65 power failure

[kpauley]

I'm having an electrical issue which is troubling me. This car is new to me, have had it for a month, so I don't have a lot of history with it.

I got stranded a few weeks back, had to be towed. Car was running fine, backed out of a parking spot, turned on the headlights (they were down, hadn't rolled them up yet) and the car died. All power was gone. After towing it home and tracing down a bunch of wires I pulled off the cable in the engine compartment that connects to the back of the fuse panel on the firewall (there are two, this was the left one if you are standing in front of the car facing it). One of the lower connectors looked a little bent and like it had seen some heat. I plugged it back in and all the power came on. I figured I would replace that harness soon and thought I found the problem.

Well, it died again. Something seems to be shorting out. Symptoms are when you turn the key on (not to the ACC side, the ON side) the interior lights will all go out and all power is gone. Sounds like a short in the ignition circuit. Power slowly will come back on if you wait, I think. Or some of the pushing around of wires brings it back. I thought it was the ignition switch itself, still could be I guess. I'm also suspecting the voltage regulator.

Previous owner installed an MSD ignition in this car, I am not too familiar with that and I'm afraid that will make the diagnostics more troublesome.

A couple questions for all of you:
1: Any ideas based on what you are hearing?
2: Suggested diagnostic techniques?
3: Tips for removing the voltage regulator? Currently it seems like a two person job because the rubber bushings that it screws into are spinning on me, so I think I need to get under there with pliers to hold the back end while someone else removes the bolt.

 

[WayneC]

One of the most common problems of that nature is corrosion in the junction block that joins the engine wiring harness to the body harness... the one you inspected. Clean all those contacts thoroughly, and be sure the junction block halves are held tightly in place. One of those wires is the main power wire to the ignition switch; I think it's a 12-gauge red wire that goes from the large "B" terminal stud on the starter solenoid (the stud for the battery cable) to the center terminal of the horn relay (mounted on the radiator support, driver side) and then back and through the firewall junction box to the "bat" terminal on the ignition switch. Check all those connections clean & tight... some Corvette owners even hardwire (soldered connection) that particular wire to bypass the junction box.

Another possibility (besides the ignition switch) is a bad headlight switch, a corroded, cracked, or loose battery cable clamp, a poor connection in an aftermarket battery cutoff switch, or even a bad battery cell.

There are several main grounding points for the Corvette wiring harness that could also be a problem; the one for the engine harness is on the radiator support... look for a screw that goes through a multi-wire connector into the support.

I'm sure there are more possibilities, but those are common problems causing the loss of power you are seeing.

I don't think the voltage regulator would be the culprit, but maybe someone else knows different.

Get yourself a Chevy shop manual for your 65, it's the best investment you can make.

Good luck, and welcome to Corvetting!

 

[IH2LOSE]

KPAULEY

I know it sounds silly but do you have a good batteryHead light motors take a lot of juice to open them up.When I have a problem I always start with the basic's

1-Is the battery good?
2-Are the battery conections good(that means remove them and clean them)
3-Is the alternator charging and maintaining the battery charge
4-Is the belt tight to the alternator

I can go on but I always start with the basics first.And Iam correcting future problems /gremlins as I go along.Its also the best way to realley get to know your new car.

Good Luck and be safe

 

[kpauley]

I should have mentioned that the battery and alternator both seem to be fine (I had checked the alternator previously, it is not running now though so it is hard for me to check - I may take it down and have it bench tested to be safe). The headlight motors both seem to function fine as well (when they have power. Thanks for asking, sometimes the basics are overlooked.

Since the firewall connector failed once before I am suspect of it more now that I know it is a common issue. I will clean it up real good with some contact cleaner and make sure it is hooking up well. Replacing that engine bay harness does not look to be too bad, but replacing the fuse panel on the inside looks like a big job because the wiring harness is connected to it I think. Can you replace just the fuse / connector block?

I'll also chase down the grounds and check out the headlight switches to be sure they are all good as well.

Thanks for the advice from all, gives me something to look at today!

 

[Ron Miller]

I believe Lectric Limited, who make a great deal of the aftermarket Corvette harness for these cars, also makes and sells only the fuse block/connector, although I understand it's a pretty good job to change out one. Their products are distrubuted through a number of the aftermarket Corvette suppliers, as well as sold directly.

rlm:cool

 

[WayneC]

Bear in mind:

The charging system is probably not a cause of your problems, it can cause battery power to drain off over time, but is not likely to cause an intermittant full power failure (you can remove the alternator and the car will still run); a short circuit is also unlikely... you're dealing with an unfused power failure, so a high-amp short circuit would produce heat and sparks and smoke and smell, and would be quite easy to spot.

