1948 Oldsmobile 6 Volt Issues

[57j2olds]

Hello,

I had 2 issues over the weekend.

1. I drove the car for the first time at night. So for some reason my turn signals do not work when my headlights are on. Push headlight switch in and they start blinking. Any ideas where I need to start? I'm thinking bad HL switch?

2. My dome light was staying lit all the time Saturday (first time it has happened). I pulled the lens off and started to remove the base. As soon as I started to loosen the metal dome base, the bulb went off. So I proceeded to remove the base in it's entirety. Couldn't see anything except the old wires. 

I went to re-install the base and got zapped...saw a spark from dome lamp base to the screw I was installing and the base instantly turned red hot.  

Pull the battery cable quickly as to not have roasted Olds for dinner.

Thanks

[joe_padavano]

7 hours ago, 57j2olds said:

1. I drove the car for the first time at night. So for some reason my turn signals do not work when my headlights are on. Push headlight switch in and they start blinking. Any ideas where I need to start? I'm thinking bad HL switch?

The 1154 bulbs used in the park/tail/turn signal applications have two filaments and a common ground. When the ground goes bad, the turn signals ground through the park/tail circuit. This works fine with the lights off. Once you put the lights on, there is full battery voltage on those lamps, not ground. That's why they don't work with the lights on. Verify the grounds at the park/turn sockets before replacing anything.

Edited October 31, 2022 by joe_padavano (see edit history)

[JACK M]

Most electrical issues are groundless.

[joe_padavano]

4 minutes ago, JACK M said:

Most electrical issues are groundless.

[Oldtech]

Dome lights generally have a hot wire and the switch is on the ground side so... hot all the time at the socket. You may need a repair or just touched the hot to ground. Likely old insulation cracked or gone.  

[57j2olds]

1 hour ago, Oldtech said:

Dome lights generally have a hot wire and the switch is on the ground side so... hot all the time at the socket. You may need a repair or just touched the hot to ground. Likely old insulation cracked or gone.  

Thanks for the info. Yes, the insulation is very hard and cracking/fraying on the dome lamp. I taped it the best I could. Guess that's why the guy left it all unplugged.

 

Also - I did not mention the fact that the dome lamp works when you open the doors, however the hand switch on it does not work. 

 

2. Signal issue - I do have front passenger parking lamp that does not work. Maybe the ground issue? All bulbs are correct 6 Volt.

 

 

Edited October 31, 2022 by 57j2olds (see edit history)

[TTR]

"1948 Oldsmobile 6 Volt Issues"

 

3 hours ago, joe_padavano said:

Once you put the lights on, there is 12V on those lamps, not ground. That's why they don't work with the lights on.

???

[joe_padavano]

48 minutes ago, TTR said:

"1948 Oldsmobile 6 Volt Issues"

 

???

Sorry, typo on my part. I'm too used to answering this same question for newer GMs. I edited my earlier response.

Edited October 31, 2022 by joe_padavano (see edit history)

[Gary56]

How can I make the head lights brighter without convert to 12 volt.

[Frank DuVal]

Good grounds. Good ground cable from the battery terminal to ground. Good connections inside the dimmer switch (some can be opened and cleaned, others only replaced). Good connections inside the headlamp switch. Good wiring and connections everywhere else. With 6 volt system, they say cleanliness is next to godliness. 

[Oldtech]

Grounds may need to be added. The battery should be grounded to the engine, but from there there should be a ground strap to the frame AND to the body.  But fenders or other bolt on parts may not have a good electrical connection to the body, so it never hurts to make a dedicated ground point or strap to these parts. Lights are likely just grounded to the inner fender.  I've had Tail light issues on trucks many times that the cause was the bed not grounding. 

 

Edited November 1, 2022 by Oldtech (see edit history)

[Akstraw]

A multimeter can be your best friend in answering some of your questions. They are not expensive; I even see Harbor Freight giving them away from time to time.  For example, if dim headlights are in question,

 

I would begin by measuring the actual voltage, first at the battery, then at the socket.  It should be on the order of 6.8 volts or so in both places.  A low battery can cause dim headlights.

 

Then I would measure the resistance between the light socket and the battery clamp of both the hot and ground sides of the circuit.  You can do this with the battery disconnected, but with the headlight switch 'on'.  In a perfect world, you will have no resistance.  If you measure some resistance, then you can start isolating parts of the circuit (switch, fuse, wire runs, connections) to find the origin of that resistance.  While I agree that grounding is a likely issue, having actual data could be useful prior to doing alot of work to add or improve grounds at random.

 

A last thought on headlamps; Even when new, the lights on your '48 Olds would not have been as bright as those on your current daily driver.  You might get somewhat of an improvement over the original by using halogen sealed beam bulbs, if you don't already.   If you are not sure about the bulb or circuit, connect a bulb directly to the battery, and then compare brightness to one installed on the car.

 

I hope that helps.  Good luck!

 

[57j2olds]

18 hours ago, 57j2olds said:

 

My headlights are fine on my 48. That was another poster. 

 

I dont think my battery ground goes to my motor. I think it goes to my fender. I'll check tonight. Should I still run one to my motor?

 

Do you think (turn signal issue) that due to the fact that my front PS parking lamp wont work has something to do with this ground issue?

 

Thanks

 

 

 

[TTR]

First, before proceeding further, make sure you have and study (enough to understand basics of) the electrical section and wiring diagrams of a factory service manual for your car.

 

Then, even with his initial minor voltage mixup, Mr. Padavano’s suggestion seems like a good place to start the diagnostics and process of elimination.

