Can't Find Battery Drain '88 Silverado

Anonymous-0

Well-known Member
I have spent a fair bitbof time trying to track down
thev12.96 volt/1 amp battery drain on above vehicle.

This and the low rpm stalling problem came with the truck
four years ago. The truck's in very good shape for an old
WI vehicle. I have not driven it but 100 miles in the years
I've owned it.

I have systematically removed every fuse (and in-line) in the
block as well as all relays on the firewall. I also
disconnected the alternator. Nothing stops the problem.
Bed is removed. Vehicle has no glove box light.

The thing that bothers me is, the previous owner messed
around under the dash installing a security system, multiple
cigarette lighters, etc. All such appliances have been
removed & all known bare wires covered.

I may just have to install a battery disconnect switch & be
done with it, but there goes all my radio pre-sets, etc.

I'm no quitter, but the battery drain & stalling problem
continue to elude me.


..............Glenn F.
 
(quoted from post at 19:36:35 03/16/14) I have spent a fair bitbof time trying to track down
thev12.96 volt/1 amp battery drain on above vehicle.

This and the low rpm stalling problem came with the truck
four years ago. The truck's in very good shape for an old
WI vehicle. I have not driven it but 100 miles in the years
I've owned it.

I have systematically removed every fuse (and in-line) in the
block as well as all relays on the firewall. I also
disconnected the alternator. Nothing stops the problem.
Bed is removed. Vehicle has no glove box light.

The thing that bothers me is, the previous owner messed
around under the dash installing a security system, multiple
cigarette lighters, etc. All such appliances have been
removed & all known bare wires covered.

I may just have to install a battery disconnect switch & be
done with it, but there goes all my radio pre-sets, etc.

I'm no quitter, but the battery drain & stalling problem
continue to elude me.


..............Glenn F.

Since the problem with the stalling and the drain happened about the same time perhaps the problem is the computer?
 
Just a question but heard on TV that GM had millions of vehicles with a stalling problem because of defective ignition switches. Could that be a problem for you?
 
Voltage is not a measure of any drain or current flow. Are you saying you've got a full 1 amp of current when you run an amp-gauge in line with one of your battery connections? If so that is a lot. Make sure you wait a minute after hooking the amp gauge up and see if the drain tapers off. Many do.
 
Hello GlennF,

Here something for you to try. Remove the electrical firewall plug. A single bolt in the center. Then disconnect it from the engine side. This will tell you which side of the cab you need to look. If the draw drops, now you can jump one circuit at the time. It is like hunting, but you may be able to isolate the circuit at fault this way. Lots of bad ignition switches out there!


Guido.
 
Glenn, To find the draw in this old of truck is kind of simple but hard to explain. You need to do a parasitic load test with a amp meter. It should be less than 50 mil amps. As far as the stalling it may have nothing to do with the draw. If it only stalls at idle may have to do with the throttle body. My E-mail is open. If you e-mail me I will get you info to do this and illustration of what you need. I have been a GM tech since the 90's. David
 
This may be an angle to check on the stalling problem:

The computer is looking for oil pressure at the oil pressure sender. It must be at least 7 psi. I have been told. At times the oil pressure on my '88 got to the point of turning on the warning light and the dash gauge on my '88 would go to zero.

On the 'net I found that if the pressure went much lower the engine would cut off, usually at stoplights and stopsigns where the rpm is low.

I was told by a good mechanic the problem was probably sludge plugging the oil pressure sender. I put a gauge in my truck to monitor the actual pressure produced. Warm at idle it was about 10 psi.

Several oil changes in the last 2 years-At least 9 altogether-it has been several months since one of these episodes. I have also switched from 10w30 to Rotella 15w40 which brought the warm oil pressure up to about 15 psi.

One thought about your electrical problem: We worked on a mower in the shop where I work that had a partial ground through the starter (the solenoid on the starter). It was killing batteries too.
 
Good suggestions. I am certain the oil pan is clean. I have not checked out the starter. It functions perfectly. Visualizing the internals of a Chevy starter I am trying to think of a possible problem.

Can anyone speak to a starter causing stalling/battery draining problems? I haven't monitored it closely, but my battery will be stone dead sooner than any sitting vehicle I've known. Maybe six weeks.

I know talk is cheap, but I really appreciate each of your input.


Glenn F.
 
When set on volts it reads 12.72+. When set on amps it reads 1.