You're looking for an open circuit caused by a loose or corroded connection, and very likely in the path I described previously for the red wire, or in the battery cable connectors at either end of the cables. As IH2LOSE says, don't just look at connections, take them apart, clean them of all grease or corrosion, put a little dielectric grease on them for protection, and re-fasten them (with the battery disconnected, of course).

 

[kpauley]

I had a couple minutes to work on it this afternoon. I took that connector off again and used some electrical connection cleaner and a brush to clean things up real good. The power wire terminal definately shows some signs of heat as it looks a little melted around that connector. I cleaned the battery terminals off while I had them off as well.

Put everything back on and the dome lamp slowly came up, so I knew the problem was still around. I had my wife get in the car to turn the key to ON so I could look and listen under the hood. Saw a nice little spark on the positive battery terminal and heard a little noise, could have been at the battery or it could have been coming down from the starter, hard to tell. All lights went out inside. They started to slowly come back on again but I ran out of time to work on it....

To me, it seems like I have a short somewhere to get that kind of reaction from the battery terminal. I was going to get under and look at the starter connections next time I have a chance.

If you have ideas, let me know.

By the way, nice forum here. I used to have a 96 Impala SS several years ago, those guys are really big into using the Internet for stuff like this, it's a great way to work on things. Glad to see it's not just them!

Ken

 

[WayneC]

>>> Saw a nice little spark on the positive battery terminal and heard a little noise, could have been at the battery or it could have been coming down from the starter, hard to tell. <<<

I think that's strange... why would there be a spark at a tightly-clamped positive battery post? There should be plenty of surface there for current transfer, so the sparks oughta be someplace else. Sorry, I'm thinking out loud. Is it possible the positive battery cable is grounding out to the battery hold-down bracket? Does that cable use the original small "spring-ring" terminal, or does it have a larger aftermarket terminal that clamps onto the bared end of the cable (an obvious place for corrosion to settle in, and a bigger cable connector would more easily contact the battery hold-down bracket).

Why did you say earlier that you know the battery is good?

Next thing I'd check is the starter solenoid connectors, and the far end of the negative battery cable (grounded to a starter mounting bolt or one of the bellhousing bolts, I forget which).

>>> To me, it seems like I have a short somewhere to get that kind of reaction from the battery terminal. <<<

Not necessarily; I think a loose/corroded ground connection could result in more current being drawn to overcome the resistance of the bad connection.

 

[kpauley]

I'll check the stuff out you mentioned. It is the old style spring ring terminals so I don't think it was a short to the hold down. The spark seemed to come from the top of the connector. I didn't have a chance to do it again, I was going to video tape it for the heck of it so I can try to narrow it down and it would be easier to look at it again.

As far as the battery being good, good point I guess. I was checking voltage on the battery and the output seems to be very good. I suppose you could still have good output and there could still be a short within the battery? I've been checking continuity across some circuits to look for shorts and have not seen anything at this point

The starter was recently removed, when the oil pan was removed and some cleaning was being done. There was a lot of oil at the bottom of this engine and the started was covered. It has been cleaned up but it certainly is a part I would not have any issue just replacing. There are certain wear items that when I don't know the history of the car it is just as easy to replace them and they are not too expensive.

I'll probably have more time to work on it this next long weekend

Ken

 

[kpauley]

On to something?

I pulled the starter out because I wanted to clean it up and check it anyway. I checked the wires that were now disconnected from the starter solenoid for continuity with ground. The R connection had continuity with ground. I traced it up to the coil (service manual wiring diagrams are pretty helpful too). It was joined to a connector / wire that runs over to the ballast resistor. Was getting continuity there. Disconnected the ballast resistor and the wire on the engine side is clear, but the wire going into the firewall tested continuous with ground. This is the bottom wire off the ballast resistor, it goes into a harness inside the car. It appears black with a red stripe. The manual I has does not show a wire this color or I am reading it wrong.

I'm thinking this goes to the ignition switch and maybe my problem is there.

I was trying to pull the ignition switch the other day but was having difficulty. I shoved a wire into the hole and was turning it counter clockwise with the key but it wasn't coming out, I'm trying again now....

Ken

 

[kpauley]

I got the ignition switch out now. The only wire that does not test continuous with ground on the connector (switch disconnected) is the purple wire. Seems strange.....still tracing stuff down.....

 

[kpauley]

OK, I've done about as much as I can get away with on Turkey Day, so I'm cleaning up.

I disconnected the light switch, the switch to raise the lights and the ignition switch. I get ground continuity on all the connectors that go to the ignition switch except for the Violet wire that goes to the SOL connector.

On both light switch connectors (motor and pull switch) I have continuity on all connectors. I see some corrosion and heat damage on the pull switch connector.

On the fuse panel, I have continuity to all fuses and ground.

