I'm trying to resolve an issue with my temp/pressure buzzer alarm on a 1978 Catalina 30 A4.
After some hours of amateur sleuthing I still have no resolution, but may have enough clues for someone far smarter than I to give me a clue. Admittedly, electrical troubleshooting is not my strong suit.
The alarm unit behind the instrument panel is new and confirmed to work both when direct connect to battery and also when connected to its wires behind the panel in the troubleshooting test configuration described below. The oil pressure sending unit appears to work fine. Oil pressure increases after engine start and grounding the unit with key in the ignition position pegs the gauge to the right.
I believe the temp sensor and gauge also work although I don't specifically remember anymore whether grounding directly to battery pegged the gauge to right or not. But I confirmed that both senders have good ground to the engine. (side questions...why would grounding a sender unit directly to the battery negative post be any different than the unit getting its ground from the engine itself? Is the elec connector tip insulated from the body of the sender unit?)
The only test condition under which I have been able to get the buzzer to alarm when installed behind the panel is when the temp sender is grounded directly to the battery and key in ignition position or engine started, but in this configuration the buzzer remains on, regardless of oil pressure or water temp (although I didn't run the engine long enough to significantly increase the temp). I'm hoping that this last test result provides the clue to resolution, but if so, it has escaped me so far. Would that simply be an indication that the temp sender is bad? I'm trying to avoid random swapping of parts.
Much appreciation for any guidance on this.
Thanks
Eric
After some hours of amateur sleuthing I still have no resolution, but may have enough clues for someone far smarter than I to give me a clue. Admittedly, electrical troubleshooting is not my strong suit.
The alarm unit behind the instrument panel is new and confirmed to work both when direct connect to battery and also when connected to its wires behind the panel in the troubleshooting test configuration described below. The oil pressure sending unit appears to work fine. Oil pressure increases after engine start and grounding the unit with key in the ignition position pegs the gauge to the right.
I believe the temp sensor and gauge also work although I don't specifically remember anymore whether grounding directly to battery pegged the gauge to right or not. But I confirmed that both senders have good ground to the engine. (side questions...why would grounding a sender unit directly to the battery negative post be any different than the unit getting its ground from the engine itself? Is the elec connector tip insulated from the body of the sender unit?)
The only test condition under which I have been able to get the buzzer to alarm when installed behind the panel is when the temp sender is grounded directly to the battery and key in ignition position or engine started, but in this configuration the buzzer remains on, regardless of oil pressure or water temp (although I didn't run the engine long enough to significantly increase the temp). I'm hoping that this last test result provides the clue to resolution, but if so, it has escaped me so far. Would that simply be an indication that the temp sender is bad? I'm trying to avoid random swapping of parts.
Much appreciation for any guidance on this.
Thanks
Eric
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