I am not as smart as the tool I'm using here. Thank you for being patient with me.

Glenn F.
 
If you go with the disconnect switch could you run the radio straight off the bat. with a fuse and off/on switch of its own?
 
I wouldn't think the starter would be the cause of the drain.

If you'll follow the positive battery leads, as each branches off to feed different circuits, start disconnecting them until the volt reading drops. Which ever one drops the reading is the direction to pursue. If the trail leads to a multi-connector plug going through the firewall, open the connector and look for green corrosion. That stuff is conductive.

Be very suspicious of any add on accessories. They can be connected to more than one power source, who knows if they were ever properly installed, assume nothing!

Possibly when you find the drain and correct it, the idle problem will go away also. If not, find the idle speed servo on the throttle body, remove and clean it with carb cleaner.
 
IMHO, if the "puter and fuel pump relay are functioning, the engine will run with the oil pressure sender removed and the hole plugged.

As long as the "puter is "seeing" a signal from the pickup coil in the distributor, it will keep the fuel pump relay and thus the fuel pump activated.

The oil pressure switch is a BACKUP to that system.
 
First take a GOOD look at the battery connections... I used to think the GM side-terminals of that era were the cat's meow, but they haven't aged well.

Clean them, make sure no plastic from the insulated covering is getting pinched between the terminal and the connection on the battery and that the little bolts are in good condition and draw the connection up TIGHT to the battery.

Or, perhaps someone has butchered one or both of them with a clamp on "repair" end that is loose, freaky or corroded?


Then, start by fixing the battery drain (if there is one).


The voltmeter reading is MEANINGLESS here. Toss the meter aside and connect a simple unpowered test light between one of the battery cables and the battery. If it glows, viciously disconnect stuff 'til it goes out, and, obviously the last thing you disconnected is the parasitic load.

You have pulled fuses, well, now take the cover off of the electrical center at the RH side of the firewall and start unbolting fuseable links from the battery-powered buss bar.

If that light is glowing keep at it, there's SOMETHING that can be disconnected that will stop the draw!

Once you figure that out, move on to the stalling (if it still occurs.)

As to the stalling, it may be a completely different matter... fuel pump relay, (or even a fuel pump that gets "flaky" when alternator output/battery voltage drops a bit at idle), a cracked magnet or bad pickup coil or electronics in the distributor, idle air control motor sticking, or EGR valve sticking.

To check 4 the EGR sticking, pull the vacuum hose off of it and plug the LINE, then drive it. If stalling ends, it's a bad EGR, and it will need to be replaced. (Driving it over a certain number of miles with the EGR disconnected will set a trouble code.}

Also, GM made the incredibly smart decision to put engine control system ground wires on the thermostat housing bolt and possibly intake bolt(s). The aluminum those parts are made of corrodes and poor grounds develop. Figure out a place on the intake or an accessory bracket the the wires will reach, clean to bare metal and bolt the grounds tightly.

At this point, I would make up some new accessory ground wires from #10 wire and connect that common ground point to the battery (-), the frame, and the sheet metal of the cab.

You can beat this thing... just gotta be systematic about it, and check and fix the most likely things FIRST!
 
(quoted from post at 23:30:28 03/16/14) First take a GOOD look at the battery connections... I used to think the GM side-terminals of that era were the cat's meow, but they haven't aged well.

Clean them, make sure no plastic from the insulated covering is getting pinched between the terminal and the connection on the battery and that the little bolts are in good condition and draw the connection up TIGHT to the battery.

Or, perhaps someone has butchered one or both of them with a clamp on "repair" end that is loose, freaky or corroded?


Then, start by fixing the battery drain (if there is one).


The voltmeter reading is MEANINGLESS here. Toss the meter aside and connect a simple unpowered test light between one of the battery cables and the battery. If it glows, viciously disconnect stuff 'til it goes out, and, obviously the last thing you disconnected is the parasitic load.

You have pulled fuses, well, now take the cover off of the electrical center at the RH side of the firewall and start unbolting fuseable links from the battery-powered buss bar.

If that light is glowing keep at it, there's SOMETHING that can be disconnected that will stop the draw!

Once you figure that out, move on to the stalling (if it still occurs.)

As to the stalling, it may be a completely different matter... fuel pump relay, (or even a fuel pump that gets "flaky" when alternator output/battery voltage drops a bit at idle), a cracked magnet or bad pickup coil or electronics in the distributor, idle air control motor sticking, or EGR valve sticking.

