Joffroi

I was driving my car this weekend and ran into an electrical problem I was hoping someone could help with. Its a little odd of a situation so I'll do my best to explain every below. Any help or ideas on what could have caused the power failure and how I can make sure it doesn't happen again would be greatly appreciated.

About the car: 1972 Cutlass Supreme. MSD Ignition. After market sound system (nice head unit, subs, speakers), electric fan and fuel pump.

What happened: I was driving my car in great 70 degree sunny weather. Only drove about about 10 minutes before heading home when suddenly my stereo stops and my head unit powers off. I turn it back on. 2 seconds later, my car just shuts off (all electronics and motor). Luckily I was only a half mile from my house and was able to roll into a cul de sac. I went ahead and tried to jump my car just in case my alternator went out. Nothing happened. Even still plugged to another battery, none of my electrical turned on.

I went ahead and called AAA to get my car towed the half mile to my house. About 20 minutes later, it was time to ease the car off the tow truck into my garage. Oddly enough, this time when I turned the key a little to put the car in neutral, the electric radiator fan I have kicked on.

After the tow truck drive drove away, I went ahead and tried to start the car. Started right up! Only thing that didn't turn on was the head unit of the sound system. I then just tried taking off the head unit and put it back on. Hit the power button and just like that, everything was working again.

Solution ?
Where should I look to hopefully fix whatever problem I had and what would case a car to just lose power on minute, but then regain everything about 30 minutes later. Faulty ground wire?

MDchanic

Could be a bad ground, like the strap from the engine to the body, or a bad connection in one of the heavy cables to the battery.

Where is the stereo equipment hooked up? To the battery, to the horn relay, or somewhere else? Photos might help, since you've got custom gear.

- Eric

Joffroi

I was suggested to check the ground, which I'll do as soon as I get home and have the time. Its hooked to the battery.

The attached picture (also below) is the only one I currently have. I know it doesn't really provide that much input to what is going on. I'll try to snap more tonight. I'm just puzzled on what would kill EVERYTHING electronic, but then work later. I feel like it has to be one of the connections to a major wire (like the ground) as you said.

t92R0.jpg

MDchanic

It's usually either the (-) or the (+) terminal at the battery.

If the terminals aren't tight, and a little bit of corrosion builds up between the clamp and the post, you can end up with a very narrow area of contact, which can disappear when it shifts position or gets hot.

Other interfaces, such as wire to terminal, as also possible.

I'd pull the battery cables, inspect everything carefully, clean all mating surfaces with a terminal cleaner brush until shiny, coat everything with Vaseline, and reinstall.

- Eric

gearheads78

Battery positive cable , ground or a conntection from them. Start jiggling cables and see it you can make it not start again.

Lady72nRob71

Or tug GENTLY on the wires to see if one of them comes apart from its connector. I have seen this before.

Rickman48

Had the exact same problem while I was working on a S-10 Blazer!!
Someone had used a crimp connector on the small wire from the negative battery cable to the core support, and it corroded loose!
Thankfully, left enough wire to install the right connector, and done!

oldcutlass

I don't understand how a battery cable will cause the car to turn off when its already running??? When the car starts it basically runs off the alternator. I would think there is something amiss in the run circuit, and or charging system.

Joffroi

Lets say there is an issue with the alternator... if that crapped out, shouldn't have kicked to my battery and then drained that dead?

Rickman48

When you have no ground, the electricity can't complete it's circuit! Anywhere!

MDchanic

If the ground or the positive connection from the engine to the rest of the car were interrupted (ie: ground strap), you'd lose power.

- Eric

Joffroi

Well, my situation changed for the worse. I was looking around my battery area for a lose cord. Low and behold, I found about a 1 foot long cord connected to the fender to nothing. I suspected that it was important and felt I needed to test to see what still worked on my car. Of course now nothing does. Back to the state of no power anywhere. Maybe vibrations unscrewed this cord while driving? Its only about a foot long and I can't find any place it should go. Since its grounded into the frame, I feel it needs to go somewhere hot. Being pretty stupid, I touched it to the hot end of the battery. The battery still has a charge. This is tough for me because my previous cutlasses were original and very simple to follow everything. This is a litter different. For starters, looks like the ground wire is read and the hot wire going to the starter is black.

Below are pictures of the mystery cord.
I tried to label where I thought everything else went. The red circle is the mystery cord.
IwUuG.jpg
Another angle. The end of the connection is a circle to go around a bolt or screw. So that tells me a screw felt out somewhere.
HcR55.jpg
yJ0QZ.jpg

My alternator. The thicker wire (which I suspects is the ground, seems to loop around my engine bay and eventually go to the hot end of the battery. Maybe I'm just going crazy.
Lbfhv.jpg
Xpo7y.jpg

If any more pictures would help diagnose this, please let me know. Its always sad having a dead cutlass in the garage.

