Troubleshooting experts, enter.
 

This happened to me the other day so I figured I would try out everyone’s troubleshooting skills.
Background- 65 Corvette, everything is brand new from the wiring harness’ to the lugs nuts. The battery is one of those reproduction batteries that has the Odyssey AGM inside of it. I’m using a knob type battery disconnect.
Situation- I fire the car up in the A.M. and head to a car show – everything is normal
Park the car at the show and disconnect the battery.
6 hours later, connect battery and try to start it. The solenoid clicks once and then everything is dead, not even a dome light.

Tell me what you’d try and I’ll give you more info. Good luck.:cheers:

sounds like a bad spot on the starter. first wiggle battery connections. if connections appear okay tap starter with hammer. try to start and if still no luck use screwdriver to jumper solenoid and starter.

The knob type battery disconnect probably was at fault. I'm not a big fan of the AGM batteries either.

Bad/loose ground to starter...?

Everything is tight. Remember, even the dome light is out.

I removed the disconnect and put the cable directly to the battery. No change. Odyssey Batteries are used extensively in the airline industry as well as in nuclear subs. Very highly rated.

Everything is tight.

Me and my buddies are really scratching our heads now. I get a ride home and come back with tools, jumper cables, an extra battery and a volt meter. The first thing I check is battery voltage-12.9 volts indicating a fully charged battery.

where do you go from here?????

Check your connector at the firewall. Mine did this when I first got it. Believe only place I would have power was at the horn. Everything else was dead. If I put upward pressure on the connector it would "fire up".

My normal check in such a situation is to put a voltmeter across the battery....I expect to see 11.8-12.5V or thereabouts. If not the battery is suspect. Then take the same measurement while somebody cranks the motor. I expect to see a voltage drop to 9.5-10.2V or thereabouts. If there is NO significant drop then my first suspect is corrosion or loose/bad connections. If the drop is much greater than that I have found the battery may be bad...bad cell or what have you.

Of course, I'm betting is none of the obvious problems or Jim wouldn't be teasing us. Indeed a unique problem to C2s (and my '67 Chevelle) is the firewall connections for the major circuits. It takes almost nothing, current wise, to light a dome light so that is a key clue to what is going on IMO.

Electric connection at firewall..? Happened to me once, a clean up and a wiggle and good to go.

I also had a bad firewall connection once. Took FOREVER to find it. If that connection is loose you will have exactly what you describe..power at the battery and nothing on the interior.

Im no corvette expert but maybe this helps. I had that happen on my 1969 chevelle. that car would even shut down driving for no reason. it had aftermarket gauges in it. PO ran everything through the amp meter. everything except the main starter and ground leads. the wires were just loose on the quage studs. took a while to find it. not sure how your car is wired. I would hook up your volt meter to the - on the battery and look for voltage at the starter, alt, fuses, ign switch etc until you find no power. a test light would be easier to see.

Get out an ohmeter and start measuring where it gets lost.

Have had an auto battery many years ago that measured good (indicated fully charged), but would fail internally (internal open connection). As soon as a high load was needed (starter), it would open up and no voltage was indicated at the battery posts.

Good luck,
Plasticman

Update:

New harness' and connection at firewall is tight.
Remember - 12.9 volts at the battery. I check voltage at alt. battery terminal, solenoid terminal and on the engine side of the firewall connector - 12.9 volts.
Open the door and check the dome light -it's out. Checked for voltage at the fuse box- zero.

Jim

if you take the disconnect out of your circuit do you then get a dome light?


Please clarify where your disconnect is located in the circuit

That's the first thing I did = no change. It was on the neg. cable at the battery

Hi, I have experienced first hand in the past loose connections of the studs on the solenoid. You need to take off the starter solenoid wires and make sure the studs are secure in the solenoid itself. Put a wrench on them and see if they are loose.

EJ

Everything is tight.

Clean your battery terminals and the associated cables, then check the attachments points for the cables at the ground,and solenoid.


Can you short across the solenoid and make anything happen? As in trying to make motor turn over, like you are stealing the car? Any sparks? if you get sparks, you have power to to both ends of the starter, and the problem is in the wiring harness, fusible link, etc. If you don't get sparks or motro turn over, one of your bat cables is bad.

