Electric Starter Problem

michaelpthompson

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OK, so I searched the Forum but didn't find an answer to this specific problem. 1975 XS650B. When I got it, the electric starter didn't work. I'd press the button and hear a click, but that's all. Laid it on a crate on its side, thinking to take a look at the starter. Turns out I could have saved the trouble, but now I have a completely different problem.
I hooked a positive jumper cable to the nut that holds the starter cable onto the relay, and put the negative on ground. When I hook up the other end of the positive cable to the batter, the starter motor turns. So I took off the jumpers and clicked the button again so I could listen for the location of the click. But now it doesn't click. Change position of key, on-off switch, engine kill switch, no sound in any position. Put the jumpers back on and it's the same. Don't even have to connect the negative end to the battery, only the positive, and the starter motor turns.
I'm thinking probably the relay, but from what I've learned on this forum, it may be more complicated than that. Any advice appreciated. (Other than RTFM, I'm working on that.)
Thanks.
 
It has all the signs of a very weak/dead battery.
How old is the battery? What is its voltage? Put the battery on a bench charger for about 8 to 10 hours, and then try again.

After you have done the above, connect your VOM to read battery voltage on the 20 volt scale. Watch the VOM as you press the start PB. If it momentarily drops to less than 10 volts, your battery is dead.

Edit: When I read "jumper cable", I thought you meant jumper cables from your car or truck. My bad. Your battery is good.
 
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Battery is ok since jumping works. suspect relay. Or wiring incl button. Jumper to relay instead of starter to test relay and relay wiring to starter .
 
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Battery is brand new and has been on a battery tender for a couple of months now. Also, I looked over the wiring diagram and now I realize why the starter turns with only the positive cable connected; the starter and the battery are both grounded all the time. So it definitely sounds like a relay problem or not getting juice to the relay. I'll get my big, strong son to set it back upright and poke around in that area.
 
Once in a while, the safety relay beside the solenoid (someone will chime in with the right name) has to come apart and be cleaned to make the starter button work.
 
The starter button grounds the thin blue white wire from the relay, the thin red white wire at the relay should have battery voltage when the key is on. Jumping the two big relay terminals with screwdriver should spin the starter.
 
On your 75 it doesn't have all the safety stuff the 80 up bikes had. The only "safety" thing it has is the safety relay. It is mounted under the left side cover, a small rectangular box with 4 wires. Red, red/white, yellow and black. Red is power in from the key switch. Red/white is power out to ignition and starter relay. Yellow is from the alternator, it sends voltage to the safety relay when the alternator starts making power. Black is ground. This safety relay protects the gears and crossover shaft between the starter and engine.
When you first turn on the key power flows through the safety relay to the starter relay. When you start the bike and the alternator starts producing power the relay trips and cuts off the power to the starter relay. This prevents the starter from working as long as the engine is running.
Now on to the rest. You already tested the starter by jumping from battery positive to the starter cable lug. Starter works.
To test the relay you need to check voltages at the battery , key on engine stop switch on. Use this voltage as a reference to compare to. Now at the starter relay check the voltage on the red/white wire. It should read very close to your reference voltage, if not you need to trace back along this red/white wire to find and fix the problem.
Once you have good voltage on the red/white wire jumper from the blue/white wire to ground. This completes the circuit and trips the relay to send full battery voltage to the starter. If the starter works this way your ground path needs a look see. The ground path on your 75 is the blue/white wire, it runs up to the start button, when pressed the start button grounds the b/w wire to the switch housing. The switch housing grounds to the handle bars. Oh, just a thought,does the horn work? The horn uses a similar ground path, the pink wire from the horn to the button, grounds to bars. If the horn works then the ground path for the bars is ok. If not you need to continue along the ground path to find the issue. The bars are grounded by a black wire hooked under on of the handle bar riser mount bolts, under the upper tree. This wire runs around to one of the tree clamp bolts the hold the fork tubes in the trees. From there is parhg goes through the trees, steering head bearings to the frame.
Not the best way to do this but it works. On later bikes they added a ground wire from the left side switch housing to down into the headlight bucket to the harness ground. I might suggest doing something similar. Instead on hooking the wire from the riser bolt to the clamp bolt. I would splice into that wire and add enough black wire to reach back under the tank and hook it under a coil mount bolt.
If your starter relay proves to be bad get a stock relay from an XS650, other will function ok but not fit where the stock on does.
Leo
 
Thanks Leo, I will work through that tomorrow. Got it back upright, and discovered that now none of the lights come on. Before, the headlight and brake lights worked, now they don't. So I guess the button and relay are the most likely culprits. Got to figure out where it's losing voltage. Still thanking everybody for all the sage advice.
 