To check 4 the EGR sticking, pull the vacuum hose off of it and plug the LINE, then drive it. If stalling ends, it's a bad EGR, and it will need to be replaced. (Driving it over a certain number of miles with the EGR disconnected will set a trouble code.}

Also, GM made the incredibly smart decision to put engine control system ground wires on the thermostat housing bolt and possibly intake bolt(s). The aluminum those parts are made of corrodes and poor grounds develop. Figure out a place on the intake or an accessory bracket the the wires will reach, clean to bare metal and bolt the grounds tightly.

At this point, I would make up some new accessory ground wires from #10 wire and connect that common ground point to the battery (-), the frame, and the sheet metal of the cab.

You can beat this thing... just gotta be systematic about it, and check and fix the most likely things FIRST!


Or use a 12 volt lamp.

Dusty
 
GlennF,
It's hard to say what is draining your battery. I've had a leaky diode on a lawn mower causing the problem. A seat belt solenoid release on an old 78 wouldn't shut off. Diodes in alternator. The clock in 75 chrysler new Yorker. A tiny light in sun visor.

Best advice is connect digital ammeter between negative terminal and ground, then start pulling one fuse at a time. Or listen for a sound when you connect negative terminal back to battery, that's how I found the seat belt solenoid release problem. If there is a big enough drain, you should see a spark.

Add to the list of drains, the light under the hood isn't shutting off when the hood was closed.
You could have a light in trunk, glove box, inside car, someplace draining.

All the drains I've had in the past, sure there are more. GOOD LUCK. Finding drains could take days. In the mean time, remove negative terminal each time you stop to make sure it's not a bad battery. Take battery to town and have Auto Zone or any other place. Get a free load test.

I save time going to town, I bought a battery conductivity tester. It gives me a digital readout of the battery's cca without putting a drain on it.
Post back and let us know what you find.
George
 
You cannot read volts and amps at the same time with hand-held digital multimeter or VOM. The hookup is different and the multimeter gets is red wire plugged into a different port IF you want to use the 10 or 20 amp scale. Many newer auto computers draw power all the time. So do alarm systems and electric remote-controlled accessories. So do radio memory chips. You need to learn how to use the mulitmeter and hook it up correctly.
 
"connect a simple unpowered test light between one of the battery cables and the battery. If it glows, viciously disconnect stuff 'til it goes out, and, obviously the last thing you disconnected is the parasitic load."

This is a good procedure, but the parasitic draw must be great enough to power the light -- not all parasitic draws are that large. An analog voltmeter connected between the battery cable and the (empty) battery terminal will show if a draw is occurring. The Hoyt AGB-1 is convenient (prices have really climbed over the years). With it, draws such as a wet insulator on an Allis B starter switch have been found.
Meters
 
since you have removed all fuses. relays and alternator loads,and still has a draw--you should check the feed wire from your battery source to the fuse blocks. Also check the positive battery cable for a slight short
 
I agree with Bus Driver. A test light between the battery and battery wire will glow dimly till the faulty circuits fuse is pulled. A light works better because there are intentional drains that will render a meter useless.
My 89 Supremes drain was in the radio. I just installed a switch in the line to the radio. Good enough.
 
Meter useless? Oh, come on. If there is a small drain a mulitmeter will easily detect it with the milliamp scale.
 
Well, as a test, I tried unplugging the sender on my '88 K1500. It would not start until I plugged it back up.

The first thing that comes to mind with the starter is a carbon trail in the insulator on the solenoid. In the particular case I mentioned, the engine was under warranty and we just replaced the starter to save labor.

To test this on the Chevy, Just remove the + battery cable and the 2 hot wires going up in the wiring harness, and bolt them together. Keep the connection insulated, of course!!!! If the drain goes away, its was finding a ground in the starter or solenoid.
 
I've had discharge problems like that which were cured by unhooking the radio's continuous power supply for the presets... The radio itself used to get hot. And just in case you're wondering... that was on a heavy truck with 3 gr 31 1100 amp batteries and it would drain them dead over night.
I'd be inclined to hook a clamp type current meter over the battery cable and start pulling fuses again until the draw disappears. If it doesn't disappear... start unhooking cables until it does... then at least you know what direction to go.