Edit; you could just have bad battery, and it may read 12V, but isn't putting out any amps at any load. Unlikely, but possible. Typically a situation witha bad battery will leta dome light come on, but then as soon as you try and start the car, everything goes dead.

Doug

If I had good power and good grounds I would get out the wire diagram and see where dome light power came from, see if there was anything in common to the start circuit like firewall connection or ignition switch.

You forgot to turn the green knob on your battery disconnect or it was not tight enough.

All good suggestions. No fusible link on a 65 and it has a shield around the solenoid so it was hard enough to check for voltage there, 12.9 volts but impossible to use a screwdriver to short it out. Battery cable and battery are brand new, clean and tight.
Trust me, I'm surrounded by guys that have been building hot rods for 40+ years and we're all scratching their heads.:crazy2:

That was my very first thought so I removed it completely and was preparing my apology to those that are "knob haters".:D

starting at the battery, follow the power path til it goes dead; and there's your problem
Bill

You have a bad connection somewhere. Checking for tightness isn't good enough. You have to clean the connections and reinstall.

Unfortunately it wasn't that simple. I did that and I had power on one side of the firewall connector but the other HOWEVER, that wasn't the where the problem was.

I just finished a complete body off resto. and everything is new, clean and tight. The car has 120 miles on it.

A couple of you are sniffing in the area where the problem was. I'll take a few more guesses before I spill the beans.

I have been following and asking in between boring conf call conversations..


did you say you had/lost voltage at the f/w...no voltage on the fuse block.

Pass through plug on the firewall the problem?

A dead/bad cell in the AGM battery?

At this point I'm almost thinking something went wrong on the ground side of the circuitry.

Power on the engine side but not at the fuse box

According to the battery manufacturer, 12.9 volts indicates a fully charged battery and these batteries don't catastrophically fail. It was working perfectly, sat disconnected for 6 hours and then re-connected.

From a troubleshooting standpoint I would start at the dome light and work backwards using a wiring diagram until I found the problem.

Without being at the side of your car and being that you completed a complete wire harness to lug nut reastoration my guess is you left some grounding straps disconnected or didn't install some of the important one's. Althoug that should not effect the starting part of this unless you have a bad main ground cable goin from the battery to the block.

Do I win a cool one?

It might be a shorted out starter solenoid. It could .be taking all the current to ground

That's what Boeing said about the 787 Dreamliner. :D

You were sniffing around the right area in your first post.

Thanks for everyone's participation.

Time for a re-cap. 12.9 volts everywhere but not at the fuse panel. Sure sounds like the firewall connector to me. I try to wiggle the connector, even though it's tight and check for power at the fuse box, none. This is getting crazy. I decide to regroup and start all over again. Check the battery for voltage - zero. WTF?????? I make sure the leads are tight on the volt meter, 12.9 volts now. In hind sight, at the same time I was checking the volt meter, my buddy who was checking to see if the dome light was on, closed the door. HINT, HINT, HINT.

We tried to jump start the car. It would turn over about one revolution and stop. Possibly too long of cables even though they are quite heavy gauge.

He11 with it, I decide to change out the battery. That's not fun under the best of conditions but on the car show field under a hot sun, it really sux. With a new battery, it fires right up and I drive home with no problems.

I check the first battery again and it is 100% charged according to the Odessey charger that reads voltage and % of charge. I left the charger hooked up to it, in monitor mode only, not charging and tried a small dash light bulb directly to the terminals. The voltage dropped to ZERO, the bulb didn't even flicker and the charger said "no battery detected". I removed the bulb and the voltage went right back up and it's 100% charged. That's why the battery read full voltage everywhere but when I opened the door to check the dome light or for power at the fuse box, it dropped to zero.

The manufacturer is sending a new battery and paid for return shipping of the old one. They have never heard of this happening and said that, basically, it's not possible for a 1/4 watt bulb to make the voltage drop to zero so they're going to dissect it and get back to me.

This episode really had myself and a lot of others scratching their.

Brand new, doesn't mean any good.

You want to find the problem? Start tracing it down, step by step instead of throwing darts.

Doug

Haven't made the switch to AGM yet and in no hurry to do so. Some have phenomenal luck with them -- other folks ? Not so much...

