Help Please Damn Car

[Red76Vette]

Okay I went today to an auto electric shop and talked to the guy he said for my application that wouldn’t work the short has to be present for that to work. My problem is very intermittent so for now because I don’t have money to fix it. So I bought a 15 amp circuit breaker that snaps right into place this way when It pops it just resets itself works nicely. For a temporary fix till I have the money to take it to the shop and have them look at it. I can’t for the life of me determine what causes it. I just know it works sometimes and doesn’t other times.

Thanks,
Chuck

 

[resto75]

I got in went out to dinner ate came out tried to start my car and nothing.

What did you EAT for dinner. Uncle Dans high power explosive chilli ???????

 

[Red76Vette]

Close a carne asada burrito a big one.

Late,
Chuck

 

[lone73]

Chuck,

Do you have a DVM? (digital volt meter) The next time you park it pull one of the battery cables off and put the DVM inline set to read in amps. If your short is active you will see some number of amps draining from your battery. Start pulling fuses out of your fuse block while monitoring the DVM. If you pull one that causes the amp rating to drop near zero you should be on the trail to solving your problem. I think the clock will pull a small amount so it may not drop to zero. You'll need a schematic of the electrical system to go further. I would isolate a few connectors in the offending circuit to disconnect after that to further narrow it down.

good luck bud

lone73

one other thought...
Are you positive your battery is good?

 

[dmrodco]

lone 73

Great tip ! ......

 

[Red76Vette]

Thanks for the advice Lone73 ill have to try that but what about this? Okay Last night I drove home my lights were on bights also I have a stereo high power that is on and I put it into reverse everything starts dieing out, lights dim etc. What is the cause of this do the two reverse lights take that much power to start shutting stuff down or is my battery not able to handle the drain on it? Do I need something more powerful, is there a battery I can get that will put out a lot more power? I think this will solve a lot of my problems. I have the stock battery recommendation from pep boys (Pro Start) not that good of one if I get a better battery I think it will help.

Thanks,
Chuck

 

[cntrhub]

Since it is intermittent, i am trying to follow the things you say. I may be going the wrong direction on this. That said, I am thinking that when you place the shift lever in reverse, this triggers a problem?
What I do not know is, if the reverse back up lights/safety switch use the same fuse?
..... "put it into reverse everything starts dieing out, lights dim etc."... Ok, so you put it in reverse, does the fuse blow? You have your brake on, which obviously, the brake lights come on. Then the back up lights come on from the switch at the shifter lever.
Pull that 15 amp breaker, and fit the correct fuse in it. Step on the brake, place it in reverse. Do this just one time. See if the fuse blew?
This is an electrical problem, so you do not need to start the car. Just cycle the key on and off, going through your brake/shift routine. If the fuse did not blow, try the routine a few times with the shifter going in and out to trigger the reverse safety/back-up light switch. My thinking is that the wire off the reverse/safety switch is grounding when it receives current? It's easy to do, what do you have to lose?
Yes, brake lighs on, really pull a lot of current. If they hand you a second Pro Start battery, bite the bullet and go Delco.

 

[lone73]

Chuck,

Looking over the '75 schematic in my Chiltons (there is no '76 schematic) It looks like the back up and turn signals are on the same fuse. Power comes directly from the ignition switch. The terminal inside the ignition switch that supplys power for that fuse also sends a signal to the alternator. If that's the voltage sense line, and I'll bet it is, then that might explain why the alternators are going bad. It's sensing low voltage and requiring max output from the alternator when the short is active, or just downright trashing them immediately.

I'll bet the reason you went thru 5 alt's is because the short was always active and causing max current flow thru the brown 20guage wire (again, assuming that is the sense line). After the 4th alternator the short opened a bit and is now intermittent. Intermittent shorts are an electronics tech's worst nightmare.

Did you buy that DVM yet ?????
I might be on the trail for you here but I need you to measure 2 things first. there is a two wire connector that plugs into the side of the alternator. with the ignition switch OFF pull that plug off and stick one of the meter leads into the hole with the brown 20 guage wire. put the other meter lead to a KNOWN GOOD GROUND!! You should read an "open" or infinite resistance. Now measure the resistance between the hot side of the 20A turn/back up fuse and this same brown wire, leave the fuse in and both sides will be hot obviously. You'll probably have to use a piece of wire to extend your reach with the meter leads. Judging by what I read in my schematics you should get a very low reading, like maybe 1/2 ohm or less.

I'm betting that one of those two tests will show you a prob. My best guess at this point is that when your engine was replaced they boogerd that brown 20 guage wire somewhere or the connector at the alternator end.

Other possibilities are...
1. your ignition switch is bad.
2. steering column movement has abraded the brown 20 guage wire inside the column. (lets hope it isn't that!)

let me know what you find...

good luck.

lone73

 

[Grasshopper]

Hey chuck,sounds like you have problems.I would start with buying a manual on that veh. Start with checking your engine and body grounds make sure they are clean and tight.then follow the wireing from the alternator as described in your manuals charging system diagram by the way what does your amp gauge show when its running? in ref. to your blinkers if they come on but dont flash it may be the littie flasher box itself or blown bulbs that may have gotten blow from something grounding out the systeme.you are going to have to get the manual and a good test light.let me tell you about an elec.problem i had.simular prblems all through my chevy turned out it was a blown tail light bulb the element inside the bulb had grounded to the side and was backfeeding through the system.good luck i will check back with you later.

