[fyrffytr1]

There are only three wires that hook to the switch but I don't know which one goes where. There are no markings on the back of the switch. I figure one wire is a hot one from the battery and one goes to the starter button maybe and then there's the third wire that is a small gauge one but I don't know where it goes.
Does anyone here have a schematic for the switch?

[Stuart]

Here's a 1949 Pontiac wiring diagram, if it's not the same as 1950 it's probably pretty close. http://chevy.oldcarmanualproject.com.../49psn006.html

[fyrffytr1]

That would help if I knew what lug each wire went to on the switch. The wires were hooked to the old switch but the part they were hooked to was no longer in the switch. It was hanging free under the dash. When I touched it two of the wires fell off.

[Bill Hanlon]

How many position does the key have? Just on and off, or off/accessory/on?

The schematic that Stuart referenced shows a red wire attached to the BAT terminal on the switch going to the battery. Most likely it doesn't actually connect directly to the battery, but more likely to the top big lug on the starter solenoid.

The schematic that Stuart referenced shows a black wire attached to the IGN terminal on the switch going to the + terminal on the ignition coil.

The schematic that Stuart referenced shows three wires attached to the ACC terminal on the switch going to
a. the gas gauge
b. the temp gauge
c. the fuse box
The colors on these 3 wires are hard to identify from the schematic. It appears that at least one of them is black with an orange stripe. I can't read the other wire colors.

[pfilean]

The wires on a 50 are likely the old braided cover type and the colors are hard to see.. Only some if the threads in the braiding and faded by now but look closely.

The switch probably has some letters cast into the plastic to identify the terminals. But if not think of it this way. With the switch in the off position you will not have continuity between any two terminals. Turn to the accessory position and there will be continuity between the Bat terminal and the Acc terminal but not the Ign terminal. So you will have identified which are the Bat and Acc terminals. The third must be the Ign terminal. There is probably one of the terminals that was intended to be the Bat terminal but if you get the proper continuity does it really matter. If the wires are interchanged between the intended Bat and Acc terminals you may get the same function anyway. If you had a switch with start function or multiple Ign terminals you would have a more complex problem

[stevep]

A Pontiac ignition switch up to 1952 has 2 positions, on and off. It has a starter button.

[Stuart]

Originally Posted by stevep

A Pontiac ignition switch up to 1952 has 2 positions, on and off. It has a starter button.

That wiring diagram shows an accessory terminal, but if I understand correctly there isn't a separate 'accessory' position for the key? That terminal is only connected to power when the key is in the 'on position'?

It's been too many years since I drove a car that old, so my memory is rusty.

[Bill Hanlon]

Sounds like the ignition switch in my '52 GMC truck. If you turn my key VERY slowly from off to on the ACC terminal makes contact slightly before the IGN gets power. The difference between the two is probably less than 5 degrees, but I can get the radio to come on without powering up the coil.

[fyrffytr1]

Originally Posted by Bill Hanlon

Sounds like the ignition switch in my '52 GMC truck. If you turn my key VERY slowly from off to on the ACC terminal makes contact slightly before the IGN gets power. The difference between the two is probably less than 5 degrees, but I can get the radio to come on without powering up the coil.

I will have to try that. I was finally able to figure the switch out by metering it to find what lug was the hot one. Battery from the starter to one terminal, ignition to one and accessories to the third. The ignition wire runs from the switch to the ammeter and headlights before reaching the starter button.
There are no markings on the back of the switch and all the wires look the same dirty tan color to me.
Now, I can't get the starter button to work. I think it is bad because I get voltage to both sides of it with the key on. Key off there is no voltage. I can jump the starter to make the motor turn over and that is all I wanted to accomplish right now.

[Bill Hanlon]

The starter switch and the horn relay are both fed from the "battery" side of the ammeter. They should both be hot any time the battery is hooked up. Both should work with the key off, but of course the engine would just turn over without starting because no power is available to the coil without the key on.

There shouldn't be

Originally Posted by fyrffytr1

voltage to both sides of it with the key on

unless your push button switch is bad (internally shorted) and in that case the starter should be spinning all the time IF (big if) the wiring is connected as shown in the schematic.

