telford dorr
Samba Member
Joined: March 11, 2009
Posts: 3556
Location: San Diego (Encinitas)
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 Posted: Thu Apr 09, 2020 11:05 pm Post subject: Re: 69 electrical hacks by PO, need advice |
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| asiab3 wrote: |
| Telford pretty much got it, I just didn't see this part addressed… Your indicator light function is normal |
Yeah, I kinda skipped over that, to avoid adding confusion to the main topic.
If one checks the schematics, one will see that the common side of the turn indicator lights is wired to switched 12 volts. This means that when the ignition switch is on, one has to ground the control wire to the indicators to make them light. This is the indicator requirement when in turn signal mode, key on. When the ignition switch is off, the common side of the turn indicator lights is effectively grounded thru all of the switched ignition circuitry (at a minimum. thru the carb choke heater and ignition coil, if the points are closed). This means that the control wire to the indicators has to have 12 volts on it to light the indicators. This the indicator requirement when in 4-way flasher mode, key off.)
So: to make the turn indicators work in both turn signal mode and 4-way flasher mode, the indicators have to be driven with a signal which swings to both 12 volts and ground, regardless of the ignition switch position. How do we do this? We must do one of two things:
1) use a flasher relay which has a Kbl terminal which switches between +12 volts and ground. The factory stock relay obviously does this. Other relays may not...
2) connect the indicator wire which normally goes to the relay Kbl terminal to terminal 49a (the flasher output) instead. When the flasher relay is driving the turn lamps, 49a is at 12 volts. when it's not, it is at ground (e.g. the indicator lamps ground thru the unlit turn lamps.) Side effect: this means the indicators will flash with the turn lamps in 4-way flasher mode (ignition off) and opposite of the turn lamps in turn signal mode (ignition on), but who cares?
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'71 panel, now with FI
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