May have blown your fuse. Stock that year only had one 20 amp main fuse.
Blown fuse you get no power to the relays.
leo
 
Bingo! Good thing I still have a collection of old-style tubular fuses.
IMG_6062.JPG

Now I'm back to where I was. I know the starter motor is ok because when I jumped it, it would turn. And my button must be all right because otherwise, there would be no click at the relay when I pressed it. So it must be the relay, right?
 
Ok, just because you hear a doesn't mean the button is ok. The contacts on the button itself can be corroded a small amount and not carry enough to trip the relay, thus the click.
Have you checked the voltage at the battery and on the red/white wire at the starter relay? If the red/white wire is getting proper voltage try a jumper from the blue/white wire to ground. As I talked about a bit ago.
Do these checks and report back your results.
Leo
 
Remove clean replace battery to frame ground strap. (always) same with positive wire from battery to relay. Watch for corroded, broken wires at the crimp on connectors.
 
OK, got a free multimeter from Harbor Freight with any purchase and a coupon. No joy at the red/white wire, or the blue/white wire. Still get a click at the relay when I press the starter button. Somebody has seriously messed with these wires, but it looks like the red/white wire goes into a bundle that goes underneath somewhere. Any guidance on how to trace that would be helpful. BTW, in response to another question, no the horn doesn't work either..
IMG_6080.JPG
 
Once in a while, the safety relay beside the solenoid (someone will chime in with the right name) has to come apart and be cleaned to make the starter button work.

It's called the Starter Safety Relay (SSR) and it's important that it be there and that it is working properly because it prevents your starter from engaging if thenengine is running.

Anyhow - the fact that your horn does not work could mean that your handlebars are not grounded properly. The handlebars MUST be grounded for both the starter button and the horn to work. To check this - put your multimeter on the lowest "Ohms" scale and check for a zero reading with one lead on the battery negative terminal and the other on the handlebar. If the meter reads zero (which it should) - then there is a problem with your horn wiring as well as with the starter.

The other thing is: I would get a modern blade fuse holder with a little wiring pigtail and replace that crummy old glass fuse holder and fuse. The glass fuses are fragile and they're becoming a little hard to find.

Stick at it - you'll get there.

Pete
 
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OK, this is like chasing a ghost. Just tried it again. Now the horn works, and when I turn on the ignition, the brake light stays on constant. I'll check the grounding between the handlebars and the battery.
 
Brake light is a different issue. That may be related to the rear brake light switch down behind you right foot peg mount. It's a little mechanical plunger-looking thingy with a spring that goes to the brake pedal lever.
 
Yeah, turned out the brake light switch was a bit loose. If I wiggle the rear brake lever, the light goes out.

Weird things coming up on the diagnosis though. XSLeo said check the red/white wire. No voltage there when pressing the button. So I put a jumper from the positive battery terminal to where the red/white wire is attached to the relay. Sparks and a click (but not the same click as when I press the starter button), and the wire gets hot, but the starter does not turn. Also jumped the blue/white wire to ground. Nothing at all. Sounds like I really need to look at the grounding, but this makes me wonder. Any further hints appreciated, as always..

Edit: When I read "jumper cable", I thought you meant jumper cables from your car or truck. My bad. Your battery is good.

LOL, actually it WAS jumper cables from my car. Since I was running full amperage from the battery to the starter, I didn't want to use some weak little wire, so I actually used jumper cables from my car to test this. But yes, the battery is good. Reads 14+ volts on the multimeter.
 
The other thing is: I would get a modern blade fuse holder with a little wiring pigtail and replace that crummy old glass fuse holder and fuse. The glass fuses are fragile and they're becoming a little hard to find.

Sounds like a good plan. I was just in my local Radio Shack and discovered they're going out of business. They had big clearance sales on everything, including drawers full of glass fuses. Unfortunately, the 20-amp was already sold out, or I would have bought what they had.
 
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