short

[Guest]

Hello all. New user here. but long time suzuki owner. Have an issue with my 79 gs850 hoping someone can help save me some time.
When getting it ready for this season, one of my offspring put the battery in backwards. I get home from work and am told about this problem. so i start checking and the whole electrical system is dead. first check fuses. main is blown. replaced that and have power to everything again. but wont start.
check plugs and wires, no spark.
check points, good voltage to points.
removed battery
ohm test across main battery cables shows dead short. so I started to disconnect various harness connectors to isolate issue. found full continuity between ground and two different connectors, the headlight and turn signal wires to the fuse box. disconnected those two connectors and whole system dead again. reconnected and reinstalled battery. checked points again, and motor actually backfired while i was manually opening and closing points.
found full continuity between both sides of point faces when the points are open.
Is this just going to be a matter of following the wiring diagram until I find it, or can someone give me mystical insight or experience into where I should start?
thanks

[posplayr]

The magic is to your dilema is called binary search or divide and conquere.
It is equivalent of using the same math that creates the large combinatorial sum of doubling your options with each additional step to one of reducing your options to 1/2 at each step.

The solution is to divide the problem into relatively equal parts. First step
Use the fuse box to isolate circuits ; concentrate on one circuit at a time with the single circuit that has a fuse. Is the problem in each fuse circuit or just one?
Then proceed to divide that circuit with the fault. Next approach is to remove all divides to see if the short is in the external divides or the harness.if the harness the put ohm meter and between ground and 12v side and disconnect a connector to split the problem in 1/2. Do all testing with the battery removed.

[tom203]

"...give me mystical insight "

Be careful what you ask for! anyways, long time since I played with points but maybe your condensers are short circuited since you said

.."I found full continuity between both sides of point faces when the points are open"

[JTGS850GL]

Yep, Condensers are pretty much just electrolytic capacitors. Some are not very tolerant to having a reverse voltage applied. You could lift the condenser wire and see if that opens up the circuit when the points are open.

If that doesn't work then, as Posplayer said, circuit isolation is the key.

[dturcott]

Thanks. Will do condensor first thing tomorrow. I work pm shift.
Is there any importance to the backfire when I manually opened and closed the points?

[OldVet66]

No, you manually caused the coil to fire. It's quite common with the Dyna-s electronic ignition when you turn your key on and off. Results vary depending on fuel vapors in the cylinders. The first time I heard it I thought there was a short in the electrical system that cleared itself.

[dturcott]

I pulled condenser wires and points no longer shorted.
battery cables still showing a little resistance,
Condensers are failing on the meter tests.
Picking up new tuneup kit this week. Ll post results

[dturcott]

Thanks for all the help. Project was put on hold because I bought an 06 vtx. But the tune up kit solved my problem. On three cylinders. Had to change a olug cap too. Rubning great. Now I just need to decide which to keep? Gs850, vtx1300, or bandit 600? Gs has most comfortable and familiar riding position.

[78550GS]

You don't really need the bandit when you have the GS.

I vote you drop the bandit off at my house and I will "store" it for you.

[60ratrod]

i say keep all of them and have options. that's what i'm gonna do once the gs650g and my kz1000m1 are both up and running.