Help! Supra doesn't run right

Abe's 1987

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Sep 5, 2017
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Could be a ton of different things.

Connect an ammeter in series on the negative battery terminal so all the current is going through the meter.
Do not turn on any lights or other high current components or you may blow the 10A fuse usually in multimeters.
Trick the hood sensor that its closed.
Fully turn off the vehicle and lock / enable security system (if it has it), everything you would normally do to leave the vehicle.

Get a baseline amperage reading once the vehicle has fully shut off.

Start pulling individual fuses to see which one(s) drop the amperage significantly.
Once you find a circuit that might be the culprit you can continue diagnosing it further.

Would also suggest checking stray current discharge going into the coolant system, this is usually caused by bad grounding / on engine / vehicle ect..
Can also lead to galvanic corrosion on internal coolant system components.

TIP:
Vehicles should have a quiescent or key off load of approximately 10 - 60 milliamps.
Most vehicles are ~ 20mA

(That's 0.020A)

Anything higher and you have too much draw somewhere and should be fixed.

1510702113049329134422.jpg

Which setting would I put the meter on, just double checking to make sure I'll be on the right setting.
 

Abe's 1987

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20171114_174914.jpg

Got another banjo tap and installed it. Still emailing back and forth to get the broken on fixed. They most likely will send me another one so I will have two which I'm fine with as it is better to have a spare.

20171114_174856.jpg

I also received this one today as well. Could use this one as well if I ever need to.
 
Oct 11, 2005
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Which setting would I put the meter on, just double checking to make sure I'll be on the right setting.

red wire plug into 20A max connector.
set dial to A= 20A

Read current. If 0000 then
red wire plug into mA jack.
change dial to 200m

(As noted above, be careful, you short the wire, turn the ignition on, or hit the starter and your unfused 20A connector will melt.)
 

Piratetip

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red wire plug into 20A max connector.
set dial to A= 20A

Read current. If 0000 then
red wire plug into mA jack.
change dial to 200m

(As noted above, be careful, you short the wire, turn the ignition on, or hit the starter and your unfused 20A connector will melt.)

I concur with this.
Make sure you have zero loads on when you have the meter in series.
You want to measure the milliamp current loads of the vehicle off & not blow the fuse in it.

As pi mentioned, the wording on your meter indicates the mA leads are fused and the 20A leads are not.
I have actually never seen a meter with an un-fused ammeter setting, slightly odd.

Just be careful, don't want to blow it up.
 

Abe's 1987

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Ok so I disconnected the battery + and - terminal and removed the battery out of the car. I hooked the red lead to + terminal and black lead to - terminal. Did on 20A max and got 0 then did on mA and still got 0. Hopefully I did it right!
 

Piratetip

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Wait, what?
Without a battery in the system there will be zero power/amperage/voltage anything.

Leave the battery in the car and leave the vehicle positive cable connected to the battery.

Disconnect the negative vehicle cable and connect 1 lead from the meter to that cable.
Connect the other lead of the meter to the battery negative terminal.
Best to use clamps on the leads of the meter so you don't have to hold them.

It needs to be in SERIES which means all current passes through the meter for the vehicle.

Photo example.
http://pop.h-cdn.co/assets/15/47/768x512/gallery-1447710573-pmx0610140a.jpg
https://i.ytimg.com/vi/n5FJDgcdii8/maxresdefault.jpg
 

Abe's 1987

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Nvm i figured how to hook it up. It was reading at 0.06 with hood simulated as closed and everything off. When i take out the radio no 1 fuse in the engine bay it drops to 0. Any ideas?
 

Piratetip

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Ok so I had gone out of town this weekend and came back to find out something has completely drained my battery. I know for sure all light were off and key was not in ignition and ignition is in the off position. When i left Friday volts were at 12.2 and I checked today Tuesday with volts reading at 1.5. Now i need to figure out what is draining my battery. What can be running without the key in the ignition?

Also FYI, a battery sitting at open circuit with no load showing 12.2 V is already down to about 60% SOC.
A fully charged battery at 100% SOC should have an open circuit voltage of 12.7V.
AGM batteries shift slightly higher on the SOC / OCV curve, about ~200mV over standard flooded batteries.

