AM1 fusible link amp drain?

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spencercat
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AM1 fusible link amp drain?

Post by spencercat » Sun Feb 18, 2018 12:52 pm

I'm trying to track down an amp drain from my '84 T4. Putting a multimeter in line with the negative terminal, I find a constant .46 amp drain with the car off. Going thru the fuses and links in the engine bay, I found that pulling the AM1 60 amp fusible link reduces the draw down to .1 amps. WHat does this link to? I looked in the FSM but couldn't figure out what is linked to it. Where should I look?

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Petros
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Re: AM1 fusible link amp drain?

Post by Petros » Sun Feb 18, 2018 3:46 pm

sixty amp? sure that is not the main fusiable link for the whole car? most fuses are in the 15 to 20 amp range max.

did you try pulling each of the smaller fuses in turn? the wire diagram is the only way to track it down and isolated it.

I suspect there will always be a small load from the clock and the primitive ECM, if you have an aftermarket radio with a lot extra features, that could be another source of power draw when off.
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'84 Tercel 4wd (daily driver, with on going mods)
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spencercat
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Re: AM1 fusible link amp drain?

Post by spencercat » Sun Feb 18, 2018 6:05 pm

yes, I guess that's the link for the entire car, so I'm back to square one. On to checking the fuse panel under the driver's dash, and I guess the one next to the passenger side speaker. Any others to check, aside from the fuse box in the engine bay?

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Re: AM1 fusible link amp drain?

Post by xirdneh » Mon Feb 19, 2018 12:02 am

the only time i had this problem it was the radio overdrawing for whatever reason and draining battery if i did not drive car for a week or more.
Love those Tercell 4x4 wagons but they sure suffer from road noise.

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Re: AM1 fusible link amp drain?

Post by splatterdog » Mon Feb 19, 2018 11:51 am

That's the charging current fuse. It might be a bad diode in the alt. Disconnect battery wire at it and recheck. Also, make sure there isn't keyed power keeping the alt turned on.

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Re: AM1 fusible link amp drain?

Post by spencercat » Tue Feb 20, 2018 1:27 pm

Unplugged alternator and drain persists. Checked the other fuses and nothing. Checking starter next

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rer233
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Re: AM1 fusible link amp drain?

Post by rer233 » Tue Feb 20, 2018 2:02 pm

Aftermarket radio??
if it aint there, there's a good chance it won't break!
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Re: AM1 fusible link amp drain?

Post by spencercat » Tue Feb 20, 2018 4:31 pm

OEM radio

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Petros
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Re: AM1 fusible link amp drain?

Post by Petros » Tue Feb 20, 2018 9:41 pm

I have seen corrosion in the fuse box contacts cause a draw. it is not where the fuses make contact, but the metal strips in the back that connect to the wire bundle. try spraying with contact/tuner cleaner, or LPS, or similar. should displace moisture and improve contact.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
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splatterdog
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Re: AM1 fusible link amp drain?

Post by splatterdog » Wed Feb 21, 2018 11:04 am

According to the diagram I looked at, the only thing on that fuse is the alt. Keep disconnecting stuff..

I had one draw on a 70's ford truck that was caused by worn contact material in the ignition switch bridging two contacts together, keeping the alternator field hot.

Draw on any older car shouldn't exceed 10-20 milliamps. Something modern would be around 50ma with all the module memories to maintain.

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Re: AM1 fusible link amp drain?

Post by spencercat » Wed Feb 21, 2018 1:54 pm

I've taken apart the fuse block as shown in the pics, and didn't see any corrosion. Tried unplugging the alternator again but no change. I sprayed contact cleaner at the AM1 fusible link connector and the bar behind it, but no change. No change if I substitute the 40A fusible link for the 60A link.

I can get the amp leak to drop if I disconnect the green connector in the yellow circle below (like if I pull the 60 amp fusible link).

Note the non-standard connector on the positive battery terminal (purple circle).

Do all the wires coming from the fuse block get protected by one of the fuses or relays there (or in the other fuse block in the driver's footwell)?
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Re: AM1 fusible link amp drain?

Post by teranfirbt » Wed Feb 21, 2018 8:59 pm

Eventually all of the power in the car goes through a fuse in one of the boxes. I would start pulling individual fuses with your meter hooked up until you find the right circuit.

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Re: AM1 fusible link amp drain?

Post by spencercat » Sun Feb 25, 2018 1:42 pm

Figured out the drain issue, which was not related to a "key off" drain at all. Rather, the ignition key would not turn to "lock", so it was being removed when in the ACC position. This caused the drain that depleted the battery. Now that I have lubed the ignition switch, all is well (but I have to remember to press the lock button each time, as the key can be removed in any position).

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Re: AM1 fusible link amp drain?

Post by ARCHINSTL » Sun Feb 25, 2018 6:54 pm

Totally OT, but - - - sure glad Goldie has left me alone with these baffling probs!
To me, things electrical are demons sent by Zeus to baffle mere mortals.
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spencercat
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My tercel:: '84 SR5

Re: AM1 fusible link amp drain?

Post by spencercat » Sun Feb 25, 2018 9:40 pm

:) With only a couple dozen fuses and relays, the T4wd is simple to diagnose - try tracing electrical pixies on a modern car with hundreds of fuses!

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