electrical problem

I have an 86' Brougham and when ever you use the left rear window switch (the switch on the main set for the driver's use) ALL electric cuts out on the car. We just checked it again after cleaning the battery post. We started the car and moved the switch and the car quit along with everything else, same with the car off. What could be wrong? Thanks for any help.

anyone have any ideas? it's gotten worse lately. The other night my dad tried taking it to work and as soon as he turned the headlights on, the car instantly died. He tried it 3-4 times with the same results, so he just took our truck. I went out later and no lights worked (interior or exterior), then out of no where, everything turned on and worked fine. This afternoon we tried it again and everything cut out like before, but never turned back on. The window switch works fine now which is weird because now nothing else is. Right now we are just gonna buy a new battery and terminal screws (negative was shot and battery not the greatest). Anyone have any ideas? Thanks


P.S. My chevy beretta does the same thing.

anyone have any ideas? it's gotten worse lately. The other night my dad tried taking it to work and as soon as he turned the headlights on, the car instantly died. He tried it 3-4 times with the same results, so he just took our truck. I went out later and no lights worked (interior or exterior), then out of no where, everything turned on and worked fine. This afternoon we tried it again and everything cut out like before, but never turned back on. The window switch works fine now which is weird because now nothing else is. Right now we are just gonna buy a new battery and terminal screws (negative was shot and battery not the greatest). Anyone have any ideas? Thanks


P.S. My chevy beretta does the same thing.

Well hell, I would suspect either grounds or a fusible link somewhere. I don't really know where to start aside from suggesting that you pore over your electrical system with a fine-tooth comb. One possibility might be where the wiring harness passes through the firewall into the car - there is one bolt (7-mm) that attaches this (it's on the firewall underneath and behind the windshield washer fluid tank) to the fuse block on the other side of the firewall. If this bolt comes loose, lots of weird stuff can happen - including the problems you are encountering.

Thanks for the reply. I thought it was bad ground off the battery first because the negative hookup was shot and pretty damn loose. We got the new battery and new screws and I tighened them up good, but some problem, so I ruled that out. i'll have to check that bolt out today. Would the bolt be on top of the harness or under it? Thanks again

Loose connections are BAD. Now, you don't need to make them super tight, especially on something soft with lead (like battery terminals), but being tight assures a good electrical connection. If they are loose, they can cause an intermittent failure or things to not work. This is because a loose electrical connection cause high or very high resistance. This resistance is just like adding a resistor in series with the device. Now, electricans will know that loads (anything with resistance, inductance, or capacitance is a load) in series will cause a voltage drop over each load proportional to the resistance (higher resistance, higher voltage drop). If the loose connection has high enough resistance, you will not have enough of a voltage drop over the load to make it work because total voltage drops in a circuit must equal the voltage applied (12+ volts from battery/alternator). Hense, the devices in your car are designed to work with 12 volts applied minus a very slight voltage drop through the wiring (remember, anything with resistance will cause a voltage drop). If you have a good electrical connection (less than 1 ohm), the drop will be almost no-existant (a couple thousands of a volt or 1/1000 volt).

What about the small ground wire that branches off the main ground wire and connects to the body. All the power died in the parts wagon I bought a year ago while I was trying to drive it home, and all I did was loosen and retighten the bolt and it was fine.

seems pretty easy to try so ill check it out today when I get some time, thanks

By loosening and retightening the bolt, you probably removed some oxidation on your connection. Oxidation is a poor conductor (because it is not pure metal anymore) and that is why it is offen recommended to clean a rusty ground. That extra resistance caused by the oxidation is the same as having a loose connection. Remember, the higher the resistance, the higher the voltage drop (and you connection is not where you want your voltage drop to be, you want to apply as much voltage on the load as possible).

well, I got a new battery, new terminal bolts, redid that ground wire, cleaned the power wire on the starter (the one that comes from the battery) and now luck. Today I took the harness off from the light switch itself and it didn't have any power there (with and without the ignition on). So I ran a wire from a power source to that harness where the headlight wire is and they turned on. I also ran a wire from a power source to the power wire on the harness and then the interior lights come on like they are supposed to do, but if you unhook the power (they stay on themselves after this) source from it and shut the door, next time you open it, everythings off again. Think the headlight switch could be going bad? or still a wiring problem? Thanks

Since your power windows and headlights are relatively big load draws on the system, I agree with the others that there is a bad connection or dead short somewhere. Go over the under-dash fuseblock really well. Pull the biggest main fuses first and see if they are loose, cracked up the middle or partially blown. Then go to the smaller ones as well.