Starter is completely disconnected during this testing, the coil is disconnected and the ground cable on the battery is disconnected. I'm testing continuity to the engine block or the pedals inside the cabin.

Am I going about this the right way? Seems like I have a major problem based on what I am seeing......

 

[WayneC]

Here's some random thoughts...

As you are discovering, to check for continuity to ground where continuity should not exist, you have to isolate sections of wire, based on the wiring diagram; even then it is not always possible to isolate everything.

>>> The R connection had continuity with ground. I traced it up to the coil <<<

I suspect that's normal, as the coil is grounded.

>>> It was joined to a connector / wire that runs over to the ballast resistor. Was getting continuity there. Disconnected the ballast resistor and the wire on the engine side is clear, but the wire going into the firewall tested continuous with ground. This is the bottom wire off the ballast resistor, it goes into a harness inside the car. It appears black with a red stripe. The manual I has does not show a wire this color or I am reading it wrong. >>>

My car is a 63, and the 63 manual shows that wire as purple, going from the firewall ballast resistor to the IGN terminal on the ignition switch, then to the fusebox, feeding the light switch, parking brake alarm, and fuel guage, among others, which gives it continuity to ground... that's the problem with checking continuity: it doesn't tell you anything about load capacity, and some things may be purposely grounded through resistors. For example, your problem is probably not past that 3-amp fuse, or it would blow, but if you remove the fuse, perhaps continuity to ground should be broken (engine side of the firewall resistor disconnected) , and if not, that wire is grounding somewhere.

The "Question of the Day" might be whether the BAT and IGN terminals have continuity to each other and not to ground with the switch on (with all wires disconnected from the switch)... the diagram shows a ground terminal on the ignition switch but no wire to it, so perhaps the body of the switch is grounded thru the switch body? I don't know. I do know the instrument panel is grounded via a wire attached high on the center rear of the panel. So if there's continuity from the BAT or IGN terminal to the switch case or a ground terminal (all wires disconnected from the switch), I think that's likely a switch problem. I don't have a switch handy to check that here, although I may be able to dig one up later today.

Another thought: if the ballast resistor is bad, the usual symptom is that you can start the car, but as soon as you release the ignition key from the start position the engine quits, but I don't think the power to lights and accessories, etc would also fail; I think you could replicate that failure by simply disconnecting the purple wire at the resistor. I don't know if there is such a thing as an intermittant failure of the ballast resistor (it's a pretty simple part), but I guess it's possible, perhaps due to heat buildup.

>>> I got the ignition switch out now. The only wire that does not test continuous with ground on the connector (switch disconnected) is the purple wire. Seems strange.....still tracing stuff down..... <<<

When you say "switch disconnected" I'm not sure whether you mean out of the dash, or all wires except purple disconnected, or what. If you mean with the switch out of the picture, that all wire terminals that would connect to the switch have continuity to ground, I'm not surprised by that (see my prior thoughts on grounding & continuity).

I've heard the directional signal switch at the base of the steering column can also cause problems, because it aggragates 6 wires, but I can't tell you much more about that.

Wish I could be more help.

Wayne

 

[kpauley]

Wayne, thanks for your post.

When I was stating that the switch is disconnected I mean that I have it out of the dash and the wiring harness connector has been removed from the switch, so the switch is physically out of the car and the connector is just hanging there.

The ballast resistor has been removed as well and is physically disconnected. If I put my meter on the lead that connected to the bottom and goes through the firewall into the car and the other meter lead to ground I get continuity. Same thing with the connecters that plug into the switches, I touch each of the blade connectors within the plastic housing and the other end to ground and I get continuity.

During these tests, I also had one of the firewall to fusebox connector removed, the one that I was suspecting earlier in the thread. After I cleaned up I was thinking I want to remove the other connector as well, this would pretty much isolate the lighting circuit I believe, I need to look closer at that wiring diagram.

Something just doesn't seem right, getting continuity with ground at the fusebox really seems bad. It just seem strange to me that it is across all fuses.

I have this feeling that it is going to turn out to be something really obvious, I hope don't have to replace all my wiring to figure it out though!

Again, thanks for the post. I may get back out there tomorrow and tear more apart!

Ken

 

[WayneC]

>>> Something just doesn't seem right, getting continuity with ground at the fusebox really seems bad. It just seem strange to me that it is across all fuses. <<<

Again, that's probably to be expected. It's difficult to isolate a circuit. Every circuit is grounded someplace, and in many cases the hot and ground wires for different circuits are aggragated at a single point in the harness.
For example, the red 12ga hot wire (coming through the firewall connector to the BAT terminal on the ignition switch) branches out upstream of the ignition switch (to the cigarette lighter, the headlight switch, and the fusebox, among other places)... if any one of those branches leads to a ground, even through a resistor or coil or motor winding, it will give you a continuity reading to ground on all the other branches, albeit maybe not zero-ohm continuity.

