto67]

I disconected the starter wire from the bulkhead.. and the light went off. At first I was like .. that's it..but then I realized it had to be on still to have the problem.. doh. What else is hot all the time in the truck that doesn't have a fuse. It's not the electric choke cause I tried that already. I've pulled all the fuses and it was still drawing. I took off the horn relay. Could it be the ignition in the column.. the ammeter on the dash?

[rfmaster]

Moto

OK lets trouble shoot this rascal one wire at a time.

Step 1
Starter and starter solenoid
Remove Main bus wire from starter solenoid – it should a solder lug with one # 8 Gauge red wire with another # 16 Gauge red wire lumped together. Measure current leakage from starter solenoid solder lug to the positive terminal of the battery. If it still draws 40 mAmps then starter and solenoid are fine.

Step 2
Alternator
I am assuming that you have a typical three wire 10-SI Delco alternator. Remove both the plastic connector and +B terminal from the Alternator. Wrap some electrical tape around +B terminal lug to prevent accidental short!. Repeat current leakage measurement from starter solder lug to battery as outlined in Step 1. If it still draws 40 mAmps then alternator is probably fine.

Step 3
Main Bulkhead connector
In my ’75, and I am assuming that 77 is somewhat similar, Main DC power +B from firewall DC distribution stud comes through a multi pin bulkhead connector into a back side of a fuse panel. This bulkhead carries most, if not all, power to and from engine bay. It is secured with a bolt(s) to keep it in place and located just below master cylinder. Disconnect engine harness connector (from engine bay side) and examine pins for damage, corrosion, and overheating. Take some Q-tips and isopropyl alcohol to clean contacts if pins show signs of corrosion or discoloration. Get some dielectric grease, similar to spark plug boot grease and pack it in to keep moisture and crud out. Marine stores have this stuff on hand. Repeat current leakage measurement from starter solder lug to battery as outlined in Step 1. If still draws 40 mAmps then leakage is within engine bay, or otherwise leakage is (probably) within cab. Once power gets inside – trouble shooting gets much more difficult.

A typical panel Ammeter uses a # 8 gauge wire between starter solenoid and wire jumper between alternator +B and bulkhead stud as a shunt resistor to measure charging current (or battery discharge). By disconnecting main bulk head connector the two wires that feed shunt differential voltages to the Amp-meter are effectively opened.

Hopefully it (leakage) is in engine bay, or otherwise it a slow circuit by circuit testing. For that you will need factory schematics (not Chilton ) .

//RF

[rfmaster]

Check clock and aftermaket Radio if you have them.

[moto67]

ok I figured it out .. I just don't know how to fix it. It's the Holley electric choke on the carb. I have the positive wire hooked up to the post on the firewall .. then the wire off the negative pin of the choke to one of the bolts on the carb. If I pull the positive off the light goes out. Strange because I tried this before and the light didn't go out then. I took all the connections off the main multipin bulkhead connector and and was still getting a draw so I started pulling everything in the engine and that was it. Now if I pull that positive wire with all the connections hooked up the light goes out. Is my electric choke dead or do I have it wired wrong? Thanks for the suggestions. You really helped me narrow it down.

[f.monroe]

I would say that you nneed to fuse the feed wire to the choke and it should be a switched 12 v source . If it is hot all the time , it is drawing the battery down and not allowing the choke to react to the weather . It should be only on when the truck is running . If it is hot when the truck is off , that could be disasterous if it malfunctioned and caught fire . Frank

[moto67]

thanks frank .. yeah I just went and read the Holley instructions. It was set up this way by the PO. When I bought the truck he told me about the battery drain but said it was probably the aftermarket radio. Wrong. It's the carb. It's setup all wrong. Where do you hook it into? Can you hook it into the accessory plug on the fuse box under the dash?

[moto67]

I think I got it dialed now. Hooked the choke up to a fused connection on the fuse box. Thanks everyone for your help.

[hiway]

This thread has very good trouble shooting info in it. Gonna save it since my buddies 81 that's in my shop has a serious short somewhere.