Parasitic battery draw.

wtd

Joined
Jun 25, 2002
Messages
3,339
Location
southwest Mo.
About a month ago, my fiancées 1994 cavalier started killing the battery in about a weeks time. Since the battery was five years old we just thought it had finally went out because it was so dead it wouldn't even charge. We replaced it and about a week later it was dead again, down to 10% charged. I tested the alternator with my tester and then took it to parts store for them to test and it showed it was charging at a high rate, about 15.6 to over 16 volts so we replaced it under the lifetime warranty. A week later the battery is dead again. So now I finally get smart and use my multimeter inline with my negative battery cable and the negative battery post and find that I'm getting a 95 milliamp draw with the interior lights off and door closed. This car also has a switch on the dash to operate the dome lights which was turned off. I start pulling fuses one at a time and find that the CTSY fuse circuit is what is causing the draw. The things that are on this circuit are: Interior lights, Horn, Power Locks, Audible Warning system, remote liftgate release(which this car does not have) and the Check oil light. I thought that it might be either the power locks(since they would click and make noise when you would attach the negative batter cable back on the battery with the door open and the CTSY fuse in) or the Audible Warning system because the key in ignition alarm would still sound after taking out the key with the driver's side door open. Ignition switch was just replaced which also deals with this alarm and the battery still drained down so I don't think it's that. I went to the junkyard and got another Multi function alarm module which is part of the audible warning system since it has a speaker in it and the dinging noise comes from it. I installed it and still the same draw at the battery. I disconnected all of the connections I could find in the driver's side door and the dome light switch in the dash with no results. I disconnected the horn pad and that did nothing. I disconnected a big black connector that is mounted right next to the alarm module and the battery draw went back to normal. This black connector has tons of wires on both sides and I can't really tell where it goes since it's up under the dash on the driver's side. I have not taken the passenger side door panel off to disconnect all of it's connections but I don't have high hopes that it will solve anything. This car also doesn't have the typical door jamb switches for the dome light but rather a door handle activated switch which I don't know how it works because with the door panel off, there are no switches mounted to the back of where the handle attaches and I can't see anything else in the door that would be a door switch. so I'm kind of at a standstill. I'm not the best at diagnosing electrical stuff so what else should I be doing to try and track this issue down? Thanks for any input or advice.
 

gathermewool

Site Donor 2023
Joined
Jan 9, 2009
Messages
9,933
Location
New England
Originally Posted by wtd
I disconnected a big black connector that is mounted right next to the alarm module and the battery draw went back to normal.
Can you elaborate on this?
 
Joined
Jun 11, 2003
Messages
1,081
Location
Hedgesville, WV
It sounds like you have done more than most dealerships. I dont know what it is about older cars and trucks but something causes them to draw more parasitic load. Did you ever notice that the factory installed battery last 6 or 7 years and the replacement might go 4 or 5 and then every one after that only seems to last 2 or 3. It seems to happen on every car I have ever had ( I tend to drive the wheels of of them before replacing) I am going through the same thing with a 03 Ram. When the battery is first connected I get a large draw about 300 ma then after 5 or 10 min it drops to 100 ma then finally after 30 min to 50 ma. If I start with a fully charged battery after 4 days or so its down to 50%. No way a 50 ma draw is draining a 1000 CA battery down in 4 days so something else is turning on and off and drawing it down. I have read that certain EVAP test will kick in if the fuel level is right and the temp is in a certain range and the engine has been warmed up for a spec time before shut down. I have used the disconnect switches but I hate too because of the ECM and learning mode it goes into and I am not crazy about shocking that expensive computer all the time. Like you I know something is going on but darned if I can find it. Now I have a 10 watt solar panel in the window plugged into the aux port when it sits.
 
