Help troubleshooting turn signal flasher unit

89 245. 130k, dealer maintained and very clean (including all grounds and fuses I have checked). The flasher unit began ticking erraticaly
without firing any lights a week ago. It quickly progressed to an even speed of about double it's normal blinker rate. I have replaced the flasher, most bulbs on the car and cleaned up a bunch of grounds and fuses, (even though none of them seemed to need any cleaning) and the flasher has gone back to erratic misfiring. I want to approach this more scientifically. I picked up a "Bentley" service manual and have been studying the wiring diagram. What I can't seem to figure from the wiring diagram is what voltages shoud be present at what points in the circuit.
What is the cheapest electrical test meter that I can get to be able to hunt down this problem?
More im importantly what should I test for at the flasher? There are three connections labeled "31", 49a", and "49" on the wiring diagram and on my flasher. "31" seems to be a ground. The other two I am not sure what I should be lookin for there. I want to know what reading I should get at each of these three connections when the hazards and blinkers are not engaged. Then I may be able to follow the source of the error on down the line. I assume that a voltage is being applied to the flasher when there should be none causing it to fire.
Am I correct in thinking if there was a short to ground somewhere fuses would be burning out or something worse?
In addition, the bulb out warning light has been acticg up and sometimes the rear window defroster is triggered by pressing the brake.
Please help because I love this car and really want to iron these things out.
Danny
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Danny
Terminal 30 on the flasher unit, is 0 volts (ground), terminal 15 is fed battery voltage via the hazard light switch, from fuse 13 when the switch is released, and fuse 9 when the switch is on, terminal 49a of the flasher is what goes to the bulbs, the flasher starts when it senses that there is a return path to ground through a bulb, (do not directly ground 49a, you'll fry the relay), and obviously 49a then goes live (battery voltage), switches off, goes live, switches off, ...... The indicator bulbs are connected to terminal 49a via the indicator switch. The seatbelt warning lamps are usually driven by the same relay, but the bulbs are controlled by switches in the seats and belt receptacles. Before you start ripping stuff apart and probing around with a multimeter, try changing/testing/servicing the hazard light switch, a bad connection here would provide a bad power supply to the flasher relay, possibly causing false firing, also spin the above mentioned fuses in their receptacles to clean the contact surfaces.
The bulb warning lamp issue has been well addressed by other posters, but can be caused by using mismatched bulbs, or possibly in your case the fact that as you mention, the defogger lamp activating with the brake; other posters and I have to agree, have suggested checking the wiring loom where it crosses through the tailgate hinge from the body to the tailgate, this is a bad failure point, wires bend, break, insulation fails, wires touch, check it to eliminate it, otherwise you'll keep being referred back to it.
Good luck, Ken
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Thanks a million Ken
I have checked ALL the things suggested in other posts. I have checked cleaned and spun all fuses and their seats. I have checked the wiring as it passes into the tailgate and it seems immaculate. I have replaced bulbs in pairs , cleaned receptacles and cleaned ground connections.
From my understanding of your answer, the flasher is always being fed live voltage, and it clicks only when it senses a path to ground through a bulb. Since all bulbs, including seat belt warning, are working, and none of them light in accordance with the flasher "ghost" clicking, it seems that there must be a leak to ground. But you say that grounding terminal 49a will fry the flasher so I am still mystified. I have replaced the flasher itself to no avail. Is there any way of testing the hazard switch or should I just replace it? I don't think it is faulty, I think it's a sneaky little glith in the wiring but I don't know how to scientifically discover it?
Danny

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With the ignition on, the flasher relay is fed a positive supply from the hazard light sw, with the ignition off, the relay is only fed a supply when the hazard light switch is activated, since you've changed the flasher, that should have eliminated it being faulty, if you don't get a flashing seat belt warning at the same same time as the 'ghost' clicks then it sort of eliminates the seat belt warning system, directly earthing 49a probably wouldn't fry the relay but it would blow a fuse. You can eliminate (or prove) the hazard switch by temporarily bridging the white and green wire attached to terminal 30 of the hazard sw to the white wire attached to terminal 49 of the hazard sw, use those clip on wire connectors, this will by-pass the switch, the hazard lights will still work, as will the flashers, but the extraneous ticking may just stop, do not leave this 'bridge' permanently attached, a study of your wiring diagram should show you that the flasher relay now has a permanent supply from fuse 9, it won't cause any harm, but, it's not how it's meant to be. I'm still worried about your mention of the rear screen demister switch illuminating when you press the brake, this indicates a definite leak of supply from the brake lamp wires into the demister supply wires, there is NO other way that the lamp could otherwise illuminate in this scenario, and unless the wiring has been tampered with, the loom going to the tailgate is suspect, no matter how immaculate it looks.
Hope this helps and isn't too complex,
Ken

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Ken, thanks again for your attention. I replaced the hazard switch yesterday with no improvement, although over the last few days the 'ghost' clicks have become less frequent. I am enjoying sorting this out and it seems to me, based on my deepening understanding of how this system works that there must be an intermittent, high resistance, leak to ground between the output of the flasher unit terminal 49a and ground. Does that sound right? If so, maybe the best course of action is to disconnect sections of wiring and replace with new wiring from that point (terminal 49a) forward until I have removed and replaced the leaky bit. What do you think?
As to the rear demister, everything looks immaculate at the hinges but I will begin to dig deeper. Otherwise, things are not so immaculate back there. The original owner had trailer lights installed and I can see it is incorrect (wired so as to guarantee bulb failure warning circuit will fire) and sloppy. I have disconnected it for the time being and will rewire properly in the future. Furthermore, my Bentleys manual, owners manual, and fuse panel cover all agree that the left and right parking lifgts are to be fed off two different fuses (15 & 16). Mine is not only fed off one fuse, but fed through a single connector to the fuse panel. What I mean is that I cannot simply take the tang that supplies the left side and move it to the other fuse because that single tang with two white wires, feeds bothe the left and right side parking lights.
Thanks again for your help, when this all gets sorted out I will actually think of you everytime I flick on the blinkers and they turn off in silence!!!!!
Danny

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Check the tailgate harness where they go through the hinges for broken wires also check the hinges for a broken ground wire some hinges have a ground wire but my guess is the tailgate harness going through the hinges Glenn
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