 

P.S. As suggested by several members, good/strong ground to engine, frame and every body panel housing any electrical components is the most vital thing in automotive wiring,

although many British cars/trucks, especially those with wood framed bodies, require ground to be separately brought to each individual component.

 

Edited November 1, 2022 by TTR (see edit history)

[JACK M]

1 hour ago, 57j2olds said:

 

I dont think my battery ground goes to my motor. I think it goes to my fender.

Ground to the engine. Ground the engine to the chassis. Ground from the engine to the body.

As noted, often fenders and/or individual sockets need dedicated grounds.

I cannot stress enough about proper grounding.

Make yourself a fairly long jumper wire and make temporary grounds, you might be surprised how weak some of your accessories are grounded.

[57j2olds]

Thanks guys. 

 

Looks like I have some work this week. I'll need to buy some grounding straps. 

[Bloo]

4 hours ago, 57j2olds said:

I dont think my battery ground goes to my motor. I think it goes to my fender. I'll check tonight. Should I still run one to my motor?

The primary thing with battery cables is that there is a good path through nice big cables from the battery to the starter.

 

On some cars the battery ground cable goes directly to the engine/transmission. In cases where that is not true, there needs to be a third battery cable or strap. It goes from whatever the battery cable connected to on over to the engine/transmission.

 

Example: On a 1936 Pontiac, the ground cable goes to the frame. There is a big heavy ground strap from the frame over to the engine/transmission to complete the circuit.

 

You mentioned a fender. If the Olds is supposed to have the cable connected to the body like that, then there should be a big strap or cable from the body to the engine/transmission. All connections need to be clean and tight. Think of an electrical circuit as a big circle, and for a starter that is 1) from the battery to the starter with a cable, 2) from the starter case mounting to the bellhousing or block, 3) from the bellhousing or block back to the battery, either through one cable, or cable-frame-cable, or cable-body-cable. The cables and connections need to be equally good all the way around the circle from the battery to the starter and back.

 

I hope someone in this thread with Olds knowledge can tell us whether your negative cable is connected in the right spot. If not, you should move it where it belongs.

 

Starter cables (and grounds) as I have described need to be a lot bigger for 6v cars. 2/0 (00) cable is usually recommended, or equivalent to that if we are talking about straps, but in any event bigger than the 4 Gauge usually used on 12V cars. Stores that sell parts for tractors should have 6v appropriate cable, as 6v tractors are still common.

 

Edited November 1, 2022 by Bloo (see edit history)

[Doctor's Pontiac]

2 hours ago, Bloo said:

The primary thing with battery cables is that there is a good path through nice big cables from the battery to the starter.

 

On some cars the battery ground cable goes directly to the engine/transmission. In cases where that is not true, there needs to be a third battery cable or strap. It goes from whatever the battery cable connected to on over to the engine/transmission......

 

I hope someone in this thread with Olds knowledge can tell us whether your negative cable is connected in the right spot. If not, you should move it where it belongs.

 

Starter cables (and grounds) as I have described need to be a lot bigger for 6v cars. 2/0 (00) cable is usually recommended, or equivalent to that if we are talking about straps, but in any event bigger than the 4 Gauge usually used on 12V cars. Stores that sell parts for tractors should have 6v appropriate cable, as 6v tractors are still common.

 

The 41 Oldsmobile has the ground cable from the battery to the front of the starter motor where there is a large bolt to attach the ring from the cable. Here is the wiring diagram to confirm it. Yours is a 48 model and may be different. You need to find a wiring diagram to make sure. Shop Manuals typically have one. 

 

 

 

In reference to the gauge/size of battery cables, you may find helpful to read my recent post in this forum regarding problems to start my car which was resolved with help of several knowledgeable Forum members by getting the correct cable gauge, a 00 (also called 2/0).  The post name is "Ignition switch wiring connection of 41 Oldsmobile".

 

 

 

[57j2olds]

Took a quick look tonight and my negative cable goes to my starter only. 

 

Do I need to run one to the frame too?

[Doctor's Pontiac]

The battery ground cable should be cleaned and connected tightly on both ends but your issue is localized to parking lights and turn signals. Those are the sites where poor ground may be causing the problem and not a systemic fault attributable to the battery ground. After cleaning and reconnecting the battery ground cable,  remove the bulbs and check if you get volts at the socket and if you do then add a jumper wire with a simple alligator clamp from the socket to a good ground on the body or frame and test if lights work.  If they do, it means poor ground connection at the socket. I did that way and helped to fix tail lights. 

[57j2olds]

Update:- 

 

I installed a new ground strap from the battery to the engine block and one from the block to the firewall. 

 

Right turn signals are working now with the headlights on. Left still is NOT. More work on socket grounds I think. 

 

Fixed dome lamp wiring issues. Insulation was bad...grounding out on steel roof. Light goes on when door are open. However manual switch is not working. Not the end of the world. I assume the switch is bad. 

 

Sooo I decided to tackle the dealer installed yellow fog lamps made by Unity.

 

They were not hooked up (No clue when the last time they were) so I ran battery power directly to one of them and it came on for 5 seconds and then blew. 

 

My question is - How were they originally wired to be turned on and off? Was there a separate switch? Since you would not use them 100% of the time I assume that they would not be wired to headlight switch. 

 

Thanks

 

 

[EmTee]

23 hours ago, 57j2olds said:

Was there a separate switch? Since you would not use them 100% of the time I assume that they would not be wired to headlight switch. 

Yes, separate switch.