Joined
Apr 27, 2010
Messages
13,464
Location
Suburban Washington DC
Originally Posted by wtd
I start pulling fuses one at a time and find that the CTSY fuse circuit is what is causing the draw.
You can't rely on pulling fuses on modern cans with multiplexed electronics to diagnose drains. Pulling a fuse on one circuit can awaken a module on different circuit. You need to do a voltage drop test across the fuses.
 
Joined
Sep 13, 2004
Messages
1,904
Location
Canada
On my 1992 Oldsmobile, there was a relay that energized a seat belt tensioner solenoid that tends to go bad after a while and stays in the powered up state. Took me a decade to track it down, but once I unplugged that, magically my battery drain issues went away. A 1994 Cavalier, I can't say it has the same issue, but they're certainly comparatively very simple compared to the modern stuff.
 

wtd

Thread starter
Joined
Jun 25, 2002
Messages
3,339
Location
southwest Mo.
Originally Posted by gathermewool
Originally Posted by wtd
I disconnected a big black connector that is mounted right next to the alarm module and the battery draw went back to normal.
Can you elaborate on this?
This black wiring connector is mounted to the convenience center next to the Alarm module and up past the fuel panel. It probably has 20 wires or more coming out both sides. It is secured together by a bolt. All of the wires are wrapped in that black tape and it looks like it goes up into the dash as well as other directions. I have no idea what those wires power. I only have the basic Haynes and Chilton manuals for this car so it doesn't really tell much and the wiring diagrams are not the best.
 

wtd

Thread starter
Joined
Jun 25, 2002
Messages
3,339
Location
southwest Mo.
Originally Posted by StarCaller
I had the same thing on a 2000 cavalier; ended up putting one of those disconnectors on the battery /
Her dad suggested doing that and is what may happen if I can't figure this out.
 

wtd

Thread starter
Joined
Jun 25, 2002
Messages
3,339
Location
southwest Mo.
Originally Posted by samven
It sounds like you have done more than most dealerships. I dont know what it is about older cars and trucks but something causes them to draw more parasitic load. Did you ever notice that the factory installed battery last 6 or 7 years and the replacement might go 4 or 5 and then every one after that only seems to last 2 or 3. It seems to happen on every car I have ever had ( I tend to drive the wheels of of them before replacing) I am going through the same thing with a 03 Ram. When the battery is first connected I get a large draw about 300 ma then after 5 or 10 min it drops to 100 ma then finally after 30 min to 50 ma. If I start with a fully charged battery after 4 days or so its down to 50%. No way a 50 ma draw is draining a 1000 CA battery down in 4 days so something else is turning on and off and drawing it down. I have read that certain EVAP test will kick in if the fuel level is right and the temp is in a certain range and the engine has been warmed up for a spec time before shut down. I have used the disconnect switches but I hate too because of the ECM and learning mode it goes into and I am not crazy about shocking that expensive computer all the time. Like you I know something is going on but darned if I can find it. Now I have a 10 watt solar panel in the window plugged into the aux port when it sits.
When she got home from work yesterday, I checked the battery and it was 100% charged so I know the alternator was doing it's job. I checked it this morning before she left for work and it was at 25% charged and the battery voltage was at about 11.8 volts. She took my car to work and I messed with hers all day. This car is fairly basic so I'm not sure if other things are turning on during the night and I don't think the ECM goes into any learning mode but I could be wrong. All I know is that it's driving me crazy.
 

wtd

Thread starter
Joined
Jun 25, 2002
Messages
3,339
Location
southwest Mo.
Originally Posted by atikovi
Originally Posted by wtd
I start pulling fuses one at a time and find that the CTSY fuse circuit is what is causing the draw.
You can't rely on pulling fuses on modern cans with multiplexed electronics to diagnose drains. Pulling a fuse on one circuit can awaken a module on different circuit. You need to do a voltage drop test across the fuses.
I'm not exactly sure how to do a voltage drop test on the fuses so I will have to do some research on that.
 