My bet is still on the firewall connector or the battery, a poor connection rather than a short.

 

[kpauley]

Good point Wayne about how much continuity, I was listening for the beep on my meter but not looking at it to see if it was zero ohm.

I did a couple quick things this morning then I figured I'd sit down tomorrow with the wiring diagram and re-check a few things, including the ground point you mentioned.

I put the meter on the disconnected battery ground and on the hot terminal which is still connected, no continuity at all.

Then I pulled all the fuses, mine has just the six fuses. I checked for continuity on each side of the fuse block, the fused side (right) and the non-fused side (left). Here's what I found (along with the ohm reading on the meter

All fuses removed at this time, X = no continuity, a number represents what the meter read, other lead touching brake pedal metal). Both connectors removed inside the engine compartment on the back side of the fuse panel:
Brake: Left = X Right = 57
Heater: Left = 53 Right =X
Radio: Left = 56 Right = X
Panel: Left = X Right = 4
Tail: Left = X Right = X
Courtesy: Left = X Right = 4

So the Tail is the only one that did not have any sort of continuity reading.

Same test conditions above, but with the fuses put back into place (I did not measure both sides at this time since the fuse was in place):
Brake: 57
Heater: 53
Radio: 56
Panel: 2
Tail: 3
Courtesy :3

The tail fuse has continuity of 3, only when the courtesy fuse is put in.

During this test the iginition switch and the light switches were still unplugged.

Not sure if this tells me anything yet, but thought I would put it out there in case someone might have a chance to meter theirs as a comparison or this might be a clue to someone.

 

[WayneC]

>>> The tail fuse has continuity of 3, only when the courtesy fuse is put in. <<<

That might be a good clue.

I AM surprised that there was no continuity ohm reading on the tailamp downstream fuse connector... regrettably, my 63 body is off the frame, tailights out, and quite inaccessible right now, so I can't check my car.

If I read the diagram right, that circuit (black wire w/ white trailer) seems to gound inside the car... somewhere... maybe under the passenger dash, into the crossbar support, I don't know. There are no b/w wires in the firewall connectors, so it must ground inside the car. A ground strap on the left firewall body mount grounds the body birdcage to the frame; another at a motor mount grounds the engine to the frame.

One branch of that ground circuit goes to the back of the instrument panel (there's a spade connector very near the top of the back of the instrument panel, between the tach and speedo, but closer to the tach). That ground circuit also passes through a body-harness-to-instrument harness connector just beside and inboard of the headlight switch, atop the dash lower cross-support . It would seem to me that (with the courtesy lamp fuse removed) if you touch a probe to the rear of the dash panel, you should have continuity to any other b/w wire, and to the vehicle frame.

BTW, I found some old notes I made from a web post that said the part numbers for the terminals inside the firewall connector boxes are 2973915, 916, and 917 (depending on the wire gauge), and that these could be replaced individually, but the poster didn't know which was which, nor where you could find them for certain, except in quantity. Perhaps Lectric Limited, one of the Corvette parts houses, or Pioneer Packard might sell them individually. I don't think you can replace the entire connector box assembly; the firewall side is actually the back of the fusebox, which may be available from harness vendors separate from the dash harness (although an awful LOT of work to replace), but the outer halves are part of the engine harnesses.

 

[JohnZ]

Ground continuity checking is fine if you're trying to find an open circuit or broken wire in a harness, but is of limited usefulness for anything else. Every electrical component in the car is grounded, as that's their current path back to the battery so they'll operate when they see 12 volts applied to them.

You'll have better luck putting power on the system and then using a test light to a known good ground to see where you have power and where you don't, using the circuit logic from the wiring diagram.

 

[kpauley]

Well, I put things back together, fixed a couple ground issues I saw in the engine compartment (ground from battery to bellhousing, there were a couple other wires grounded there that were pretty fragile so I re-did those).

I put things back together under the dash as well, to get a fresh start on things. I found one lead to the courtesy light on the drivers side falling apart, fixed that as well. Those lights seem a little touchy, move them around a little (either one) and the lights flicker.

I'm back on the light switch. This is how the first episode happened, when I turned on the head lights. Jiggling some wires around there seemed to affect the interior lights (flickering). I pulled out the light switch and all interior lights went out.

My father in law is coming by tomorrow, he's an electrician and a fresh set of eyes....


Could be a bad switch I suppose, not too sure how to test that or if I should suspect that, or a wiring issue with the lights.

 

[WayneC]

Headlight switches are not expensive($17 at Long Island Corvette), and aftermarket versions are probably available from NAPA parts stores, or visit your local junkyard; except for the knob, I think they are common to many Chevy models. Might be worth replacing just to eliminate it as a cause.