92 Buick LeSabre Electrical Problem

Apologies for creating a separate thread for this topic, there was a similar thread for electrical issues from 92's, but the symptoms from my car seem different than those in the other post.

A friend and I placed a meter between the neutral wire and the negative terminal of my battery while the car wasn't running and everything was off. There was a drain in excess of 500 mA.We first tried to figure out what system had something wrong with it by yanking out each fuse and relay from the fuse box above the pedals and the fuse/relay center mounted on the firewall under the hood. The drain wasn't interrupted by removing any fuse or relay. We also checked the alternator and starter, and neither were the source of the drain. This was also confirmed when we removed the positive feed for them from the battery. This means that the drain must be from somewhere in the circuit that feeds the relay/fuse center mounted to the firewall, which basically covers much of the car's systems. We checked the feed line to the fuse/relay center visually and didn't observe any frays etc. We checked to see that the trunk light wasn't stuck on continuously, and even tried another battery, to no avail :banghead:

Here are the symptoms that I've observed that caused me to start seriously looking for what might be wrong as I described above :

I've found my car battery dead on several occasions. This has been going on intermittently for several months. I initially thought it was because I was a dummy and left my headlights on, but apparently not :) . On several, if not all, occasions when I unsuccessfully attempted to turn the engine over, I heard a clicking noise from the glovebox area, and the windshield defrost button was on, even though I always leave the heating system with the off button toggled before turning off the car.

Approximately 3-4 weeks ago I got in the car, and upon shutting the door the overhead dome light and interior floor lights would not shut off no matter what switch I tried to flip. I remedied the problem by replacing a 15 amp fuse in the box above the pedals. The blown fuse was in the slot for the radio, ip, heating, etc (don't remember everything exactly off the top of my head)

About a week ago my cruise control stopped working. Darn it! I loved my cruise control!

Here are some things that I've been wondering about:

Is there another fusebox or other obvious things that I should be checking?
Is there a better way to check and see if relays are functioning properly?
Can a dealer or other mechanic somehow hook up the car to a computer so that they can isolate what system or circuit is malfunctioning, to at least guide me to look at the right area?

Any suggestions as to what to do next or what resources may be of use to me would be GREATLY appreciated!

Thank you!

Wow, something is really crashing offline here, sounds like there is a pretty major problem bringing this car down. I have the shop manuals for the 1992 LeSabre from GM because I used to own one. You've given me a lot of interesting tid bits here on this problem, so I'll take a look for you in my manuals and see if I can't help you narrow this down. For starters, here is some food for thought

1. All cars have what is called "parasitic drain", to some extent almost all production cars experience some electrical drain even when they are turned off and locked up, the vast amounts of electrical components on a modern vehicle munch away at the battery with time. The problem is that I am not sure if my manual for the 1992 gives any sort of typical drain on this vehicle. Now I know there is a good chance you do have some sort of excessive drain on this car, but I am not sure if the 500 ma is significant or not. Remember that if you had the hood open there is a good chance that the hood lamp may have been on, any lights or anything at all that was turned on when you tested this battery would have caused an increased drain. 500ma could probably be explained with an automotive bulb or two.

2. There is a second fuse box under the passenger side dash board, when you stick your head up under the dash on the passenger side you'll see a big black plastic panel with a light bulb in it, this is the panel that covers the "brains" of the vehicle. The computer, air bag module, and secondary fuse/relay box are just a few of the goodies that you'll find in there. Then when you head back under the hood of your car, there is another black plastic panel that runs along the firewall just under the winder, but on the engine compartment side of the hood gasket back there. You'll see a bunch wires headed up into this panel, and one huge fat cable bunle that goes through the panel. This whole plastic piece is just like the one under your passenger side dash, its simply a cover that reveals a huge "maxi" fuse bus when you remove it. These fuses and relays deal with currents in the 60 amp range, massive amounts of power from the battery are managed by the circuits that you find under this panel. These fuses and circuits feed those that you find in the fuse box near your pedals on the floor, power is then distributed to the fuses under the passenger side dash area.

3. It is much easier to diagnose parasitic drains by playing with the circuits under the hood. Try following the positive battery cable up under that panel mounted against the firewall, it connects to a terminal on that big fuse block i was talking about. To start out, place your meter between the battery terminals like you were before, this time while you have your meter on those terminals, remove the other end of that cable at the fuse block on the firewall. Watch your drain and see if it goes away when you do this, that will just confirm that you don't have a problem with one of the big time components or cables in the primary power system under the hood (battery, alternator, starter). If the drain goes away when you pull the terminal off at the fuse block, you konw that the drain is originating in one of the circuits that is fed from that fuse block, so you can start pulling those huge maxi fuses until it goes away or drops significantly again. You have to sort of work your way down the line by slowly trickling through the various fuses and relays until you narrow it down to a few suspect components. This is a very tetious process, it helps to have someone watching the meter while you do it, but if you just keep reminding yourself that literally anything that can possible short out is supplied by one of those fuses under the hood, the whole process makes more sense.