Your local library might have a body/chassis manual for your car which will show you where all the fusible links are, you should also be able to trace the headlight and power window circuits to see where they are common.

Do you have a good auto-electrical shop close by? They could probably fix it really quickly rather than going through the trial and error method.

Bob

The thing that I think is weird is, one night I took out the window switches, but didn't do anything to them, just pulled em out and they now work good as new. I think it's a short like you guys say. We had a cousin (a mechanic) look it over, he checked the fuses/ block and it all checked out that I know of. He said he's gonna call his uncle who works at a shop/ dealer, so if that doesn't work, i'll take your advice and have a shop look it over. Thanks for all the help so far guys and hopefully i'll have this caprice back up and running again soon.

The thing that I think is weird is, one night I took out the window switches, but didn't do anything to them, just pulled em out and they now work good as new. I think it's a short like you guys say. We had a cousin (a mechanic) look it over, he checked the fuses/ block and it all checked out that I know of. He said he's gonna call his uncle who works at a shop/ dealer, so if that doesn't work, i'll take your advice and have a shop look it over. Thanks for all the help so far guys and hopefully i'll have this caprice back up and running again soon.

Did you ever check that bolt I was talking about? It's in the center of the wiring harness "plug", which plugs into the fusebox on the engine side of the firewall, underneath the W/S washer tank. Most of the car's wiring passes through that block.

FWIW, if it isn't starting a fire, it's not a "short" - It's an "open" circuit. A short is a condition where all power is shunted (like connecting a big jumper cable right across the battery or power source). An open circuit is caused by high resistance or the lack of continuty (as in a poor connection, cut wire, or unplugged connector). A true short will take out a fuse, fusible link, melt wires, or burn your car to the ground, whichever happens first.

well sorry about that then, I don't know much at all about electrical, wiring, etc. Would I have to unplug the harness that goes into the box to reach the bolt? or just look under the harness?

Did you ever check that bolt I was talking about? It's in the center of the wiring harness "plug"

By this, I mean the bolt is used to hold the plug to the fusebox. This means that if the bolt is loose, there won't be proper connections (many opens) and therefore you'll have trouble.

Ok, I looked at the spot you told me about. I saw two big plugs, plugged into a box on the firewall like you said. I also saw a nut or bolt in between the two plugs. I tried moving the box to see if it was loose, it had a little bit of play to it. Is that what you meant? or am I still on the wrong track?

Ok, I looked at the spot you told me about. I saw two big plugs, plugged into a box on the firewall like you said. I also saw a nut or bolt in between the two plugs. I tried moving the box to see if it was loose, it had a little bit of play to it. Is that what you meant? or am I still on the wrong track?

That's what I meant.

FWIW, if it isn't starting a fire, it's not a "short" - It's an "open" circuit. A short is a condition where all power is shunted (like connecting a big jumper cable right across the battery or power source). An open circuit is caused by high resistance or the lack of continuty (as in a poor connection, cut wire, or unplugged connector). A true short will take out a fuse, fusible link, melt wires, or burn your car to the ground, whichever happens first.
I agree if your car is not on fire or your battery is staying charged you don't have a short or a dead ground. It sounds like the juice just ain't gettin to all the stuff and then when it gets to going it makes a turn and goes some where else. Another question has this car sat for a period of time? If so you may have some rust in a few connections.

Ok, I looked at the spot you told me about. I saw two big plugs, plugged into a box on the firewall like you said. I also saw a nut or bolt in between the two plugs. I tried moving the box to see if it was loose, it had a little bit of play to it. Is that what you meant? or am I still on the wrong track?
Take that loose spray it with contact cleaner or WD-40 and put it back together. Look there to see if anything is melted.

well, before we bought it, it wasn't a primary vehicle, so it wasn't used much, but was still driven every now and then. I know the previous owner and he told me the other day that it could be a fusible link on or around or w/e the starter. He said it went on him before. As for checking these plugs, can I just unplug them? or are you not supposed to? It's been raining and a bit cold around lately, along with looking into problems on my dads truck, so I havn't been able to look at it.

well, before we bought it, it wasn't a primary vehicle, so it wasn't used much, but was still driven every now and then. I know the previous owner and he told me the other day that it could be a fusible link on or around or w/e the starter. He said it went on him before. As for checking these plugs, can I just unplug them? or are you not supposed to? It's been raining and a bit cold around lately, along with looking into problems on my dads truck, so I havn't been able to look at it.
If it's the fusible link going to the starter that explains a lot of the no power. You need to find it cut it out and replace it with the same amp. As for the main fuse block plug just take out the bolt or bolts unplug check or just sung it a bit and tighten the bolt(s) a little and go from there.