wtd

Thread starter
Joined
Jun 25, 2002
Messages
3,339
Location
southwest Mo.
Originally Posted by pitzel
On my 1992 Oldsmobile, there was a relay that energized a seat belt tensioner solenoid that tends to go bad after a while and stays in the powered up state. Took me a decade to track it down, but once I unplugged that, magically my battery drain issues went away. A 1994 Cavalier, I can't say it has the same issue, but they're certainly comparatively very simple compared to the modern stuff.
The connectors going to the seat belt retractors were one thing that I did not connect inside the door. I'm not sure if it has a seat belt tensioner solenoid. I don't remember seeing anything mentioned in the service manuals about it but I will look again. I will also unplug the retractors and see if that makes a difference. I dread taking off the passenger side door panel since the driver's side was pretty difficult and I ended up breaking some plastic since it's fairly cold out and the plastic is brittle from age.
 

wtd

Thread starter
Joined
Jun 25, 2002
Messages
3,339
Location
southwest Mo.
Originally Posted by FordBroncoVWJeta
I'd just leave the fuse out.
I thought about that but the vehicle speed sensor wiring goes through the alarm module and I didn't know if leaving out the fuse will mess with that. From reading about this alarm module, it's almost like it's the predecessor to the BCM that is in the newer vehicles these days. It controls the power locks, the interior lights, the auto dimming dome light, the power auto lock feature, and the wiring going to the seat belt retractors.
 
Joined
Aug 3, 2017
Messages
2,232
Location
MN
Great job so far, you're farther along than most real mechanic's would be at this point. It reminds me of an old 2000's Stratus I worked on that had all kind of electrical issues due to a shorted ignition cylinder lockout solenoid. That was a fun one to track down... Looking at the wiring diagram, assuming this isn't a convertible or wagon, the following are powered by the CTSY fuse: LF door lock sw RF door lock sw Luggage compartment lamp Dome lamp Instrument cluster Multifunction alarm module Horn relay Door unlock module Given that you already ruled out the alarm module, and the drivers door switch, I would next try the passenger door switch. I know it's a pain. The dome light and luggage light are easy, just look to see if they're on. The horn works, I presume, so that's not a likely culprit. The only things left are the IC and door unlock module. I couldn't actually find any reference to a "door unlock module" in the service info, but I did find reference to an "Automatic Door Lock Relay" that's supposed to be behind either the passenger kickpanel or behind the passenger side of the dash (Behind I/P on Right Shroud is what the manual says). This relay is activated by either the multifunction module OR either door lock switch. It's basically a two in one relay, where one side controls the lock function and one controls unlock. Try unplugging this relay and see what happens. Also, when you find this relay, as another test, which I would do with the multifunction module DISCONNECTED (since you've ruled it out by swapping): with no door lock switch pressed check for voltage on either the black wire, pin F, or the light blue wire, pin A. If you have voltage on either of those with no switch pressed, there's a problem. The switches splice together before the relay, so because you've already tried disconnecting the drivers side switch it would point to either the passenger side or a short to power somewhere. If there's no voltage on either wire, you've got a short somewhere. Just for reference, the multifunction module only controls the lock function, not unlock. So if the problem is on the unlock (black) wire, it can't be the module. The diagrams are very confusing, when I look at the power distribution diagram it's called a "Door Unlock Relay" but everywhere else in the service manual it's called an "Automatic Door Lock Relay". It serves both functions, however the lock side it the only one that the multifunction module has control over. Very weird. Hope that helped a bit! A couple vodka's make it harder to translate diagnostics into words smile *Edit again* If all that fails, you would have to start looking at the things controlled by the multifunction module. The only other outputs I can see on the module are the seatbelt retractors, as mentioned previously. Do all the seat belts work? None are locked up? Another easy check, although you may have already done this.
 