Welp, while you check out some of this information, i'll check a few things in my 92' electrical service manual from GM and see if I can point you in the right direction, but frankly working your way down those fuses will probably be faster than trying to pinpoint the problem from the manual.

Wow, something is really crashing offline here, sounds like there is a pretty major problem bringing this car down. I have the shop manuals for the 1992 LeSabre from GM because I used to own one. You've given me a lot of interesting tid bits here on this problem, so I'll take a look for you in my manuals and see if I can't help you narrow this down. For starters, here is some food for thought

1. All cars have what is called "parasitic drain", to some extent almost all production cars experience some electrical drain even when they are turned off and locked up, the vast amounts of electrical components on a modern vehicle munch away at the battery with time. The problem is that I am not sure if my manual for the 1992 gives any sort of typical drain on this vehicle. Now I know there is a good chance you do have some sort of excessive drain on this car, but I am not sure if the 500 ma is significant or not. Remember that if you had the hood open there is a good chance that the hood lamp may have been on, any lights or anything at all that was turned on when you tested this battery would have caused an increased drain. 500ma could probably be explained with an automotive bulb or two.

2. There is a second fuse box under the passenger side dash board, when you stick your head up under the dash on the passenger side you'll see a big black plastic panel with a light bulb in it, this is the panel that covers the "brains" of the vehicle. The computer, air bag module, and secondary fuse/relay box are just a few of the goodies that you'll find in there. Then when you head back under the hood of your car, there is another black plastic panel that runs along the firewall just under the winder, but on the engine compartment side of the hood gasket back there. You'll see a bunch wires headed up into this panel, and one huge fat cable bunle that goes through the panel. This whole plastic piece is just like the one under your passenger side dash, its simply a cover that reveals a huge "maxi" fuse bus when you remove it. These fuses and relays deal with currents in the 60 amp range, massive amounts of power from the battery are managed by the circuits that you find under this panel. These fuses and circuits feed those that you find in the fuse box near your pedals on the floor, power is then distributed to the fuses under the passenger side dash area.

3. It is much easier to diagnose parasitic drains by playing with the circuits under the hood. Try following the positive battery cable up under that panel mounted against the firewall, it connects to a terminal on that big fuse block i was talking about. To start out, place your meter between the battery terminals like you were before, this time while you have your meter on those terminals, remove the other end of that cable at the fuse block on the firewall. Watch your drain and see if it goes away when you do this, that will just confirm that you don't have a problem with one of the big time components or cables in the primary power system under the hood (battery, alternator, starter). If the drain goes away when you pull the terminal off at the fuse block, you konw that the drain is originating in one of the circuits that is fed from that fuse block, so you can start pulling those huge maxi fuses until it goes away or drops significantly again. You have to sort of work your way down the line by slowly trickling through the various fuses and relays until you narrow it down to a few suspect components. This is a very tetious process, it helps to have someone watching the meter while you do it, but if you just keep reminding yourself that literally anything that can possible short out is supplied by one of those fuses under the hood, the whole process makes more sense.

Welp, while you check out some of this information, i'll check a few things in my 92' electrical service manual from GM and see if I can point you in the right direction, but frankly working your way down those fuses will probably be faster than trying to pinpoint the problem from the manual.

The level control height sensor is supplied with constant power. Try disconnecting that.

Yeah, but not all of these cars had "air suspension" with the level control sensor, in fact most didn't in 92'. But I agree that if you have the level control and air suspension package, you can try pulling the plug on the sensor. Another thing I thought of while reading the manual is that the power antenna on these cars can be a trouble spot for electrical drain. I remember when my 92' started getting old I would have to go outside after turning off the car and push the antenna down manually to make the motor stop running, it would get jammed in the up position and the motor would run constantly to try and retract it. However, the only sure way to narrow it down without grabbing at straws is to work your way through those fuses, there are only 8 or so under the hood, so it isn't that big of a deal to pull each one out and watch the drain on the meter, this will also tell you if it's a problem with the secondary electrical circuits, or the primary charging/starting circuits under the hood. If the drain stays constant even with that terminal removed from the fuse block under the hood, the problem has to be with the most simple wiring under the hood, because all power except that which is distributed between the starter, battery, and alternator travels through those 8 or so fuses.