Rod
 
Clamp-on inductive amp meters are handy but I've yet to see one that is sensitive enough to measure small milliamp draws. Just about any $5 multimeter has a milliamp scale that does the job just fine.
 
You need a battery switch. Kent-Moore used to have one to do just what you're doing for about 50 bucks. I made the one
on the right for side term. batts. out of a top term switch like on the left, just add a short cable and tap a 3/8 hole. Close the switch, hook an amp meter lead to each side of the switch, set on milli amps and open switch, shouldn't read over 25 or 30 milli amps. Always close sw before opening door
a149849.jpg
 
Glenn, gab posted a pic of what you would need to use to find a draw. I reread all the post and you said that the truck goes dead after about 6 weeks. That is normal. The keep alive memory in the ecm and radio will draw enough to bring the battery down. The spec is less than 50 mil amps on a draw. If the truck goes dead in less than 3 weeks. Then look for a draw. Most vech. in that age the battery will last about a 4 weeks. To days vech. with all the computers will only last about 2 weeks without being driving. some of todays vech will be dead if you leave the key on for 20 min. If are going to let the truck set that long install a battery disconnect. Put the truck back together and we will start looking at the running problem. David I don't like doing this but here my email [email protected]
 
Curious and bored today so I checked my 90 1/2 ton GMC, 12 ma, yours should be similar.
Suspect any after market junk first, radio ,alarm, add on remotes, ect.
a149850.jpg
 
Another option - if you find the draw is not excessive - is to install either a trickle charger, or if truck sits outside, a solar charger might be enough to offset the draw. I have a 2011 Silverado that sits for weeks at a time or about a month between startings and it has never gone dead so far, although I do notice the battery has sounded a bit weak when I go to fire it up. It sits in my basement which is heated, so would be easy to put a trickle charger on it. As to hooking up a meter to check draw, I would simply disconnect the ground cable, then simply connect one meter lead to good ground, the other end to battery ground - this way you would not require a special connector or battery disconnect. Once you connect the meter, begin disconnecting fuses one at a time to discover circuit with largest load. I had a 92 Silverado that when I had a hitch and trailer plug installed the person installing inadvertently hooked something up and energized my electric fuel pump (hot all the time). I would never have noticed had I not noticed the slight "hum" of the pump when I walked past the truck, and was fairly easy to find the source of the sound. Of course that would have dramatically shortened the life of the pump, as well as killed the battery in short order, but I found this within an hour of getting home the day he installed the hitch, and trailer plug. I cannot recall what he had done, but was easy to fix if I recall.
 
Unfortunately I don't know howlong it takes to run the battery down as I have not yet put it on the road. It sure seems like a discharge of 12.72 (last night's test) is excessive. I know the battery will be stone dead in 2-3 months. In fact the last time I left the battery hooked up through the winter in an insulated building it was stone deadin the spring and an otherwise good battery was junk.

Glenn F.
 
I will test it again tonight, paying closer attention to the amp draw. I am currently getting a draw of 1 amp, which is enough to drain a battery over night. I understand normal is no more than .05. As you can see I am not very knowledgeable with such things. Learning.

Glenn F.
 
If you are going to leave it set for more than 3 weeks you should either disconnect the battery or hook up a maintainer. My dealer recommended that I unhook the battery on my 2013 Silverado when I left it sit for 2 months, and I did.
 
True, a multimeter will detect intentional drains. That's why it's useless trying to find a fault. On the othe hand, a small bulb will not glow at intentional drain currents.
 
(quoted from post at 20:58:13 03/17/14) True, a multimeter will detect intentional drains. That's why it's useless trying to find a fault. On the othe hand, a small bulb will not glow at intentional drain currents.
Useless?
I think not.
 
The same company makes a quick disconnect for side terminal batteries. Few auto parts stores stock them, but they can order them for $35. If you look online at Amazon.com and Ebay you can find them for about $15-$20 including shipping.
 
Thanks Pete! That's something I should check as I almost never move the cruise switch to the off position.
 
Have a nephew with a modern "Silverado". Had the same problem with a dead battery after sett'n a couple of days.

We spent hours looking for the draw. Finally we both gave up. Tough to do for a couple of airplane mechanics..........

Finally took the truck to the dealership and they spent 2 days just to find out that the driver's seat motor had a shorted connector that was laying next to the seat frame.

