replacing lighting coil

HoosierDeereMan · Post by **HoosierDeereMan** » Tue Feb 05, 2008 1:48 am

Brian,

I found this in my Cylmer manual.

On electric start models, the lights are powered by the battery. The lighting coil is used to charge the battery.
1. Disconnect wires to the circuit breaker on the battery box and connect a DC ammeter.
2. Block up the track securely so engine can run safely at operating speeds. Run engine at 6,000-7,000 rpm. On 1974 and 75 snowmobiles, output should be 2-4 amps with the lights off and 3-5 amps with lights on.
3. If output is not specified, disconnect voltage regulator and recheck. If output increases, voltage regulator is defective. If output does not increase, check key switch,rectifier, and wiring. If still no output is indicated, the lighting coil could be defective.
4. Disconnect electric start and reinstall manual start coupler.

It jumps back to the manual start segment in the book.

The voltage regulator will malfunction in two ways: an "open" condition will cause all lights to burn out ( at engine speeds over idling); and a "shorted" condition will prevent any lights from lighting.
1. You already have the sled blocked up.
2. Install a new tail light bulb.
3. With the light off start and run the engine to appoximately 6,000 rpm; then, apply the brake. Taillight will burn out immediately if voltage regulator is faulty. If it doesn't votage regulator is working properly.
4. Disconnect voltage regulator from system.
Caution: When checking headlight intensity with voltage regulator disconnected, run engine at idle speed only. Lighting system is unregulated and a faster engine speed will cause lighting coil output to burn out the lights.
5. Start and run the engine at idle speed. Turn on lights. If headlight lights and has good brilliance, lighting coil is functioning. If headlight is dim or will not light at all, lighting coil is malfunctioning and must be replaced. Headlight intensity should remain uniform at all engine speeds.

HoosierDeereMan · Post by **HoosierDeereMan** » Tue Feb 05, 2008 2:03 am

Rectifier test on 73-75 models.

Excuse my crude diagram but you get the idea.

TOP OF RECTIFIER
I (AC +) I DC

I DC I (AC -)

1. Disconnect 4 connectors from the rectifier. A diode exists between each of the 4 terminals in the rectifier. Test the 4 diodes one at a time by connecting a test light to 2 adjacent terminals.
2. Test with leads on top 2 terminals;2 bottom terminals, and 2 right terminals. Reverse terminal contacts in each test set-up. Do not test terminals in a diagonal pattern.
3. With leads connected one way, test light should light. With leads reversed, a high resistance or open condition should be indicated. Repeat the steps for the other 3 diodes. Replace if defective.

HoosierDeereMan · Post by **HoosierDeereMan** » Tue Feb 05, 2008 2:13 am

Ignition switch test.

D.........E

................A

C.........B

Position/Closed/Open

Off........A & D.....B,C,E
On........C & E......A,B,D
Start.....B & E......A,C,D

Again sorry for the crude diagrams. I hope this helps.

400brian · Post by **400brian** » Tue Feb 05, 2008 5:14 am

Had a measure of success tonight.

I had it in my head that both yellow wires coming off the lighting coil should show current. JDT pointed out that one side is the ground. I had been pondering this all day. Tonight, as I was having a sandwich before going to milk cows, I studied the wiring diagram. After a few moments I yelled: URETHRA! I HAVE IT!

Last night I noted that the top left hand connector in the plug showed around 20 volts AC. According to the diagram, a brown wire goes into the connector as the hot wire, and a brown / white wire is the ground. It occured to me that if I had switched the wires when I spliced in the new lighting coil, the hot wire would be connected to a ground! ( I thought I had kept track of which wire went where, but they are both yellow......)

Tonight I went over to the shop and looked...., and sure enough, the ground wire was in the top left side of the plug. I swapped the wires around in the plug, fired it up, and I had lights.

I switched it over to the e-start system, took a look at the ammeter, and saw slight charging with the lights off, and discharging with the lights on.

So it's still not 100%. Suppose my new V reg I just installed is not so great?

But hey! I've got lights, and I didn't have to tear the engine apart again!

Thanks for the input guys, I appreciate it.

JDT · Post by **JDT** » Tue Feb 05, 2008 5:57 pm

So every light now works ?

Does the tach read also read correctly?

And the only problem is that it is discharging with light switch in the on position?

Can you measure the voltage with both switch on and off please.

400brian · Post by **400brian** » Tue Feb 05, 2008 7:09 pm

The only thing I have noticed not to be working is the brake light. I checked the bulb, it seems good, so I'm not sure what the issue is there.

Tach is reading normal now.

Plan for tonight is to check the charging rate with the V. reg disconected.
I can check the voltage. Probably easiest at the rectifier.

I didn't see much, if any change in the charging rate with an increase in RPM.

400brian · Post by **400brian** » Wed Feb 06, 2008 5:51 am

I saw no change with V. reg disconected.

Voltage reading at brown wire at rectifier conection:

Lights off - 10v

Lights on - 5v

I seem to have a much higher reading at the orange wire 20-30v, but I didn't know what to make of that, or if it was AC or DC. Didn't have the SM in the shop, and I'm getting punchy with all these late night wrenching sessions.

JDT · Post by **JDT** » Wed Feb 06, 2008 9:40 am

Reading on the brown wire is AC. Were did you have teh other lead hook to when you took this reading?

Reading on the orange wire is DC. 20 volts at this point with the regulator disconnected would be normal.
Retest at this point with regulator hook up. Should be 9-10 VDC at idle and 13-14 at high RPM.

400brian · Post by **400brian** » Wed Feb 06, 2008 12:24 pm

Meter hooked to brown wire and batt ground ( which grounds to engine )

Need to recheck the orange wire reading.