Electrical Issue - Need help

[Lin]

Last night I took my recently restored BT7 out for a drive, returned and parked in the garage. Ran beautifully and I am pleased with how everything has performed. UNTIL,today I jumped in to start the car. When I hit the starter button there was a brief click and then everything was dead.This was not the first time out. I probably have about 5 hours driving time with all components working fine.

Those items not dependent upon ignition switching such as lights and horn were unresponsive. With ignition switched on everything is dead also.

I suspected the battery or a battery connection, because there was no heat, smoke or other signs of a typical short. Tested battery and it is strong. Checked boot switch and it is functioning properly. A test light shows current at the battery to solenoid connection. The positive post on the alternator also lights as you would expect.

Since I am using the alternator, my voltage regulator box has the brown and the brown/blue wires connected together on one terminal. The yellow wires are joined together on another terminal. The brown wires show voltage when checked with test light. Yellow do not.

No fuses blown. The upper non-switched fuse block terminal is live and lights with test light. Though the horn and lights do not work. The lower switched terminal is not energized on either side of the block.

I checked the ground straps in the boot and the one from the engine to the frame. Both new, both securely fastened, and yes I scraped the paint of first so they would have a good connection.

So what is the problem? Can anyone help?

Lin
1960 BT7 "The Bloody Beast"
1959 Bugeye

 

[GregW]

Hi Lin,
Did you check everything with the bulb tester, or did you use a voltmeter? You might be able to get a little bulb to work, but not have enough juice to get other things to respond. Did you check fluid levels in the battery?

 

[Ed_K]

Hi Lin,
I just got back from a night drive in my BJ8. I am sorry to hear you are having trouble.
It sounds as if your battery is weak. If it is a new battery then it is unlikely to be the cause of the problem but it is not being charged for a couple of reasons that you will have to check/eliminate.
1.. No output from your alternator.
2.. A poor connection from the alternator, through the big wire to the starter solenoid, back to the battery.
3.. A poor ground on the battery through the switch, to the frame.
I think you said you used a test light. That will not really help much when trying to figure out if a connection is poor. A test light does not draw any current so It won't show a poor connection. It will just show an open or no connection.
......
Step one would be to see if you can start it using jumper cables
from a good battery.
If you can start it, then put a voltmeter on the output of your alternator using engine ground as reference. When the car is running, your alternator should be putting out a lot more than 12.75 volts say at least 13.5 volts. If not, then check the belt tension 1st.
If your alternator is putting out more voltage than you measure on your battery, then I would suspect a bad cable connection to /from the battery or to the big wire on your alternator. If you still have your original rotary switch on your battery ground that is also suspect. Remember that a test light won't tell you if the connection is poor because it takes very little current to light the light. It takes a lot to start the car. A better way to check for a poor connection is with a volt meter across the connection. There should be close to zero volts shown UNLESS there is a poor connection in which case you will read some voltage on the volt meter.
If you don't have a volt meter, any cheap one from radio shack or Walmart will work just fine.
Let us know what you see and we can help you isolate the problem ( hopefully ).
Ed

 

[Ed_K]

Hi Lin,
Did you check everything with the bulb tester, or did you use a voltmeter? You might be able to get a little bulb to work, but not have enough juice to get other things to respond. Did you check fluid levels in the battery?

... Great minds think alike ...

 

[Lin]

Greg and Ed,
Thanks I will check it out tonight after work. I used a test light, but I will hook up my multimeter this evening.
Lin
1960 BT7 "The Bloody beast"
1959 AN5 Bugeye

 

[Andy65]

All of the above is good advice. Using a voltmeter, just start tracing it back from the battery and you will get there. Don't overlook some of the screwball things. A fuse may test good when removed but the holder may be corroded not allowing current. Check the ignition switch. Do all this with a good battery and let us know what it was.

 

[Patrick67BJ8]

A test light is better to check voltage with. When the light lights up that means current is flowing.

A voltmeter can and will show voltage but there might not be any current flowing. I spent several hours trying to repair lights in an aircraft cockpit one evening and although there was voltage measured with a voltmeter at both terminal ends of the circuit breaker the lights still would not light. After I hooked up a home made light tester and tested each terminal did I find the output terminal to the lights had no juice.

Think of electricity as a water faucet: Voltage is the water at the faucet and when it is turned on the flowing water is the current.

Both voltmeters and light testers are good tools to always keep in your tool box. The multimeters are especially good if they have a ohmeter to check continuity.
Patrick

 

[Lin]

Thanks to all who responded to my plea for help to sort out the
electrical problem I was having. Special thanks to Greg, Ed, Andy and Patrick.

These cars do have a way of humbling you! I feel a little silly, but I did learn some good things from this experience about the sequencing of tracking down an electrical gremlin.

I have about 4 connectors for various purposes on the incoming solenoid post for the battery cable. Even though the nut securing the terminals on the post was tight, I loosened it and tested wires one at a time for juice. Everything worked as it should. Turns out that I just restacked the terminals on the post, put a little dielectric gunk on the assembly and tightened down the lock washer and nut.

Just like that, full power restored - everything working! I am extremely pleased that I had no faulty components and that I did not have to stand on my head in the engine bay for long - but I also feel a little silly that it was such a simple thing.

Again, thanks to all. The weekend will be much better knowing that I can drive my car, rather than having to fix my car.

Cheers!

Lin
1960 BT7 "The Bloody Beast"
1959 AN5 Bugeye

 

[Ed_K]

Never argue with success.
Good Show !
Driving IS much better than fixing !
Ed