Last edited:
Joined
Jun 9, 2012
Messages
1,016
Location
Reno, NV
Originally Posted by samven
It sounds like you have done more than most dealerships. I dont know what it is about older cars and trucks but something causes them to draw more parasitic load. Did you ever notice that the factory installed battery last 6 or 7 years and the replacement might go 4 or 5 and then every one after that only seems to last 2 or 3. It seems to happen on every car I have ever had ( I tend to drive the wheels of of them before replacing) I am going through the same thing with a 03 Ram. When the battery is first connected I get a large draw about 300 ma then after 5 or 10 min it drops to 100 ma then finally after 30 min to 50 ma. If I start with a fully charged battery after 4 days or so its down to 50%. No way a 50 ma draw is draining a 1000 CA battery down in 4 days so something else is turning on and off and drawing it down. I have read that certain EVAP test will kick in if the fuel level is right and the temp is in a certain range and the engine has been warmed up for a spec time before shut down. I have used the disconnect switches but I hate too because of the ECM and learning mode it goes into and I am not crazy about shocking that expensive computer all the time. Like you I know something is going on but darned if I can find it. Now I have a 10 watt solar panel in the window plugged into the aux port when it sits.
When electrolytic capacitors get old, they often get leaky. That is the most likely cause.
 

wtd

Thread starter
Joined
Jun 25, 2002
Messages
3,339
Location
southwest Mo.
Originally Posted by 14Accent
Great job so far, you're farther along than most real mechanic's would be at this point. It reminds me of an old 2000's Stratus I worked on that had all kind of electrical issues due to a shorted ignition cylinder lockout solenoid. That was a fun one to track down... Looking at the wiring diagram, assuming this isn't a convertible or wagon, the following are powered by the CTSY fuse: LF door lock sw RF door lock sw Luggage compartment lamp Dome lamp Instrument cluster Multifunction alarm module Horn relay Door unlock module Given that you already ruled out the alarm module, and the drivers door switch, I would next try the passenger door switch. I know it's a pain. The dome light and luggage light are easy, just look to see if they're on. The horn works, I presume, so that's not a likely culprit. The only things left are the IC and door unlock module. I couldn't actually find any reference to a "door unlock module" in the service info, but I did find reference to an "Automatic Door Lock Relay" that's supposed to be behind either the passenger kickpanel or behind the passenger side of the dash (Behind I/P on Right Shroud is what the manual says). This relay is activated by either the multifunction module OR either door lock switch. It's basically a two in one relay, where one side controls the lock function and one controls unlock. Try unplugging this relay and see what happens. Also, when you find this relay, as another test, which I would do with the multifunction module DISCONNECTED (since you've ruled it out by swapping): with no door lock switch pressed check for voltage on either the black wire, pin F, or the light blue wire, pin A. If you have voltage on either of those with no switch pressed, there's a problem. The switches splice together before the relay, so because you've already tried disconnecting the drivers side switch it would point to either the passenger side or a short to power somewhere. If there's no voltage on either wire, you've got a short somewhere. Just for reference, the multifunction module only controls the lock function, not unlock. So if the problem is on the unlock (black) wire, it can't be the module. The diagrams are very confusing, when I look at the power distribution diagram it's called a "Door Unlock Relay" but everywhere else in the service manual it's called an "Automatic Door Lock Relay". It serves both functions, however the lock side it the only one that the multifunction module has control over. Very weird. Hope that helped a bit! A couple vodka's make it harder to translate diagnostics into words smile *Edit again* If all that fails, you would have to start looking at the things controlled by the multifunction module. The only other outputs I can see on the module are the seatbelt retractors, as mentioned previously. Do all the seat belts work? None are locked up? Another easy check, although you may have already done this.
Wow, thanks for the detailed reply. This car is a two door coupe. None of the inside lights are on. It has a separate switch on the dash to turn the dome light off. The glove box light is removed since the door is warped and wont fully contact the switch. The trunk light does go out when you put the trunk lid down. The horn does work. All of the seat belts do work. The automatic door unlock seems to work and there doesn't seem to be any change in how they work since this issue first started about a month ago. When I disconnected the driver's side door lock/unlock switch I also disconnected the passenger side one as well since you can just pop those out of the door panel without removing the panel and with both disconnected there was no change in the readings. The black harness connector that I referenced above that I disconnected that caused the multimeter reading to go back to normal was the I/P harness connector which is located right next to the convenience center and the Multifunction alarm module. I was thinking of trying to use a jumper wire to cross both sides of the connector on each pin to see which one shows the high draw to try to pinpoint which wire is causing the issue and then trying to figure out what that wire goes to. I'm not sure how much I will get done today since it's close to freezing out and raining and I'm super sore from being under the dash of several cars yesterday trying to find and then remove the alarm module. I had to get the module out of a 94 Buick Century which the module in it is mounted in a very difficult place to access. The car only had 90,000 miles on it so I was pretty confident that the module would still be good plus the car had been wrecked which ended it's life. Thanks again for all of your help.
 