[fyrffytr1]

Well, when I took the switch out it fell apart in my hand so I figure it was bad, BUT, I have voltage to both wires with the switch on. I may need to revisit the switch wiring, Could I have the ignition and accessory legs hooked up backwards? When I turn the key on the fuel gauge works. The only way I can get the motor to turn over is by jumping the solenoid with a screwdriver from the small lug to the ground lug. A remote starter switch will not even work. Could the starter solenoid be bad?

[Stuart]

If the only way it will turn over is by jumping the solenoid, I'd guess the solenoid is bad.

[fyrffytr1]

Originally Posted by Stuart

If the only way it will turn over is by jumping the solenoid, I'd guess the solenoid is bad.

I had the starter tested at work and while it passed it was drawing excessive amperage so I took it apart and cleaned it up. When I tested it again it passed with flying colors.
I just feel like I still have the ignition switch hooked up wrong. Why else would there be 6 volts to either of the starter button wires with the button disconnected? And,should there be voltage to both sides of the coil with the switch on?

[Bill Hanlon]

I question your statement "The only way I can get the motor to turn over is by jumping the solenoid with a screwdriver from the small lug to the ground lug." What you are calling the "ground lug" is more likely to be the battery connection to the solenoid. When you use a screwdriver to jump the "small lug" on the solenoid to the battery connection you are energizing the solenoid in the same way that the starter push button SHOULD be doing its job.

According to the schematic, there should be battery voltage on one of the starter button wires, but not the other starter button wire, no matter if the ignition switch is in the on or the off position.

With the ignition switch on AND without the engine running there will be voltage on both the + and the - terminals of the coil if the points are open. If the points are closed there will only voltage on the + terminal.

[fyrffytr1]

Here is a picture of the starter as it sits now. I can jump it by connecting the small lug to the large one beneath it. Also, the points are closed but there is voltage on both sides of the coil with the switch on. I think the ignition switch is hooked up wrong. I'll play with it some more tomorrow after work.

[Bill Hanlon]

Originally Posted by fyrffytr1

Here is a picture of the starter as it sits now. I can jump it by connecting the small lug to the large one beneath it.

Use your meter to see if there is 6 V from the small lug to ground without pressing the starter button. There should NOT be power there until the starter button is pushed.

Use your meter to see if there is 6 V from the large lug to ground without pressing the starter button. There should NOT be power there until the starter button is pushed.

The large lug is power into the starter from the solenoid.

Originally Posted by fyrffytr1

the points are closed but there is voltage on both sides of the coil with the switch on.

Closed points SHOULD be providing ground to the - terminal of the coil. Either the wire from - coil to the distributor is broken or not connected to the points, the points are so dirty that they are not conducting when they are close or (some distributors, I don't know about 50 Pontiacs) the ground wire under the plate that the points mount on is not connected to ground.

[fyrffytr1]

Bill, Thanks for the help. I will try the metering this weekend. I plan on picking up another car tomorrow but, if I don't I will meter the starter and get back with the results.

[fyrffytr1]

Worked late so I didn't go after the other project car.
I did meter the starter and found that with the key on there is 6 volts to the small lug. Key off there is no voltage.
With the key on there is no voltage to the large lug. With the starter button wires jumped( the starter button fell apart when I took it out to check it) there is still no voltage. Bad solenoid?
I didn't have time to check the points. Could they affect the starter circuit?

[Bill Hanlon]

Originally Posted by fyrffytr1

I did meter the starter and found that with the key on there is 6 volts to the small lug. Key off there is no voltage.

Not right. Disconnect the wire from the small lug on the solenoid and do the test again checking both the small lug and the disconnected wire. The schematic shows that the only thing that connects to that small lug on the solenoid is the starter button's wire that should only have 6 volts on it while you are pressing the button.

Originally Posted by fyrffytr1

With the key on there is no voltage to the large lug.

Normal.

Originally Posted by fyrffytr1

With the starter button wires jumped( the starter button fell apart when I took it out to check it) there is still no voltage. Bad solenoid?

Maybe, but first, is there 6 volts available on the OTHER large terminal on the solenoid?.

[fyrffytr1]

There is six volts to the other large lug all the time.