Agreed with pi.
You had to have something else left on.

0.060A draw for say 2.5 days is only going to pull out 3.6 Ah from the battery.
That wouldn't have taken the battery down to 1.5 V in that short amount of time.

What group size battery are you using?
What is the age, brand ect..?

I happen to work as an engineer for the largest manufacturer of automotive batteries in the world, so just trying to understand the full picture here :D
 

Abe's 1987

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No nothing was left on I'm certain. I'm running a duralast 600 cold crank, 750 cracking at 32°f, 110 reverse capacity.

But I am certain that the battery is being drained as I have to use my float charger every now and then. I do leave the hood open always. And I have this aftermarket radio set up

1510716264255573923622.jpg
 

Piratetip

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You took your reading with the hood switch simulated closed right?

So if you leave the hood open always, re-run the test it again exactly how you normally leave the vehicle.

Compare the amperage readings.
 

Abe's 1987

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Yes I simulated a closed hood, Pretty much closed the mechanism that locks the hood down. I'll do the test with the hood opened and let you guys know the outcome tomorrow.

Will also retest the fuel pressure with the fpr vsv bypass to get the correct psi when fpr is plugged in now that I got a new banjo tap.
 

Abe's 1987

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Something else I just thought of is my headlights are all out of wack. When i reset the system as in unplugging the battery for 10 mins the headlights are fine but after starting the engine the light switch seems to go in reverse as in when the switch is in the off position the headlights are on and when the switch is in the on position the headlights are off so I leave the switch in the on the position to keep the headlights off. Thinking my light switch is bad but will test it out later. Maybe this could be draining power as well.
 

Abe's 1987

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Ok so I tested the amps exactly how I always have the car setting. I'm still getting the same 0.06 A being pulled until I pull the 15A radio no 1 fuse then it drops to 0 A after leaving the battery on a float charger for about 24 hours the volts of the battery sits at 11.4 volts as of now.
 
Oct 11, 2005
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As noted 60 mA doesn't seem like enough to do anything bad. But you can leave that fuse out for now just to rule out the radio being the cause. Could be the battery has an internal issue.

As for the headlights, they are pretty complicated. You'll need to spend some time to figure out what is wrong. The combination switch and integration relay 2 is where you might want to start.

http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?S=Main&P=060
 

Abe's 1987

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Going to have the battery tested tomorrow at autozone. I'm thinking the battery is bad cause it reads low volt when plugged in to car then when unplugged it creeps back up on the volts back to around 11ish volts.
 

Piratetip

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One of the cells is probably shorted internally.
If you have access to an acid hydrometer and it has accessible vent caps you can measure each cell.
Its likely one of the cells has a specific gravity close to 1.000, which would be the shorted cell.
 

Abe's 1987

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One of the cells is probably shorted internally.
If you have access to an acid hydrometer and it has accessible vent caps you can measure each cell.
Its likely one of the cells has a specific gravity close to 1.000, which would be the shorted cell.

Ok just had it tested at autozone, guy tested it twice for me. Told me battery is good just needs a charge.

Quick question piratetip, what does it take to become an engineer at a battery industry, which degree is needed, good pay?
 

Piratetip

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Minimum bachelors in your field of interest: Chemical, Mechanical, or Electrical Engineering.

Its possible to move up with just a Bachelors but takes longer and not quite as high.

Lots of people here with masters degrees and phd's as well required for senior engineers / managers / ect..

Yeah the pay is good, but benefits are beginning to go in the shitter.
I believe there are lots of companies that are doing this though across the board, not just us.
They keep passing more and more of the cost of health insurance and retirement related expenses to the worker.

I talk with some of these older employees that started working early enough to receive a pension when they retire.
They complain their pension fund stopped growing a few years ago when they eliminated it.
When they retire they can expect to receive social security, their 401k and a pension combined, plus any side investments if they did that.
They don't seem to fully understand that the younger work force will never even see a pension in their lifetime.

Will be interesting to see in the future how this all plays out.
I anticipate a huge amount of now currently young workforce that will enter retirement and have saved nearly nothing.

I don't expect to receive anything from social security by the time I retire, in 30 years the baby boomers will have likely drained that dry as well.

Anyway rant/ over.
That went way off topic. lol