angus99
Guru
Apologies if this is too far into the weeds, but I’m replacing the older VDO tachs on our lower helm with new VDO SingleViu units and finding the directions less than complete for a shade-tree “electrician,” like me. Just want to confirm what I think is called for.
The tachs are reading Lehman SP135s and I’m using new Aetna 8902 signal generators mounted to the engines. I’m also using the analog signal option on the SingleVius to read tach pulses (for reasons that would just complicate this further).
The first photo below shows the five terminals connected to the existing tachs, where:
A is illumination power (the light comes on with a separate switch, not the ignition key)
B is illumination ground
C is tach signal
D is gauge ground
E is ignition power
The second pic is the instructions for the wiring harness. There are actually pigtails connected to the plug.
I think I need to do the following with the wires feeding the above gauge.
Connect wire A with Pin 6 (illumination)
Connect wire B with Pin 2 (battery minus/ground)
Connect wire C with Pin 5 (contact for analog tach signal)
Connect wire D with Pin 2 (battery minus/ground)
Connect wire E with Pin 1 (battery plus—which I assume is taking power through the ignition switch)
In addition there is a second wire coming off the signal generator that I assume connects to Pin 4 (ground reference for signal generator)
If all that makes sense, here is the issue I’m having: I would think that when I turn on the ignition key, I’d get 12.7 volts across wires D and E, but all I get is an OL reading. I also tried a circuit tester light and nothing happens. Does that voltage only appear when the engines are running? I can’t test that because the Lehmans are still laid up for winter weather, (which we got a nice does of last night).
Thanks in advance for any suggestions.
The tachs are reading Lehman SP135s and I’m using new Aetna 8902 signal generators mounted to the engines. I’m also using the analog signal option on the SingleVius to read tach pulses (for reasons that would just complicate this further).
The first photo below shows the five terminals connected to the existing tachs, where:
A is illumination power (the light comes on with a separate switch, not the ignition key)
B is illumination ground
C is tach signal
D is gauge ground
E is ignition power
The second pic is the instructions for the wiring harness. There are actually pigtails connected to the plug.
I think I need to do the following with the wires feeding the above gauge.
Connect wire A with Pin 6 (illumination)
Connect wire B with Pin 2 (battery minus/ground)
Connect wire C with Pin 5 (contact for analog tach signal)
Connect wire D with Pin 2 (battery minus/ground)
Connect wire E with Pin 1 (battery plus—which I assume is taking power through the ignition switch)
In addition there is a second wire coming off the signal generator that I assume connects to Pin 4 (ground reference for signal generator)
If all that makes sense, here is the issue I’m having: I would think that when I turn on the ignition key, I’d get 12.7 volts across wires D and E, but all I get is an OL reading. I also tried a circuit tester light and nothing happens. Does that voltage only appear when the engines are running? I can’t test that because the Lehmans are still laid up for winter weather, (which we got a nice does of last night).
Thanks in advance for any suggestions.
