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Discussion Starter · #1 ·
I'm having a major drain on my Batt. overnight...test light reveals, with test light alligator clip connected to neg. post, and probe end touching disconnected neg. cable, test light comes on.

Is there a positive wire melted to ground somewhere...have disconnected light switch, AC compressor. radio, Alt., RWswitch, EVP switch and still no solution.
Before I go any further and break all the fragile plastic clips, I wanted to make sure this is the way to pinpoint the problem.
 

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Please show us some clear pictures of this issue
 
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The Tennessee Warden
96 XL, built 357W, E4OD, BW1356, 4.56 gears
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I'm having a major drain on my Batt. overnight...test light reveals, with test light alligator clip connected to neg. post, and probe end touching disconnected neg. cable, test light comes on.

Is there a positive wire melted to ground somewhere...have disconnected light switch, AC compressor. radio, Alt., RWswitch, EVP switch and still no solution.
Before I go any further and break all the fragile plastic clips, I wanted to make sure this is the way to pinpoint the problem.
How much current is the draw? Your meter should give you a number. How many amps? Start pulling fuses one by one (put them back if there is no change on the meter) until the reading drops. Then you have the problematic circuit.
 

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Yo LEATHERNECK
AS ADVISED.
Battery Drain Suspects;
Battery isn’t charging while you drive.
Underhood lamp is always on, if equipped.
Headlight Switch. CORROSION;
Switch Fires, Part Number SW-2103: "...Over the past two years, this office has experienced fires caused by another potential problem in Ford vehicles. The problem exists within the dimmer portion of the headlight switch in Ford vehicles. The light switch involved is a Model SW-2103. These are the pull out type headlight switches usually located in the lower left corner of the front dash of Ford vehicles. The headlight portion of the switch has two pullout positions, the first for parking lights only, and fully out for headlights and parking lights. The shaft of this pull-out light switch can be turned clockwise and counterclockwise which activates a dimmer switch, lowering and raising the intensity of the lighting in the instrument panels respectively. Fully rotating the shaft counterclockwise past a notch activates the interior lights within the vehicles. The potential problem exists within the dimmer portion of this switch. The dimmer mechanism consists of a metallic resistive coil set inside a ceramic disc positioned over the shaft of the switch. The coil is exposed on its front side away from the passenger compartment. The front side of the coil passes across a contact permitting a current to flow through a certain portion of the coil when the switch is pulled our in its first or second positions. The greater amount of coil through which the current is permitted to pass (clockwise most position) creates the greatest resistance and therefore dims the dash lighting to its lowest intensity. The opposite position provides greatest intensity. Through our investigations, we have found that the coil can fail owing to wear and/or possible material defects or damage. A fractured coil can maneuver itself free of the ceramic disc permitting it to come in contact with the metal bracket which mounts and grounds the switch to the vehicle. When this occurs, a current can flow through a portion of the coil creating high temperatures melting the metal material of the coil and possibly igniting surrounding combustibles. This mechanism has been observed in three separate incidents by this office. Two of these resulted in a fire. The mechanism is precipitated by wear and/or defect in the coil mechanism. If the former is true, we expect there will be an increase in fires caused through this mechanism given an increase in service time. To this date the problem appears to be somewhat limited. However, this particular light switch has been utilized in numerous Ford vehicles. Therefore, a small increase in failure rate owing to age and wear could result in a significant increase in fire losses. The SW-2103 Light Switch Assembly discussed above is reportedly installed in the following Ford vehicles: 1986 -1997 F100, F150, F300; 1990-1994 Explorer; 1987-1994 Ranger; 1987-1990 Bronco II; 1992-1997 Aerostar..." Miesk5 NOTE: No Bronco Listed, but this may be the result of typos or incomplete research by the company.
Source: by waltersforensic.com