Bad horn relay.

AHA, I win, see post 17. :)

Doug

I told you I don't like the AGM batteries in automotive applications :rofl:

I think I was 10 posts ahead of you.

I guess what threw me and everyone else there was:

1. Brand new everything including the battery.
2. Battery was fully charged and working perfectly when I disconnected it.
3. Battery indicated to be fully charged when I hooked it back up. Why wouldn't it be?
4. Power at the engine side of the firewall plug but none inside the car, not even enough to light a dome light, even an almost dead battery would still light one up.

Logically, everything points to the firewall plug.

It obviously was in the back of my mind somewhere that the battery might be the issue or I wouldn't have brought a know good battery back with me even though the one in the car was "known good".

Thanks for playing.:cheers:

Jim

Jim,

Don't let the battery company know about your secret or the warranty is void....



http://i1091.photobucket.com/albums/...ps2da9d4e6.jpg

Jim
that just doesn't make sense to have power on one side of the 'plug' and not the other///
Bill

:iagree:

check and clean the ground connection from the battery to the frame....many owners don't even know where the connection is...{short cable from battery to frame under or near the drivers seat}

The reason it was like that was I checked for power on the engine side with the door closed so it read 12.9 volts but when I opened the door, the dome light put a load on the battery causing it to read zero so there was no power at the fuse box. Had I left the door open and gone back to check the engine side again or even directly at the battery, it would have read zero.:crazy:

Jim

Not on a C-2. The neg. cable goes directly to the outboard starter bolt. The answer is in post #34.

Jim

:iagree:, just dumb luck/stuff happens...
Bill

Now you understand why it was so hard to figure out. Something as small as a dome light caused the battery to temporarily read zero, otherwise it read fully charged even though it wasn't. A lead acid battery would never do that, but then again, the manufacturer says an AGM battery won't do that either, but it did, to me, on a hot day at a car show. Lucky me.:woohoo:

Jim

i'd have tried to check it with a 12volt test light, so maybe it would have acted like your dome light and i wouldn't have shown a circuit; therefore by dumb luck, i'd have said 'battery'...

or not...
Bill

In hindsight, that would have shown the problem IF combined with the use of a volt meter because the test light wouldn't have lit up making you think it was broken especially when the volt meter shows 12.9 volts. You would then have had to check the test light for proper operation on another car. Then you would start to see the problem. Confusing as he11. I prefer to use a volt meter because that will tell you the exact state of charge of an AGM battery. 12.8+ volts fully charged, 12.6 -12.7 80 %charged down to 12.3 which would be almost discharged but would still brightly light up a test light.


Jim

Buy a new set of battery cables.

They are new. The issue was with the brand new battery. Read post #34 where I explained it all.:cheers:

Jim

:cheers:Thanks for sharing, I am not a fan of AGM batteries, although I have read many advantages, My wifes X5 now 4 years old has an AGM, she told me her air conditioning would not work, I went at it trying to find the source. I could find nothing wrong, I tested the battery voltage and had 12.5 and thought all was good. Did some reading on the INTERNET and found out the Smart Vehicles today see a voltage drop and start shutting off systems to keep the car on the road, one of the first to be shut down was the A/C system to protect the battery power available. After wasting several hours I ended up buying a new battery and all works well again. The X5 starts thinking you are in failure mode when you get down to 12.5 volts. I really don't need a car that thinks for me, it really pisses me off when I try to diagnose using old school skills. I feel your pain and I am glad you figured it out. This will be a memorable car show for you, a reason to laugh over a beer in future.

That was the point of my post. For us old school guys, nothing made sense so think outside the box. Absolutely no test or history of the vehicle/parts pointed towards the battery. As far as the beer in the future, I've been drinking heavily since.:cheers:

Jim

This is why I have a battery load tester. The voltage reading at the battery is nice to know but is a not a guarantee of a batteries health.

http://assets.farmandfleet.com/p600/...oad-tester.jpg

had a similar failure. battery has rivets connecting each cell to the next. rivet broke. current flows thru acid only, so tiny bulb dims. Took off caps. i stuck in a screwdriver (dangerous) while i tried to crank. wiggled it and it fired right up.