 

[Red76Vette]

Okay that’s a lot to take in I have to wait till my pops gets home he has all those goodies in the van he is an electrician. So it is just a matter of me getting the DVM out of the van when he gets home and ill try to check. Thanks for all your guys help I appreciate it very much.

Thanks,
Chuck

 

[Red76Vette]

Okay I played with it a little today I am getting about 12 amps when the car is running which is right around what I should right? Put a good 20 amp fuse in turned my signal on stepped on the break and put it into reverse and the fuse blew so if that info helps determine the problem that is great. I do not see a brown wire I have a red one which I assumed was the one I needed to use I couldn’t get a reading off that but I don’t know that I was doing every thing you said correct lone73. I am not all that familiar with what I am doing and I have a 76 passenger car service manual which I don’t know what exactly I am looking for in it. Also it is kind of confusing due to the fact that it has all the cars in 76 in that same book. I need to be walked through it step by step pictures are great or if I can call one of you I would be willing to do so. I am so very appreciative of all the help thus far thank you all so much.

Thanks,
Chuck

 

[VRGSVET]

I would really like to help on this one. I've got 13 years experience troubleshooting wiring problems on F-16s and F-117s in the Air Force. Unfortunately, I'm in Korea right now and don't have access to my schematics. Based on what I've read so far, you definitely have a short. And, I think it's a constant short. But, only when that circuit is activated, does it cause the problem, making it look like an intermittent short. From what lone73 says, the reverse lights and turn signals use the same fuse, which gets power from the ignition switch. Your short is most likely somewhere between the fuse and the reverse lights or turn signal lights. If a wire is shorted, you may need to bring it to a professional. Since I don't have a schematic here, I can't offer much help in narrowing that down. There are a couple easy things to try though. First, check ALL your light bulbs and their sockets. If the socket gets corroded, it may be shorting through the bulb's metal base. Also, check the reverse/neutral switch, especially the wiring and connector on it. Check for any bare wire, and again corrosion in the connector. I'm frustrated here, because this would be an easy fix for me, if I wasn't half way around the world. I'm curious, check to see if your reverse lights stay on all the time, while driving, or do they come on when you hit the brakes? I wish you luck with this one.

 

[lone73]

No brown wire ??

Chuck,

No brown wire huh? That sounds a bit suspicious. Also, 12 amps thru the fuse? Is that what you're saying? Where did you measure that?

I only have '75 and '77 schematics though. This may be a showstopper for me. I'll look at the '77 schematic when I get home tonight and see if there is only one red wire to that alt connector. I get home about 8PM Texas time.


You said that you had a high power stereo. Where did you get power for it, the amp or anything else aftermarket ?


later

lone73

 

[Red76Vette]

I am sorry I am getting 12 volts DC from the bat my fault I miss wrote. Yes 2 amps 1000 watt and a 600 watt but I don’t think that is causing any problem because I am having no problems with them. Today I tried to check and see if it could be corrosion in the reverse lights. I didn’t find anything wrong I tried to see if there was any thing wrong with the lights them selves nothing all of them break, reverse, and blinkers go on and off etc. I did find a half taped wire in the back that looked like it could have been hitting the frame but not likely the problem it could but would have had to travel about 2 inches to do it. I don’t think that was the problem.

Thanks Chuck

 

[lone73]

I 'm thinking at this point that you might hav 2 different prob's going on. I at first thought (hoped) that the tail light fuse blowing might be related to the battery going down but going back over what I remember of the schematic in my head today I don't see how they could be related. It does sound as though VRGSVET and others are correct in the short assumption between the tail lights and the fuse block but the problem is which leg? Is it the turn signal leg or the B/U leg of the wiring. Not only that...VRGSVET, talk to me here...the short is not a direct one or it would blow the fuse immediately when either the B/U lights or the turn signal was activated. That doesn't always happen apparently. It sounds as though the load on the fuse just increases to the point that it blows when both are on at once. That leads me to think that you (Chuck) got some other equipment on that circuit that's sucking down some current somewhere. Maybe that is what's causing the alt sense line to go low. I dunno, let me think about it some more.

lone73

 

[lone73]

Ok here's another thing to try. With the key off, the turn signals OFF, and the car NOT in reverse take out the turn signal fuse and measure between the DOWNSTREAM SIDE of the fuse and ground. Should be an open.

You said 12V when the car is running? That is too low. Try removing one of the battery cables with the car running. Car should not die. If it does your alt isn't putting out.

lone73

 

[lone73]

The brown alternator wire

Chuck,

I just checked my Chiltons schematic for the '77 model alternator. (these schematics are pretty bad BTW) It shows 2 wires, one red and one brown going to the alternator connector also. I'll bet your car is SUPPOSED to have that brown wire in the connector. Maybe someone with a '76 can chime in here and reveal this mystery for us. I'll bet this is at least part of your charging problem. You need to find that wire.

I just went out and looked at my '73, the brown wire just comes out of the harness with the rest of the wires going to the alternator. Your brown wire may be clipped off, back inside the harness. Take a look, don't hook it up yet if you find it. If it's been intentionally clipped back, whoever did it was probably trying to band-aid another problem they couldn't fix.

let me know bud...

later

lone73

 

[Red76Vette]

Pics hope this helps!

Thank you lone for all your doing for me I owe you one bud.

Thanks,
Chuck

 

[Red76Vette]

Its late will try tomorrow thanks again lone73

 

[Red76Vette]

Better pic!

Thanks