See:
Battery Testing Procedure TSB 91-10-10 for 85-91 Bronco, Aerostar, Econoline, F-150-350 Series, Ranger; 85-90 Bronco II; 89-91 F Super Duty, F47, F-53, F-59; 91 Explorer, etc.
Source: by Ford @

Loose or Weak Contact at Generator Harness Connector TSB 96-21-4 for 86-93 Bronco
Source: by Ford
"ISSUE: When a generator fails, there are a few failure modes that may cause heat to be produced at the wiring harness-to-generator connector. This excess heat may damage the female terminals on the wiring harness, resulting in increased resistance. The increased resistance produces more heat. When the generator is replaced, the resistance produced by a damaged connector may damage the new generator and could result in a repeat repair, including installation of another generator. High resistance (caused by a damaged connector) will not go away until the damaged connector is replaced.
ACTION: Visually inspect the harness-to-generator connector for damage (heat, corrosion, distortion and cracking) before installing a new generator. Install the Generator Wiring Harness Connector Kit (E5AZ-14305-AA) if the harness-to-generator connector is damaged.
The Generator Wiring Harness Connector Kit (E5AZ-14305-AA) contains the following:
One (1) Red Wire Butt Connector
Two (2) Yellow Wire Butt Connectors
One (1) Wire Connector Assembly
One (1) Instruction Sheet (I.S. 6849)
PART NUMBER PART NAME
E5AZ-14305-AA Generator Wiring Harness Connector Kit
OTHER APPLICABLE ARTICLES: NONE
SUPERSEDES: 95-25-04"

Parasitic Current Drain Test; "...you should be able to trace the "parasitic draw" on the battery in the normal way. Pull the (-) cable off & put an ammeter inline set to the 10A range (or higher if possible) to see how much current is being pulled out of the battery with the key OFF, the doors SHUT, & the hood light bulb REMOVED. Make sure absolutely NOTHING is turned on anywhere on the truck. If it registers 0 or below the meter's next range, switch it down a range until it shows some useful numbers. If it ends up being below 0.5A (500mA), then replace the battery. If it's above that, start by disconnecting all the alternator wires & see if the reading drops under 0.5A. Then move to the fuse block & pull them 1 at a time until there's a significant drop in the reading. That's the circuit that's draining the battery. Follow it to find the problem..."

BATTERY DOES NOT HOLD A CHARGE
L1 CHECK BATTERY CONNECTIONS

  • Inspect the battery cables for loose or corroded connections, especially those negative cable grounds.
Are the battery cables clean and tight?
YesNo
GO to L2.CLEAN AND TIGHTEN the battery cables.
L2 CHECK DRIVE BELT TENSION
  • Tight?
YesNo
GO to L3.ADJUST or REPLACE the drive belt.
L3 LOOSE BATTERY POST
  • Check for loose battery posts.
Are posts OK?
YesNo
GO to L4.REPLACE battery.
L4 CRACKED BATTERY COVER
  • Remove battery hold down clamps and shields.
  • Check for broken/cracked case or battery cover.
Are case and cover OK?
YesNo
GO to L5.REPLACE battery.
L5 CHECK BATTERY
  • Perform the battery capacity test at local parts store.
Is battery OK?
YesNo
GO to L6.REPLACE the battery.
L6 CHECK FOR KEY-OFF DRAIN
  • Have parts store perform battery drain test.
Is correct drain less than 50 Ma (or test lamp off)?
YesNo
Battery is ok!Find the cause of key-off battery drain.

 

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-90 xlt, 351w, e4od, man 1356, 3.55, sag, warn hubs, 35s. -73, 400, np435, d20j twin, 35s
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How much current is the draw? Your meter should give you a number. How many amps? Start pulling fuses one by one (put them back if there is no change on the meter) until the reading drops. Then you have the problematic circuit.
x2 on pulling fuses to narrow it down.
 

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Discussion Starter · #6 · (Edited)
Thanks for all the reply's....under the dash or under the hood fuses or both?

NotaVegetarian...only picture I would have is the Batt. and test light when performing the test I mentioned in my post.

