side marker light on '49 8N

Ken C. · Aug 31, 2015

I just made the 6 to 12 volt (neg. grd.) conversion, using the Delco 10SI alternator. After connecting the #1 spade terminal on the alternator thru the side marker (5 watt) light, & on to the ignition switch (accessory side), the light is on with the key OFF, & goes OUT with the key on. It was suggested to me that my key switch is grounded when in the OFF position causing the light to be ON. Is this normal on this tractor? Your help is appreciated!
Thanks, Ken C.

Bob · Aug 31, 2015

"It was suggested to me that my key switch is grounded when in the OFF position causing the light to be ON. Is this normal on this tractor?"

No, but having an ignition switch with an "accessory" terminal is not "normal" for an old "N", either! Someone has added a non-OEM-style switch (which should be just fine).

Are both terminals on the "side marker light" isolated from chassis ground and only connected to the # 1 alternator terminal and the ignition switch?

Is there anything else connected to the "accessory" terminal on the ignition switch?

Is the "hot" lead (battery power) correctly connected to the "batt" terminal on the switch?

With a test light, (ignition "OFF") determine if the "marker light" is getting power from the alt or the switch and post back with that info.

souNdguy · Aug 31, 2015

ditto what bob said.

there is more to this story that you aren't telling us.

JMOR · Aug 31, 2015

(quoted from post at 12:06:14 08/31/15) I just made the 6 to 12 volt (neg. grd.) conversion, using the Delco 10SI alternator. After connecting the #1 spade terminal on the alternator thru the side marker (5 watt) light, & on to the ignition switch (accessory side), the light is on with the key OFF, & goes OUT with the key on. It was suggested to me that my key switch is grounded when in the OFF position causing the light to be ON. Is this normal on this tractor? Your help is appreciated!
Thanks, Ken C.

ou don't by any chance have a one wire 10SI alternator do you?

JMOR · Aug 31, 2015

(quoted from post at 12:06:14 08/31/15) I just made the 6 to 12 volt (neg. grd.) conversion, using the Delco 10SI alternator. After connecting the #1 spade terminal on the alternator thru the side marker (5 watt) light, & on to the ignition switch (accessory side), the light is on with the key OFF, & goes OUT with the key on. It was suggested to me that my key switch is grounded when in the OFF position causing the light to be ON. Is this normal on this tractor? Your help is appreciated!
Thanks, Ken C.

ou don't by any chance have a one wire 10SI alternator do you?

Ken C. · Aug 31, 2015

First, thanks, I hope this helps. Yes, it is a single wire alternator. In the photo @ the top left lug, (left to right) pink is + coil wire (coil is EI coil). Orange is volt meter, & frayed grey is key switch. Bottom lug, left to right: orange BATT main wire from alternator, grey is other key switch, & other orange is from starter solenoid (+ battery cable).The blue wire (disconnected) is to the side marker light. This light is not grounded anywhere, but will light if grounded.
Ken C.

<image src="http://forums.yesterdaystractors.com/photos/mvphoto26828.jpg"/>

JMOR · Aug 31, 2015

(quoted from post at 18:32:48 08/31/15) First, thanks, I hope this helps. Yes, it is a single wire alternator. In the photo @ the top left lug, (left to right) pink is + coil wire (coil is EI coil). Orange is volt meter, & frayed grey is key switch. Bottom lug, left to right: orange BATT main wire from alternator, grey is other key switch, & other orange is from starter solenoid (+ battery cable).The blue wire (disconnected) is to the side marker light. This light is not grounded anywhere, but will light if grounded.
Ken C.

<image src="http://forums.yesterdaystractors.com/photos/mvphoto26828.jpg"/>

here are at least a half dozen different regulators used in one wire alternators. Some can be connected with the charge lamp, as if not single wire & some can not. Yours may be the latter.

tractorguy2 · Aug 31, 2015

I wouldn't think a one wire would need the marker light.

Where do the wires on your volt meter go?

Ken C. · Aug 31, 2015

Yes, I do have a single wire Delco SI10. Is this alternator wired or built so that, with the key in the off position, current cannot flow back thru the alternator and drain the battery?
Thanks, Ken C.

JMOR · Sep 1, 2015

(quoted from post at 23:55:13 08/31/15) Yes, I do have a single wire Delco SI10. Is this alternator wired or built so that, with the key in the off position, current cannot flow back thru the alternator and drain the battery?
Thanks, Ken C.

es, on a standard 10SI, but as I said above, one wire units are different and in many variations. One in particular, the #1 spade terminal is common with the BATT stud, so is therefore at battery voltage all the time & could source power to a lamp.

Ken C. · Sep 1, 2015

Hi Bob, My key switch is original. The side marker light is isolated. Napa, where I bought the alt. said "for sure, the power source to the light is coming from the alt. See my wiring photo I posted.
Thanks, Ken

Ken C. · Sep 1, 2015

Here is a site that explains the one wire, & 3 wire SI10 Delco alternators, their advantages, & disadvantages. I was hoping to read some explanation about how the side marker light might also be useful to prevent possible back flow of juice thru the alternator & drain the battery with the key off. Is this not a concern anymore with these alternators? This article says that the side marker light is only used on 3 wire installations anyway (mine is a 1 wire), & to show alternator output or performance.
Ken C.

http://bob_skelly.home.comcast.net/~bob_skelly/alternator_conversion/wiring_alternator1.html

JMOR · Sep 1, 2015

" I was hoping to read some explanation about how the side marker light might also be useful to prevent possible back flow of juice thru the alternator & drain the battery with the key off. Is this not a concern anymore with these alternators?" That never was the concern. The concern was that when you turned the ign key off, the spinning alternator would try to power the ignition via the connection to #1 excite terminal. Solution was to block such flow with a diode or the high resistance of a small lamp (marker). No connection to #1 makes this a moot point.

side marker light on '49 8N

Ken C.

Member

Bob

Well-known Member

souNdguy

Well-known Member

JMOR

Well-known Member

JMOR

Well-known Member

Ken C.

Member

JMOR

Well-known Member

tractorguy2

Well-known Member

Ken C.

Member

JMOR

Well-known Member

Ken C.

Member

Ken C.

Member

JMOR

Well-known Member

Similar threads