Parasitic battery drain- 88 Formula (Page 1/3)
V8 Formula OCT 01, 06:43 PM
Sorry this is a bit wordy, but I'm trying to be as accurate as possible.

I bought this car a couple years ago, knowing that it is a high mileage work in progress. One of the things on my gigantic list of things to fix is that the battery goes dead in maybe two to three days after a full charge and no driving.

I got out my trusty 88 factory manual and started troubleshooting. I've been using the method of removing the negative battery terminal and placing a lighted tester between a wire and the negative pole of the battery to see if it lights up. All lights were off, the trunk light is unplugged, nothing is on. I removed each fuse in the fuse block first and checked for light on the tester. Not a single fuse turned off the tester.

So then I went to the back (or is it the middle?) and removed the fusible links A&B pigtail below C500 and found the tester to be illuminated between the pigtail and the negative battery terminal. I checked the orange ECM and the red engine fusible link and found that the light was off on the tester. So that would indicate to me that there is no drain from the alternator, oil pressure sensor or starter solenoid, correct?

But there IS current flowing somewhere after fusible link A or B. So I cut the fusible links off to separate A from B and tested the voltage between the red wire ( from link A) to battery ground and the red and white wire (from link B) to the negative battery terminal. Link A red wire showed 11.9 volts to ground and the link B red and white wire showed 10.9 volts to ground!

Is there a place where link A and link B could connect and be shorted? Ignition switch maybe (C206)? I really don't want to drop the steering column but maybe that's the problem? The car does have a starting problem where even with a fully charged battery, you have to turn the key several times in order for the engine to turn over.

Ideas?

-Rick
Dennis LaGrua OCT 01, 07:54 PM
FIRST STEP
Wash your battery with soap and water. Scrub it perfectly clean. Any acid residue on the battery surface will create a small path of conductance across the terminals and will drain the battery in time. Also remember that the ECM and clock are using a small amount of power so if you don't start the engine in an extended period of time the battery could drain.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

V8 Formula OCT 02, 07:45 AM
Hi Dennis,

This battery is new and probably the cleanest part of the car. LOL

It will drop 1.5-2.0 volts in 2-3 days. That's more than parasitic, it's like a bear in your sleeping bag...

-Rick
theogre OCT 02, 03:18 PM
Think you read the FSM wrong somewhere...
Testing battery "post" to cable just shows enough path to light a small bulb, or worse LED, often doesn't mean much.

Testing anything Hot to ground or battery neg is a good way to fry things when looking for battery drains. Testing w/ light or meter likely only reason you didn't kill other things.

Because Some parts use some power when key is off and light on or Volts on Link A etc mean Very Little.
Even still Test Link A etc to Ground can make parts to back feed the light/meter and cause problems.

Leave battery disconnected.
Charge it.
Check battery volts and Leave it alone.
check several hours, next day or three for 12.6 or more volts.
Low often = bad cell(s).

battery ok, See my Cave, Battery Leaches
faster, buy DC Amp Clamp to test w/o cutting everything... Most Clamps are AC only and can't use here.

FSM is written before DC amp clamps was even made let alone now is common and relatively cheap.

Engine "slow" to start can be many things... fix you "drain problem" first because low/dead battery can make starting problems after charging/change the battery. can cause idle problems to until drive ~ 35mph so ECM can reset.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

fierosound OCT 02, 05:46 PM

quote
Originally posted by V8 Formula:

This battery is new and probably the cleanest part of the car. LOL




quote
Originally posted by theogre:

Engine "slow" to start can be many things... fix you "drain problem" first because low/dead battery can make starting problems after charging/change the battery.



I recently replaced the battery in my Indy because I was having similar problem.
I decided have battery tested before taking half the car apart.

Fully charged showed correct voltage, but Load Test showed 380 amps when it should have been 630 amps.
Minimum recommended for Fiero with any engine is a battery of 525 CA.


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My World of Wheels Winners (Click on links below)

3.4L Supercharged 87 GT and Super Duty 4 Indy #163

[This message has been edited by fierosound (edited 10-02-2020).]

V8 Formula OCT 02, 06:05 PM
DC amp clamp has been ordered, will arrive Sunday.

Battery is disconnected and on the charger. Will check fully charged voltage. Will leave it disconnected until the amp clamp gets here and then check the voltage again and start troubleshooting with 21st century equipment.
V8 Formula OCT 02, 06:36 PM
Fierosound, battery is rated at 650 CCA so should be enough for this car. We'll see in a couple of days. Maybe I'll take a trip to the parts store and see if they can check it...
theogre OCT 02, 10:59 PM
yes, always Test the battery ignore is new because many new ones have problems or repeat draining can cause problems.
Volt test is easy and many have a meter, load test is next but have problems, ideally take battery out if needed and go to shop to computer test.

Volt test often shows a bad cell in minutes because 1 Bad cell often drops to 10.x fast but can take longer if weak cell(s) isn't totally F'd.
V-test w/ "good" output from battery could still have problems.

Many computer testers can even test a low or "dead" battery w/o charging. Saves time and safer too as charging crap battery can be very bad.

Standard Load testing tool sold everywhere for 50+ years is good but Way too many have been beaten badly by store staff and the meter is way off even when meter case looks ok.
(Example: Milton 1260 100 AMP Battery Tester but Snap-on etc has same thing.)

Car and many types of lead battery is Dead below ~ 11.9 volts and trying to start w/ the dead battery can wreck the battery and worse. SI alt like to die for this. CS alt and some others try to self protect but doesn't like it either or can fry when jumped to anything because jumping lies to the alt and alt can't protect itself.
V8 Formula OCT 03, 10:22 AM
Thanks Ogre, I've now got a Milton 1260 on order. They're dirt cheap on Amazon and I'm sure it'll come in handy in the future.

Looks like voltage this morning after a full charge is 12.89. Both terminals are disconnected and it's just sitting in the battery tray. I'll check it in a few hours and again tomorrow morning.

Edited to add: Voltage is down to 12.48 after sitting for an hour and 15 minutes...

Edited to add: Voltage is down to 12.46 after sitting for five hours...

Edited to add: Voltage is down to 12.34 after sitting for 27 hours...

Edited to add: Voltage is at 12.33 after 50 hours...

[This message has been edited by V8 Formula (edited 10-05-2020).]

Dennis LaGrua OCT 03, 11:27 PM
Put a milliamp meter in series with the battery. See what the parasitic draw is and adjust for maximum needle deflection. Now go to the fuse box and pull each fuse out one by one while watching the meter.. If the current draw goes away (needle zeros) after pulling a certain fuse out that is the circuit where your draw/short is.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

[This message has been edited by Dennis LaGrua (edited 10-03-2020).]