Hey guys... I'm currently having the same problem!!! 1992 caprice 305.. as follows:

When I first got the car, it wasnt running. We tried everything electrical under the hood until my uncle shook the ECM and suddenly it started. He said not to worry about it, that it was just loose. Things were fine for MONTHS until:

Last week I disconnected the battery to work inside the door panel and after that, I kept having this wierd problem where when I turn the key, the power is lost and nothing works. Disconnect and reconnect the battery and all is fine... I thought it was a loose connection to the battery until:

The sh* really hit the fan yesterday when I lost power while driving... No steering, no braking, Nothing.. Just me and a metal newspaper stand and a whole lotta blue paint on my pretty white caprice afterwards... :shakehead

Just my :2cents: but I'm guessing we're experiencing the same thing.. it cut off while driving as i slid the setting from Hot to Cold on the comfort settings.

Can anybody give me some pointers as to where to start with the ECM/under-dash wiring??? I'm lost on even where to start as to getting to the ECM & etc to accurately check the connections... IF the ecm is malfunctioning, I can replace it for $90 but either way it goes I need to get to it.

Definitely sounds like a loose or corroded connection, possibly the ground for the ECM. As far as the effect of sliding the climate control from hot to cold causing it to die, I'm a little puzzled myself.

The ECM has nothing whatsoever to do with the power windows.

I still think it has either to do with a bad or marginal fusible link at the solenoid, or the fuseblock/underhood harness interface.

Hey guys... I'm currently having the same problem!!! 1992 caprice 305.. as follows:

When I first got the car, it wasnt running. We tried everything electrical under the hood until my uncle shook the ECM and suddenly it started. He said not to worry about it, that it was just loose. Things were fine for MONTHS until:

Last week I disconnected the battery to work inside the door panel and after that, I kept having this wierd problem where when I turn the key, the power is lost and nothing works. Disconnect and reconnect the battery and all is fine... I thought it was a loose connection to the battery until:

The sh* really hit the fan yesterday when I lost power while driving... No steering, no braking, Nothing.. Just me and a metal newspaper stand and a whole lotta blue paint on my pretty white caprice afterwards... :shakehead

Just my :2cents: but I'm guessing we're experiencing the same thing.. it cut off while driving as i slid the setting from Hot to Cold on the comfort settings.

Can anybody give me some pointers as to where to start with the ECM/under-dash wiring??? I'm lost on even where to start as to getting to the ECM & etc to accurately check the connections... IF the ecm is malfunctioning, I can replace it for $90 but either way it goes I need to get to it.
Did you tighten down the ECM after your uncle found it loose?

Did you tighten down the ECM after your uncle found it loose?

I dont really know how to get to it!! I think I've found the bolts... 2 of them on the engine side of the firewall right? Behind the wheel well/wiper fluid tank? I'll try to get to them tomorrow.. I'm paying a guy $35 to help me install fresh battery cables (Advance Auto's OEM Special for $20) $55 total But this is cheaper than the $300 for the positive cable only that GM was going to charge...

I'd do it all myself but I'm a computer guy.. Not a car guy! I'm paying him to sort of help me through it really more than anything so that I dont screw anything up. I want to learn though, that's why I'm here!!!

Also: Dont know if this means anything other than to change the batt. cables, but, the battery tested bad within the 45 second test while in the car.. it tested GOOD while out of the car though... Thinking I should check the ignition system as well.. the alternator is new/rebuilt as of a year ago I think... the starter may be an issue I guess.. I'll clean all connections to the battery cables while connecting them..

Use an ohm meter, and check ground between the body frame, engine and battery negative terminal. It should be zero ohms, or pretty close to it.If it isn't, put a ground strap or heavy gage wire (Min 12 Ga.) from there, to the others, or directly to the negative terminal of the batery. That should take care of your problem.

HI, I am just reading this post for first time. I will admit i only skimmed over all the replies quick. Is there still a problem with this car? I have changed entire dash or engine harnesses in these cars when installing power options or converting from 4.3 to 5.0 for Saudi export. That bolt at back of fuse box is very very important. It is dead center of the wires. You will want to remove the washer reservoir first.

