67 electrical issue

[Donald H.]

I took my 67 for a drive and everything was fine. The next day I went out to start it and got what I would call one click/partial crank. Then nothing. I hooked up a jump battery and still nothing. Quit and charged the battery overnight. Still nothing. Finally got out my VOM and the voltage at the battery was 12.6. Check the voltage at the battery terminal on the solenoid, 12.6.

After research on the forum and elsewhere, I suspected the ignition switch. Tested for voltage on the purple wire at the solenoid and the switch in crank mode and nothing. I bench tested a spare switch I have and then installed it. Nothing.

Then suspecting the wiring connections at the bulkhead, I pulled then, wire brushed and spread all the pins to make sure there is good contact. I had done this about 6 months ago when I was having battery meter issues.

I check continuity and voltage on the red wire. 12+ volts at the horn relay and back of the alternator. 12 volts at the circuit breaker under the dash. Strange was 10 volts on the red wire at the ignition switch. Not sure about that one as according to the wiring diagram the red wire at the ignition switch come from the circuit breaker.

Some other issues that must be related.

Headlights turn on but not the dash lights. Courtesy lights work. Turn signals work. Headlight motors are real slow and I could not get them fully opened. Horns don't honk. I can hear the relay click and maybe some slight horn sound. So I checked the voltage at the horns. When honked I'm getting 2.2-2.5 volts.

Could the horn relay be causing all my problems?

Thanks,

Don

[Terry D.]

Re: 67 electrical issue

Is the ground to the battery good? Did you load test the battery?

[Gene M.]

Re: 67 electrical issue

Try jumper at solenoid of positive to the purple wire on solenoid. Since you have 12.6 volts on positive cable it should crank. If not solenoid is bad. This would have nothing to do with the other issues you mentioned. Check ground wires too.

The horn relay will not interrupt positive connection unless corrosion/loose wire.

[Donald H.]

[Donald H.]

[Donald H.]

Re: 67 electrical issue

Is the ground to the battery good? Did you load test the battery?

[Richard G.]

Re: 67 electrical issue

With the assumption that the battery is good;
It sounds like a bad connection. A voltage drop test will help identify it.
My guess is with the headlight on you have less than 12 volts at the load.
You could easily measure it, inside the cab, at the 40A circuit breaker if you would like to prove it.
It is common for 12 volt systems to have the voltage but not the amperage capacity to function.

Turn on the lights (This test always requires the system to have a load on it)
Put one leg of the volt meter on the center of the battery terminal and the other meter leg on the clamp. Read the voltage. If it is less than 1 volt move on to the other terminal and do the same thing.
You are looking for a bad connection between the clamp and battery post with this test.
A very likely source of voltage drop or resistance.
If this passed do the same test (lights still on) between the batter and the cable end where it attaches to the starter. (positive)
This checks the cable's integrity.
Do the same thing for the negative, battery post and a good ground on the block. still less than one volt? Move on to a good frame connection and check for less than one volt again. This proves the block to frame ground.
If all of these measurements are less than one or two volts you have proved the battery connections good. This test can identify very low resistance values that are not measurable using the ohm side of a multi-meter.
You can use this test to other wires. Even works across fuses (from one side of the fuse to the other)
If you need a better explanation of why this works Google it. You will find some great explanations with the math to explain why it works.
Rick

[Ara G.]

Re: 67 electrical issue

Is the ground to the battery good? Did you load test the battery?

Showing "charged" and holding load are two different things. I learned this pulling my hair out.

[Richard G.]

Re: 67 electrical issue

No there isn't a good volt/Ohm meter method. Only a load test or some of the modern testers use sophisticated testing will work.
The easy method it to pull the battery and have it tested. Many auto parts stores can do it.

[Donald H.]

Re: 67 electrical issue

It was the battery. I bought an inexpensive load tester ($22 at Harbor Freight) and my battery failed miserably. Under the 100 amp load it dropped to almost zero volts.

Replaced the battery and all is good again.

[Joe R.]

Re: 67 electrical issue

Are you sure it was not the ground?

JR

[Donald H.]

Re: 67 electrical issue

Are you sure it was not the ground?

JR

[Joe R.]

Re: 67 electrical issue


And yes, this is a perfect example of what I was talking about! In my statement I was trying to be facetious but some took it for fact.

JR