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Topic: Fuse 8 - .86A draw (Read 1596 times) previous topic - next topic

Fuse 8 - .86A draw

I am getting a .86 amp draw (1.5 ohm from positive to ground with the ground cable removed) on fuse 8 with the car off, all lights off, car just sitting there. I get next to nothing with the fuse pulled, and no measurable resistance. What is the most likely culprit for this? The car was fine Sunday, battery was dead today when I went to drive it.

I know it is basically clock/tripminder, power locks, power mirrors, and illuminated entry. I will add that my alarm is tied to the power lock harness to control them but I sure hope it isn't something weird with the alarm. Should I just start by pulling the door panels and disconnecting the locks/mirrors first? I'm assuming it is a bad door lock solenoid but I need ideas on order of testing. Edit - the solenoids shouldn't have power without the relays on...soooo, pull the relays. I have no clue where they are so I'll search later.

The other thing is that nothing changed besides driving 10 miles on Sunday. No crazy back road driving or anything. I figure a solenoid, relay, or whatever just had enough and is damaged internally.
1988 Thunderbird Sport

Fuse 8 - .86A draw

Reply #1
The door lock solenoid(s) aren't your problem, they receive power from the relays which are controlled by the switches... Could have a stuck relay though, but if they are operating normally, I'd be looking elsewhere... Same deal with the mirrors, they are powered through the switch contacts, no voltage directly applied... I'd think the Illuminated entry would keep the lights activated if it had a problem, again does it function normally???

Leaves the clock/trip minder(doubtful) and your alarm... Ummm

Fuse 8 - .86A draw

Reply #2
I should be able to pull the center console and disconnect the switches to rule out mirrors/locks. The illuminated entry is/was working fine. Tripminder is easy to pull so I'll try it first as it takes me 60+ minutes to get to my alarm. I will add that the alarm door pin sensing wire also apparently also works off of the same wire as the illumination so as you can imagine, once the door handle is pulled up, the alarm trips until the lights turn off and some time passes.

Fuse 8 is also the key in ignition warning chime. I'll have to test that also, see if it works properly. The alarm isn't acting up and powers the door locks/senses the door pins properly so it makes a whole lot of no sense. All I know is that that fuse isn't too important so it isn't as big a problem as initially antited. I wish there was an easy way to separate the circuits from the fuse block without hacking up the harness.
1988 Thunderbird Sport

Fuse 8 - .86A draw

Reply #3
Good luck, problems like this can make you want to pull out your hair...

I'd just about as soon take a beating as pull door panels, but both of my door lock solenoids have puked... One is jammed and I can't even lock the door manually... Oh well, guess I'll have to take my medicine...

Fuse 8 - .86A draw

Reply #4
BTW the courtesy lamps are powered by fuse 8 also... Also radio memory and the premium sound amp have feeds from fuse 8... It's fairly common for the radio(fact and aftermarket) to have issues...

Fuse 8 - .86A draw

Reply #5
So basically pull my right dash apart, center console apart, and pull the alarm out. Most of these should be doable in under an hour. I figure I can check the mirrors and door locks in 5 minutes, tripminder in 5-10 once I find the right bits, and stereo in 15 (it's a huge pain with what's hooked up).

I may need to check something that would allow serious current draw. I hooked the fuse back up once last night, tested for amperage but it blew my ammeter instantly, and I had 1.2ohms of resistance. I'm thinking that whatever it is, it gets bad very quickly. The 15A fuse is fine though.
1988 Thunderbird Sport

Fuse 8 - .86A draw

Reply #6
I forgot that I pulled the stereo memory wire out years ago due to it melting down on the entire wire for no apparent reason (memory wire is smaller than the factory fuse!). The wire was removed down to the fuse block and snipped right where it comes out. If fuse 8 does indeed supply radio memory, that wire isn't it. The premium amp is disconnected and the harness ziptied down with other wires behind the rear seat. I doubt and hope that one's it in any way. I can test this by make sure both ends are disconnecting and checking resistance to ground though.
1988 Thunderbird Sport