Your cars body, engine, (including starter and battery), and underhood body harness for wipers and headlights all junction together here in three seperate connectors. This bolt is CRITICAL as well as connections. Also keep in mind the master power window switch is the brain to the whole power window system on any full size GM car of this era. It also incorporates the relay and has a main ignition and ground circuit going in. IT is VERY easy to isolate problems from this system. Dead center towards the top of your fuse box will be a thick pink wire. (thicker of the two sizes you will notice) This can be unplugged about 6 inches back from fuse box OR removing the METAL 30 amp circuit breaker that looks like a fuse. Any window problems at all and this is DESIGNED to get hot and disable the power windows on the car until it cools back down and makes contact again. ALso note the same cicuit breaker with heavy orange wire in the lower right, will disable your power seat and door locks. IF either of these breakers were to fail and not break the circuit, it ultametely will lead to a burnt fuseable link of not car fire. Some early warning signs would be the entire electrical system going haywire and the engine shutting off. Hope this information is useful to anyone with power accessory troubles. If too late to fix this problem, maybe useful to other problems currently or later down the road. I see the thread is getting old. Thanks DAN

Hi again, I apoligize that I just discovered the second page of this thread before i responded. It is not common for these cars to be popping fuseable links. It takes a dead short to do that in a major circuit that a fuse would not protect. These are not considered a wear item as other parts of the electrical system are.

Regardless of you having a 4.3 or 5.0 engine in the 1986 Brougham, check the red wires at back of alternator. Mainly makeing sure the bolt on wire is tight. Wiggle it around and see if you get any reaction from the car. This wire feeds back down to the starter and if there were ever a dead short from it getting too close to engine block, you will WANT it to blow a fuseable link. Otherwise it would be like having jumper cables hooked up backwards and something better melt fast before the fire comes, HA! I suggest having headlights on or something so that if you do get a short, you notice sooner instead of relying on sparks under the engine. IF you have any suspicions whatsover of this red wire from alternator to the starter..disconnect your battery immdediately. As long as you cut this wire off at both ends, you could run a new one with a fuseable link, straight to the battery instead. It does not HAVE to go through the harness and down the back of the engine as the factory designed it.

Also note that the headlight switch on these cars does not have a fuse. There is a built in circuit breaker inside the switch. Should something go wrong, a fuseable link WOULD blow. Also a problem in the ignition switch could blow fuseable links and shut car off without warning. Not common to go bad, but if this car by any chance ever had aftermarket alarms or starters installed, as many Caprice cars in larger cities DO, that opens a whole new can of worms. I apoligize if i do not understand the problem correctly and giving repetitive or non-applicable advise to this problem.

As far as the guy having the problem with the 1992. I am stumped on that one. The HOT cold lever is just a freak coincidence UNLESS some other aftermarket wire is getting caught behind glove box where the temp CABLE opererates. There is absultely nothing electrical involved with makeing any Caprice go from hot to cold. Its just a mechanical door that gets moved inside the heater box. DAN

Yeah, I'm wondering if the guy got his problem fixed. It has to be something VERY basic and obvious, once he finds it, lol. Any fusible link that I've ever had blow on me was a show stopper, not something intermittent.

Once I isolate a potentially bad one, I give each end of the link a tug and it will come apart if it is blown.

Bob

Hey guys. wow its been awhile, sorry for not checking in but I thought this ended awhile ago. Its nice to see this much help though. I honestly havn't taken much time into the car, due to the fact that i've been working on my car and the caprice is more of my dads (secondary vehicle). As of today, the power windows work fine now, but I havn't put enough time into the light problem to solve it, so it still exsists. I located that bolt you told me about on the main harness, but I couldn't get my wrench in there at it and I didn't wanna have something break, because thats the luck I usually have. Should the wrench fit in there without a fight? also, would anyone happen to know the size of the bolt? this may sound dumb, but could the light switch cause this no lights problem? my car (88' beretta) has the same problem, and a friend ran a wire from the fusebox to the headlight wires and they turned on, so he told me my headlight switch is probably dead. Oh, I also checked for the fusible link, is that a red wire with a bigger black section on it? cause if thats it, it doesn't look broke. Anyway, tomorrow i'll deffinitly put time into looking the car over. I'll post back after that. Thanks for all the help so far from everyone.