continuity of light switch question JD 650

kmosabe · Jul 10, 2007

All, I am trying to track down why my headlights do not work, I started with the simple, bulbs, corrosion, loose wire etc, now I am at the switch. Not knowing what is supposed to be on since lights never on, here is my question. Based upon the switch, using the continuity tester, I have continuity between the headlights upper beam, tail lamp, and warning lights. With the low beam, I have continuity with the low beam, tail lamp and warning lights. When you have your headlights on, should the rear tail lamp and warning lights be on?

Laneman950 · Jul 11, 2007

I have a 950, seems like they would be the same. On mine the rear lights are on when the headlights are on. I have a rotary switch labeled F (field use, headlights only) W (white work light on rear) H1 (head and tail lights) H2(head and tail lights). On mine if one headlight is not installed they both won't work. I would check for voltage in addition to continuity. I know this is obvious but be sure to check the fuse panel too.

gator · Jul 11, 2007

By my 650/750 JD shop manual.
To check operation of electrical functions:
1. Turn key switch to on position. Turn light switch to each position and check all lamps that should glow.
A (all the way left) - Off.
B (first position to right)- Warning lamps.
C (next position right)- Head lamps on high beam, floodlamp, hourmeter lamp.
D (next position right)- Head lamps on high beam, tail lamp, warning lamps, hourmeter lamp.
E (last position right)- Headlamps on low beam, tail lamp and warning lamps

So the answer to your question is yes.
Have you checked the fuses? Each lamp circuit is on a seperate fuse after the switch. The high and low beam are each 15 amp. They are the top left (low beam) and middle left (high beam) fuses when looking at the fuse box.

kmosabe · Jul 11, 2007

Thanks Laneman950 and Gator, that is what I thought, Fuses were good, continuity is good, so somewhere no voltage. Will have to track down the problem. Bought the tractor from a local, guy fixed things but being a farmer, fixed them on the cheap. Wiring shot, I had to buy the correct switch key, because of the wrong type would not drive the glow plug. After installed switch key, glow plug would not work. Found out wiring ripped out to glow plug. I took off the air intake hose so I could see if the glow plug glowed, I ran a temp wire from r1 to glow plug and wire from r1 to r2, turned the new switch key to the left and yes it works, did not see it glow because I turned back the key after holding it there for about 5 seconds because the smell of burning made me concerned. I assume, if he had not used it in a long time, it is burning off the carbon, but not knowing for sure, I turned it off. Can glow plugs be cleaned?

jd110 · Jul 11, 2007

It is normal for a glow plug to smoke and or smell like something is burning when they are engaged. I assume you had the glow plug removed or had the intake hose off so you could see it. I suppose it could be cleaned, but it shouldn't be necassary. On the 650, the glow plug actually drips fuel on it when hot to start a small fire in the intake. Then when the engine is cranked, the burning fuel is drawn in the cylinder for easy starting. It is a very effective starting aid. Just be sure to never hold the glow plug engaged longer than recommended.

kmosabe · Jul 21, 2007

Well, I finally got all the electrical working with the exception of the neutral start switch and the seat switch which were disconnected. I had to buy the correct switch key, run a new wire to the glow plug which was disconnected, track down a short, and redo the wiring harness for the front lights. Personally, I probably will leave the safety switches disconnected, but was wondering if others had different opinions on if I should rewire these so I cannot start the tractor in gear or if not seated. What do others think?

Inspector507 · Jul 22, 2007

kmosabe,
Just an FYI, if you have any trouble locating parts for your 650, or for that matter any 650, 750, 850 or 950, I just found out one of our posting Yanmar dealers now has a pdf catalog of parts he can supply for your machine. Not every part is available, but quite a few.
I'm sure he'd email you a copy if interested.