wtd

Thread starter
Joined
Jun 25, 2002
Messages
3,339
Location
southwest Mo.
Well, I've narrowed the problem down a little bit. I used a jumper wire between the two halves of the I/P connector until I found the corresponding pin and socket that showed a draw. It was F2 on the connector diagram. I don't know what circuit 40 is yet or what those cell numbers mean. The pin side of the connector has two orange wires coming out of the pin, one a larger darker wire and one a smaller lighter color. On the socket side of the connector, there is just one smaller lighter orange wire coming out the back of the socket that looks to be the same size and color of the smaller lighter orange color wire on the pin side of the connector. The 0.93 reading on the meter is with the jumper connected between the two F2 pins and sockets of the connector. The 0.01 is the reading I get with either the connector unplugged or with the CTSY fuse removed. For this test, the CTSY fuse was installed. On the diagram, the top connector picture is the pin side of the connector. If anyone can tell me what circuit 40 is or what those cell numbers mean on this diagram, I would appreciate it. [Linked Image from i.imgur.com] [Linked Image from i.imgur.com] [Linked Image from i.imgur.com] [Linked Image from i.imgur.com]
 

wtd

Thread starter
Joined
Jun 25, 2002
Messages
3,339
Location
southwest Mo.
Well, looking more through the service manual(This is a factory service manual for a 1992 Cavalier that I had that I finally found. It's probably not exact for a 94 but most things are probably the same) circuit 40 and solid orange wires seem to mean a fused battery source so I don't think this really helps me figure out what is causing the draw on the battery. I did see that on the diagram for the convenience center and the A position for the alarm module that the wire is orange and it is on circuit 40. I just need to find out what all is attached to circuit 40 and maybe can narrow it down from there.
 

wtd

Thread starter
Joined
Jun 25, 2002
Messages
3,339
Location
southwest Mo.
Well, I believe I fixed the issue but not after taking out the instrument panel and taking down the dome light to see if it was shorting out. I started looking at the wiring diagram that came off of the CTSY fuse and it did show that it was circuit 40 and that the wiring was orange. It went to the alarm module, the instrument panel, the horn relay, the dome and trunk light, and the two door handle switches that activate the dome light. After removing the horn relay and instrument cluster and nothing changing, I decided to check the trunk light again before trying to find and tear into the door handle switches. A few weeks ago I noticed that the trunk light was burned out. I put a new bulb in it and didn't think anything of it. The light did go out when I lowered the trunk lid so I assumed it was working correctly. Today when I went to check to see if it was on for some reason, the bulb did not come on even though it didn't look burned out. I disconnected the harness in the trunk and then hooked my meter up again and now there was no draw showing. I examined the wiring and the socket to see if there was any damage or burned look at the socket but didn't see anything. The only thing that I can figure is that maybe the mercury switch that turns on the light when you raise the lid somehow malfunctioned and was causing a draw. I guess I went the long way around to finally figure this out. I hope it's fixed. I will check the battery voltage in the morning to see if it stayed charged. Thanks for all of the ideas and tips.
 
Top