Fuse 8 - .86A draw

Reply #7
hey seek,,,
you have an updated thread submitted by me,,,,,,,,,,,,
thank me later.

go buy a voltage regulator for your alternator.

your thread runs parallel with mine,

http://www.foxtbirdcougarforums.com/showthread.php?t=19254

Fuse 8 - .86A draw

Reply #8
I'd be looking at glove box, center console, and trunk lights, too. One of them may not be turning off when it should...
2015 Mustang GT Premium - 5.0, 6-speed, Guard Green - too much awesome for one car

1988 5.0 Thunderbird :birdsmily: SOLD SEPT 11 2010: TC front clip/hood ♣ Body & paint completed Oct 2007 ♣ 3.55 TC rear end and front brakes ♣ TC interior ♣ CHE rear control arms (adjustable lowers) ♣ 2001 Bullitt springs ♣ Energy suspension poly busings ♣ Kenne Brown subframe connectors ♣ CWE engine mounts ♣ Thundercat sequential turn signals ♣ Explorer overhead console (temp/compass display) ♣ 2.25" off-road dual exhaust ♣ T-5 transmission swap completed Jan 2009 ♣

Fuse 8 - .86A draw

Reply #9
I unplugged the trunk light first last night. Now I have to plug it back in - it's a huge pain. I have CCFL's to light up the trunk with no stock switch/bulb. I thought about the center console but it was late and I hadn't eaten my now 1 hour old dinner or even been close to ready to get to sleep at 11:30! Anyways, I didn't think about the glove box last night but I did today - I will be checking these once I jump the car and get it charged this evening. My guess would have been one of the light switches being bad too, especially the center console.

My 3G alternator is out of the vehicle now. It apparently didn't like the load or something as I was at 14.5v for about 1 mile before it began to drop to 13.3v at 1500rpm's (and no higher above) and 12.3v at idle. I drove in 1st and 2nd the rest of the drive. Being disconnected, I can't blame the alternator for this current draw. I have a digital voltmeter in my dash which reads about .05v lower than at the battery and matches my multimeter's readings - it has been helpful with these troublesome "lifetime warranty" NAPA alternators.
1988 Thunderbird Sport

Fuse 8 - .86A draw

Reply #10
ohh,, so now you tell us about your mods,,:D

I had no idea what all you had done,, including the alt being out.

Fuse 8 - .86A draw

Reply #11
Yeah, I apparently left a few things out of the original post that I thought were in there. I wasn't thinking that clearly last night after all the frustration. Anyways, I removed the alternator as it did start acting up yesterday so I thought it was shorting out - apparently not the case. My headlights are disconnected right now as they feed from a custom fuse block in the engine bay - only a relay is fed by the light switch.

Getting a 1.2ohm resistance between the + and -, with the - disconnected from the car and the meter on the chassis, I have a hard time believing a bulb is stuck on. A light bulb is up closer to the 1k ohm mark. To me this sounds more severe like a solenoid that has collapsed internally or a single strand of wire connecting the two sides. You would think with 1.2 ohms though that the draw would be 15+ amps...I know it messed up my multimeter's 10A UNFUSED ammeter the second it touched. I soldered the pcb back together though. It must not be drawing that much if the 15A fuse isn't blowing though.
1988 Thunderbird Sport

Fuse 8 - .86A draw

Reply #12
I won't have a replacement alternator until Saturday either :/
1988 Thunderbird Sport

Fuse 8 - .86A draw

Reply #13
Quote from: Seek;277135
I have a hard time believing a bulb is stuck on. A light bulb is up closer to the 1k ohm mark.

Not so, cold filament resistance in any bulb is FAR LESS than when it's lit... Most bulbs are only a few ohms cold...

Fuse 8 - .86A draw

Reply #14
Hmmm, well I'll be pulling parts here in a few once the battery charges back up. I do thank you guys for the tips!
1988 Thunderbird Sport