9406 Gunpowder Rd., Florence, KY 41042
Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS
Wrong flasher can run battery down
Posted by: BlownMGB-V8
Date: March 04, 2018 07:25PM
My MGB with AA wiring uses a 3 post flasher unit for both the turn signals and the hazard. I had an issue with the battery draining over time and eventually tracked it down to the flasher unit. There are now a bunch of 3 post flashers available. I was using one that had "35" in the number and had a 36 in the turn signal circuit. The hazard circuit showed a 200 ohm resistance when switched off and with the fuse pulled. That's a continuous 65ma drain and will ded the battery over a week or so of unuse. Switching the flasher to the 36 fixed it.
I may have got the numbers backwards. If you have this problem just pull the fuse and check for voltage across it. If there is, you can check resistance on the load side to ground, it should be infinite.