MDchanic

Okay, you've got a bunch of wires there, but it's not that complicated.

Your Positive Terminal is on the Left in this picture.

• Wire with yellow collar: Power to sound system.
• Pair of Blue wires: Go to the two relays, probably for the headlights
  (do you have fancy high-output headlights?)
• Big Black wire with silver terminal: Positive from Alternator.
  The Alternator DOES NOT have a negative or Ground wire - it grounds to the engine.
• Big Black wire with Copper terminal: Positive to Starter

Your Negative terminal is to the Right.

• Red wire is Ground to the engine block for the starter.
• Small Black wire that goes off to the side of the battery is probably a sound system ground, to reduce interference.
• Dirty White wire with Red collar (from fender) is supposed to connect to that terminal, too, probably to the same connector that the small Black wire is connected to.

The white wire being disconnected could cause this problem.

This is an object lesson on what I always say:
SOLDER EVERYTHING. PERIOD.

'Nuff said.

- Eric

Rickman48

P.S. - That's the GROUND wire, recently described!!

Texascarnut

And if jacking with the wiring doesn't correct it, check the MSD ignition system for diodes that are crapping out. This whole thing sounds much like the problem often suffered by the Ford ignition system of the 1970s when the ignition control module began biting the dust. Sudden engine shutdown that would sometimes be corrected for a few minutes by allowing the ignition control module to cool down for half an hour or so. Solution, replace the control module. I think you may find the same.

stellar

I agree with this except for the Nuff said. I suspect there are other bad ground connections as well. Possibly even the main ground to the block being connected over Paint or corrosion. Since there does not look to be much corrosion on this car I would check all grounds for good connections to metal without paint inbetween. Also look close for other wires that may have become overheated or melted. The current that should have been going thru this wire had to be going thru somewhere else before the circuit opened to cause the failure. I have seen throttle cables welded inside the cable metal shielding because of bad grounds as well as fuel lines arcing and causing fires. Please check the ground circuit good. This side of the circuit is every bit as important as the positive side.

Highwayman

X2 on the solder.


A stranded wire with a crimp connector at a battery terminal has a nasty habit of corroding inside the connector where you can't see it and causing problems. I'd much prefer to see a battery cable with a formed end and the axillary wires, with soldered ends, connecting at a junction block away from the battery.

Joffroi

Just to double check here, you are saying my mystery wire currently hooked up my fender should also be connected like where the red arrow points below. If so, this may seem like a stupid question, but can I put it on the other side where the blue arrow is pointing?

V2RHq.jpg

Since the end connection is not a U shape, but an O shape and its suppose to connect to the ground end, how could it have got disconnected in the first place?

Thanks for the info

EDIT: Connecting the wire to the same end of the red arrow didn't seem to help.

oldcutlass

Did you trace that wire back to its origin. I don't like to connect wires of unknown origin to anything, thats how melted harnesses happen.

If the car is running and you disconnect the postitive wire at the battery, does it stay running? The car should only need the battery to start.

Texascarnut

There should have been no anticipation that changing the connecting point from one side of the terminal to the other was going to change anything.

Is that grungy white wire as stiff as it looks in the photo? If so it should be replaced to insure a good body ground.

With that said everything going on beyond considerations to wiring connectivity issues implies a coil in a relay or diodes in the MSD module is more than likely the problem. Simply put, a bad connection is a bad connection and does not cure itself even temporarily, as you have indicated to be the case. On the other hand, a saturated coil of any nature will cool and may temporarily return to functionality, same is true for ignition control modules with failing diodes.

I would also suggest that if the sound system includes a monster amplifier that you disconnect that sucker at the point it is wired in to see if that is not the problem due to improper power connections.

MDchanic

Except that a bad coil or MSD amp. would not have caused all the rest of his electrical system to turn off as well.

I'm not saying the coil and amp. are good - I have no idea - but I think the offending problem is bigger than that, and if he's got a disconnected body ground wire, that'd kinda do it for him.

One thing I would also recommend would be to look for a ground strap going from the back of one of the heads to the firewall - it's supposed to be there, but the fact that you've got a (disconnected) body ground by the battery would imply that it's not there anymore.

If that body ground has been disconnected the whole time, you could have been running current through some other unintended route, as Stellar said, such as your shift or throttle lingage or your speedo cable, in which shifting gears or turning a corner could kill your car, and the parts conducting the current could be damaged.

It sounds like you have to start from scratch and check continuity through that ground wire (or a new one if you don't like that one), and make sure that you have solid, direct grounds from the battery to both the engine and the body, and also good hot connections to the starter, the alternator, and the body distribution terminal.