MS88Bronc...I'll check my current draw as you mentioned.

miesk...HL SW is a 4D2212, I did change it several years ago, so may have read a post about the problem w/ the SW 2103.

I need to check out the generator harness and perform the test you outlined.

Battery will be a year old this Dec....the drain occurs when I leave the battery connected over night.
Yesterday, I drove it off and on all day trying to throw a code; it fired right up each time which was usually several hours apart and did also late night. This morning, it wouldn't even show lights that come on when turning the key.
I've done all tests and inspection w/ exception of L5 & 6.

Thanks EL Kabong for your thoughts.
 

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Discussion Starter · #9 ·
MS88Bronc...Okay...hoping it doesn't lead to the hood fuse box; I was thinking about the radio circuit also because couple of times in the past (several months) when opening door to get in, noticed radio screen was on; I started turning off the radio independently when exiting after that.

miesk... Thanks for the reply.
 

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The Tennessee Warden
96 XL, built 357W, E4OD, BW1356, 4.56 gears
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In the morning, when you go to start it (when you'd expect it to be dead), what is the voltage on the battery? If it is still reading over 12V, you probably have a bad ground somewhere. First thing I'd do in this case is clean up all the battery terminals with a terminal brush (or wire brush) and also clean up the connections on the starter relay, and then remove, clean, and re-connect the ground on the engine block (bottom of block behind smog pump or delete pulley) and the hot wire going to the starter.
 

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Discussion Starter · #11 · (Edited)
In the morning, when you go to start it (when you'd expect it to be dead), what is the voltage on the battery? If it is still reading over 12V, you probably have a bad ground somewhere. First thing I'd do in this case is clean up all the battery terminals with a terminal brush (or wire brush) and also clean up the connections on the starter relay, and then remove, clean, and re-connect the ground on the engine block (bottom of block behind smog pump or delete pulley) and the hot wire going to the starter.
MS88Bronc..just saw your post this morning...I haven't checked batt. voltage when it has been dead because the ign. lights wont even light up. I do know that it takes about 30 hrs. to recharge the batt. on 2 amp. trickle charge but yesterday, after pulling all fuses from under dash and under hood and not finding any change in the voltage draw, I started cleaning terminals as you mentioned in your post.

The batt. posts are very clean so didn't mess w/ them; the starter solenoid terminals (starter relay) showed signs of corrosion so I cleaned them up...so I'll work on engine block ground behind smog pump and the hot wire going to the starter.

When I pulled the fuses, I didn't pull any of the relay's out...should I test w/ them out also?
 

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The Tennessee Warden
96 XL, built 357W, E4OD, BW1356, 4.56 gears
Joined
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4,916 Posts
MS88Bronc..just saw your post this morning...I haven't checked batt. voltage when it has been dead because the ign. lights wont even light up. I do know that it takes about 30 hrs. to recharge the batt. on 2 amp. trickle charge but yesterday, after pulling all fuses from under dash and under hood and not finding any change in the voltage draw, I started cleaning terminals as you mentioned in your post.

The batt. posts are very clean so didn't mess w/ them; the starter solenoid terminals (starter relay) showed signs of corrosion so I cleaned them up...so I'll work on engine block ground behind smog pump and the hot wire going to the starter.

When I pulled the fuses, I didn't pull any of the relay's out...should I test w/ them out also?
You should still check the batt voltage even though the lights won’t turn on. That doesn’t mean the batt is dead, it just means the accessories aren’t getting power. The batt could have good charge but a dirty ground is not letting the circuit close and provide power.
 

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Discussion Starter · #14 · (Edited)
You should still check the batt voltage even though the lights won’t turn on. That doesn’t mean the batt is dead, it just means the accessories aren’t getting power. The batt could have good charge but a dirty ground is not letting the circuit close and provide power.
Okay, I'll do that...cleaned up engine block ground and starter wire cable end.
 
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