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

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.

------------------
" 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 "

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

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.

------------------
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

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.


------------------
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).]

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.

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.

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).]

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.

------------------
" 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).]

quote Originally posted by V8 Formula: DC amp clamp has been ordered, will arrive Sunday.

Note: Watch what else is near the meter... Hall Effect often need "reset" so display is 0 as you move around. meter "book" should tell you same.

Good Battery dead overnight, car is used more then a few mA... Leaving a smallish bulb on might say any bulb etc sucking ~ ½a/500mA. Likely something sucking more.

quote Originally posted by Dennis LaGrua: 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.

The Amp Clamp is way better, safer and faster then using any normal meter. Worse, many "normal" meters are Way Cheap or even given away by HF and others that often can't handle any current w/o problems. If those have a "10a shut" don't trust the meter, probes, or both to handle 10a.

Assume you have a "real" meter say Fluke 77... have only 300mA or 10a shuts. Many others have 250mA max and no 10a range.
Often has issues w/ 10a range trying to read < 1a.

MANY normal meters have no fuses or near impossible to find blown fuses or soldered fuses to replace when you draw too much power thru the shut(s). No fuses often meter is fried at minimum.

Many DC clamps even handles 100+ amps like a engine starter uses. Mine reads 400+ amp so can read inrush current to start the starter.

[This message has been edited by theogre (edited 10-04-2020).]

I know you checked your starter but not directly. I fought this same problem for a long time. Finally the starter failed. I replaced it and no more drain.

Thanks Don, I'll be swapping the engine in the spring which includes a new fuel pump, alternator, and starter. I'd like to know though if there's a short somewhere in the chassis. Hopefully my new testing tools will arrive today so I can get a better picture of what's going on. I'll keep the starter in mind for sure- glad you figured it out.

So I got my battery tester and ran a test. Here are the results:

Battery rating:



Battery charge:



Readings with 120A load:

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

quote Originally posted by V8 Formula: Here are the results...

A few months ago, Cliff Pennock made it so easy to embed images into our posts. Hint, hint.

This I did not know... I can take a hint

Much better!

I'll presume my test results show that the battery is OK?

But in disconnecting the wires from the power distribution block, it broke. So now I have a new one on order from e-bay. Here's the old broken one:

quote Originally posted by V8 Formula: I'll presume my test results show that the battery is OK?

I've never used a battery load tester... but I thought all your previously posted readings were kind of low.

quote Originally posted by V8 Formula: 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...

Patrick- I haven't either but I did watch a couple videos where they show what a dead battery *might* do under load- I saw one pull all the way down to 3-4 volts. Mine only goes down to around to 10.5 under load but that seems low enough to possibly be one bad cell. Hoping Ogre will chime in when he gets a chance.

I wired things up and did some amp testing. I'm basically just trying to get a feel for how this amp meter works. I put the clamp around each power distribution wire near the battery and got a really low reading from each, close to zero but the same as with no wire in it. With everything turned off (but the ecm still plugged in) I clamped around the main red wire from the battery that feeds the power distribution block and got a reading that showed 00.01 A. Basically the same as with no wire in it.



Then I opened the driver's door and it showed 2.01 A

I turned on the headlights with the door open and it read 10.68 (I have LED headlights)

I turned off the headlights but left on the parking lights and had the drivers door open and got 08.71 A

Then with the door shut and the parking lights on I got 06.46 A

I turned everything off again and the reading went back to around 00.01 A

Lots of data and I have no idea what to do with it.

quote Originally posted by V8 Formula: I'll presume my test results show that the battery is OK? But in disconnecting the wires from the power distribution block, it broke. So now I have a new one on order from e-bay. Here's the old broken one: CLICK FOR FULL SIZE

2 post are not very strong and not connected to each other. Alt end connects both and loose stud can make that harder to joint others to bad stud.

quote Originally posted by V8 Formula: ...seems low enough to possibly be one bad cell.

That's what I was thinking when I first read those voltage readings you posted.

Did you "Zero out" the clamp? Just how/where?
What meter? Link so I can search to look up manual.

Amp loads seem normal.
ECM and "radio" pulls max 35mA or 0.035A to keep memory alive to store code, presets etc.

Drain a battery over night or over a weekend is more like something drawing 100+ mA or 0.100+ A
Example: 1 194 bulb for markers, dash, etc. draws ~ 0.27 A.

Others are typical like Open Door is Dome and Foot light eating most of amps you see. (Foot lights only w/ car w/ that option.)

If put main battery cables in the clamp may not see a drain. Unless maybe Starter or alt has problems
Use small wires to battery and others.

Battery Test numbers seem normal. I just look up the "manual" because haven't use one in years to make sure.
More so if not tested w/ fresh full charge.
Note: test should only be done in 10 sec. More just false drain the battery and can overheat the tester.
Is "funny" that manual say use it so meter is horizontal but image shows vertical and many use it same.

Ref: Dead Cell battery should/will die quick under load test and volts will drop and stay there.
Quick load test and good battery volts will rise after test almost same as before testing. Tester is made to emulate normal starter load.

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

Ogre, yes I zeroed out the meter every time before I put it around a wire- it has a little Zero button.

Brand is MeterK, sold at Amazon: https://www.amazo n.com/Mete...2Ctools%2C141&sr=1-4

Manufacturer website: https://www.meterk.com/p-e2275.html

I don't see any download for the manual but I could scan the one that it came with if you're interested.

[This message has been edited by V8 Formula (edited 10-06-2020).]

No manual but helps...
This meter is for bigger jobs but 40A range should read under 1A well enough so to find most leaches.

For an example pull 1 marking light and put meter on 1 wire. Should see ~ 0.27 if you still have normal 194 not LED. If you replace it w/ LED put a normal bulb back to test.

Example Bigger draws, clamp 1 wire to heater blower or rad fan motor or maybe even 1 LED HL. All should be easy test points.

Remember Likely can't or barely see few mA use by Radio, ECM when car is off. Gen2 HL module itself is "on standby" too but Gen2 system usually won't drain the battery like Gen1 w/ iffy parts. Module etc is on F-Link B w/ HL.
If you think you'll pull power plug on module... Module Pins are often weak and solder breaks. Leave it alone as much as possible.

replacing anything w/ LED... power draw can very hard to guess and many products have little or nothing to tell you. Worse If you use "CANBUS" LED they have resistors that eats power and gets very hot very quickly. But "bulbs" should be off w/ switch/car off and doors closed.

Clamp + battery cable... If starter or more like starter solenoid causing a leach likely shows up easy.
Leave clamp on and have helper to start the car... depending on exact starter used should see ~ 120a after inrush current may peg 400A range. May need to learn Data Hold feature to see inrush.
Even w/ good fresh charge battery, If main cables or starter have problems the current can be a lot higher and causes starting problems.

quote Originally posted by Patrick: I've never used a battery load tester... but I thought all your previously posted readings were kind of low.

I wanted to re-visit this. I've got a couple of spare batteries that must be at least 10 years old. I keep them charged up. I just checked one of them that was on the charger a week ago. My multimeter shows that it has a charge of 12.58 volts.

I continue to believe that your readings are a little low.

quote Originally posted by V8 Formula: 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...

You make a good argument... I'll check the battery in my Durango (which never has starting problems ) and see how it reacts.

quote I've got a couple of spare batteries that must be at least 10 years old. I keep them charged up.

Now you're scaring me...