Once you've done that, we can talk more.

- Eric

Joffroi

The car is no longer working / running.

I tried looking for older engine pictures in hopes of seeing where the wire may have originally come from. Unfortunately, this is the best I could find.
pEvhQ.jpg
It looks like the currently unplugged end was heading towards the headlight region. Since nothing electronic is working on my car now, is it possible that this was a ground for the headlights? Yesterday, I looked in that area and saw the typical smaller wire that was grounded to a surface there.

I'll check what you suggest MDchanic.

As another test, can I just unplugged everything from the battery except the hot wire going to the starter and my ground going to the engine block just to see if the engine turns over?

Texascarnut

Amen to starting from scratch, meaning in my mind grabbing a copy of the original wiring diagram for the car and putting everything back as it started out as being.

The problem with attempting to figure this out is we ain't there and don't have the whole picture and have no idea what may well be in between the battery plus side and ground that shouldn't be in a circuit where it may be or is flat missing, as in body to block ground strap. Too many possibilities to just be guessing at, might even be an ignition switch, neutral safety switch, or even headlight switch (if primary to ignition switch is routed through it). Two or three hours with a VOM might get to the problem!

MDchanic

No. You need power to the body to go through the ignition switch and pull in the starter solenoid.

- Eric

oldcutlass

I would follow each wire to its source/ or destination to insure its a positive or a negative of those connected to your battery. Guessing = major problems and unneccessary agrivation.

MDchanic

I agree. The wiring has obviously been heavily modified (*ahem* "messed with"), so all bets are off as to what connects to what, and our guesses, based on what should connect to what, may be way off.

Best to figure it out from scratch, and make a new digram of how it's all hooked up now, then make sure that diagram makes sense and is safe.

- Eric

Joffroi

I'll try to see if I can get a block of time this weekend to kind of draw everything out. As you mentioned MDchanic, it has been heavily "changed". Looks great, but I got a lot of wires getting rapped up to places and it will be pretty difficult to follow.

Back to the "unplugged white wire", is there a chance it was just never plugged into something in the first place (doubtful I know)? And with the bad images somewhat showing that it is coming from the headlight region, is there a change it could have come from there?

Thanks

MDchanic

Anything is possible.

Someone messed with the wiring, and that someone wasn't you.
(If is was, it would have been "customized" rather than "messed with" )

- Eric

Texascarnut

Little to no chance! No evidence GM has ever wasted a foot of wire. You really need to acquire a copy of the factory wiring diagram otherwise you are just guessing and grabbing at straws.

Joffroi

The electronics here are by no means close to factory. That is the only reason I suggested that.

Texascarnut

Supposedly not being close to factory is exactly why you need the original wiring diagram in order to see where errors in modifying and adding aftermarket stuff to the car may have totally messed up the entire electrical system.

Sorry, but there doesn't appear to be an easy way out of the circumstance.

yeahbuddy

Completely off topic but your 442 has been my wallpaper for the last week.

Joffroi

It may not run now, but it can still sure look good! Here is one of the pics I took before it stopped working

https://i.imgur.com/WsMfe.jpg (really high resolution)

(just a 442 Clone )

yeahbuddy

Nice! My wallpaper is the one posted on street with the brush in the background. Looks good. Hope you figure out your issue.

Joffroi

I checked the ground from my battery to the engine block and cleaned both ends. I found the ground wire going from the heads to the firewall. Wire looks good and cleaned both connections. I followed the wire from the battery to the starter and it looked good. My headers were getting in the way, but all the connections there look pretty clean. I followed the connection to the alternator and it looked clean and not damaged. Pardon my ignorance... how can I check the distribution terminal?

If all this fails, I'll try to find time this weekend to ensure my starter connections are clean (that wouldn't effect my electronics going out though right?).

I found the wiring diagram for a 71... is it essentially the same? If not, does anyone have the original diagram for a 72?

Thanks again for all the help. I really appreciate it.

Texascarnut

You really haven't looked very hard for a wiring diagram have you? Apparently google has escaped you!

http://www.justanswer.com/car/0qus5-...tlass-442.html

stellar

Have you checked the ground from battery neg post to body?

Joffroi

Since my grounds appear to be OK, I'm going to start checking things with a multimeter this weekend if I can find the chunk of time. Is it possible it could be a fusible link somewhere?

oldcutlass

Fusable links are not intermittant.

Texascarnut

This may be one of those cases where your prediction of

There is nothing that can't be solved with a suitable amount of explosives

may well be applicable.

In this case I figure about 1/4 stick of dynamite strategically placed should do the job.