Friday, February 26, 2010

Troubleshooting an Electrical Short on the Ural

The battery was running down while connected to the Ural. It also wasn't charging on the tender when connected to the bike. I realized I might have a short, and needed to track it down.

1) Start with everything off. The key and the kill switch.

2) Disconnect the negative cable (black) on the battery.

3) Connect the voltmeter to the positive side of the battery and the negative cable removed in step 2. It should read 0.0V. If not, then there is an electrical draw in the system somewhere. It is likely a short since everything is off. Mine read 0.52V. 
phantom draw of 0.52V

4) Locate the fuses on the bike. On the Ural there are two blocks – one near the forks the other in the side car. 
sidecar fuse blocktug fuse block
Remove one fuse at a time looking for the voltage to drop to 0.0V. This will indicate which circuit is the problem.
no draw when corroded relay removed
After checking every fuse twice, I still had a draw. I started disconnecting other things to check them. Eventually, I removed one of the head light relays on the left side and it dropped to 0.0V. The relay looks a tiny bit corroded. It looks worse in the photo than real life.
problem relay - corroded
I cleaned it up and added some dielectric grease to keep out future moisture causing corrosion.
dielectric grease
I greased both relays and put them back in.
dielectric greased up headlight relays
The draw went to 0.06, so I pulled them out again and removed a bit of grease. I put too much on the first time. Then I was back to 0.0V.

The battery was at 6.78 and put back onto the charger for the night. By morning, it was back up to almost 13V. I rode to work and was down to 12.7. By the time I left work, it was still 12.7. I think the problem has been resolved.

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