Goes to show...... just another convenience item that was installed from new. Electrically adjustable seats.

HTH John,PA
 
They won't measure milliamp draws but they will measure down to the amp. If this thing is going dead over night... I doubt we're talking less than an amp.

Rod
 
I know the dealer might have told that story, however it is hard to believe that a short to the seat frame would not have either blown a fuse (very likely), or burned the truck to the ground. But some believe that any electrical issue is caused by a "short" :). If the dealer is anything like some of the so called "techs" I have encountered they simply swapped parts until the problem went away, and told the customer it was just a "short to the seat frame". Reminds me of a time I had a pickup in the body shop (low mileage truck) to have a bed replaced due to a rear end collision. Strange how the truck ran fine going in to the shop, but failed to start to pull it out of the shop. After a week of the truck sitting outside and still no bed on it, I called them asking what was happening. He stated the "fuel pump had failed while in the shop", and it was waiting on the other shop to replace under warranty (yeah - right). After yet another week they finally had it ready, and when I asked what they found the issue was they reluctantly told me they had damaged a wire removing the bed. Ironically when my wife started to drive away I noticed a taillight out. No, it wasn't a bulb burned out - it was a damaged connector that they touched. Hard to find good help I guess. Not trying to dispute, and stranger things have happened, but with the parts swappers in some of these shops today, things are not always as they appear.
 
A one amp draw will drain a battery overnight. Does it go down that fast? If not, you don't have a one amp draw. How long are you expecting this vehicle sit unused and then start? I suspect you may be chasing your tail. Two weeks is about all I can expect. Longer than that is a bonus. Six weeks to all winter, no way. I currently have a customer who expects his 89 LeSabre to set unstarted for two months, then fire right off. Check the hood light wire, have had a couple of these trucks chafe the wire and lightly short with the hood closed. Not enough of a short to pop the fuse, but enough to drain battery.
 

A 1 amp draw should not run down a battery over night.
If it does the battery is pretty pathetic.
 
Technicians at dealerships don't get paid to trouble shoot,
especially under warranty. Warranty diag time is .3 of an
hour or less (18 minutes). Even if they are paid $30 per
flatrate hour, that is only $9. How hard would you work on
something for $9?
 
(quoted from post at 21:13:06 03/18/14) A one amp draw won't run it dead, but will pull it down low
enough it may not start the engine.

Yep if everything is not top notch and it is cold
 
When I was with GM, we occasionally had a gal from a local college complain of the battery going down in her car.

Almost without fail, it would turn out that her boyfriend had recently installed an aftermarket sound system. We would decline to work on them 'cause we had no way of knowing what the boyfriend may have done.

That being said, one of my wife's brothers once brought me a late '80's Chevy conversion van with the same problem of the battery draining. I went through the usual trouble shooting, and while under the hood I found the horn disconnected. What had happened was the horn button in the steering wheel broke causing the horn to blow continually. Someone simply unplugged the horn. This, however, still left the horn relay energized which was causing the problem. I fixed the horn button and the problem went away.

Must have been a healthy horn relay to stay energized for several months and then continue to function normally.
 
until you find it........
My 07 GMC with just the normal drains, gives me a lot of trouble
starting in frigid weather when I haven't gone anywhere for a few days. This is normal for me. Once a week runs to town in bad weather.
I started using a battery tender, but getting thru the ice and snow to the hood was a pain.
So, I picked up an adapter for my tender that plugs into the cigarette lighter. Leave the tender on the passenger floor(on a board) and plug it in when I park it. no more problems.
Except I do take some ribbing...
'whatcha think ya got...a diesel?'
 
Glenn, I started a new post about battery draw test. Take a look and see if that helps you find your draw. David
 
We had a compressor once that killed its batteries no matter what was tried. It turns out, a defective oil pressure sensor was not unlatching when the unit was turned off and it was causing a drain in the system by back-feeding through the alternator (it was a really weird setup). Replacing the oil pressure sender cured the problem instantly. May not be applicable in this case, since I doubt there is any power going to the oil pressure sensor in a car when it is shut off.
 
Auto electrical problems can be worse then a locked up engine!
A few weeks ago, I posted a similar problem with my 2001 Ford Ranger.
I worked on it for several weeks and about two weeks ago--Volt Drainage Stopped!! It fixed itself, I guess.
I know this doesn't help but you never know with today's electrical stuff!
 

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