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I've installed a 5-volt regulator IC in the place of the old electro-mechanical regulator on my D300. I'm getting 5.5 volts on the regulator output feeding the gauges, but my gauges aren't reading correctly. For example, the oil pressure gauge doesn't seem to be working at all. Of course the voltage source for these gauges is now a constant 5.5 volts rather than the old intermittent 12-volt supply. How much voltage should I apply to the gauges with a constant voltage supply in order for them to read correctly? Or am I analyzing the issue correctly? Would anybody please suggest how I should troubleshoot this? Thank you.
says to install a 270-ohm resistor in the circuit, but due to the poor copy I can't determine how the resistor is supposed to be connected.
The moparts.org page is unclear about whether you are supposed to install the resistor, but I am going to try installing it if somebody would please tell me where it goes in the circuit.
(Incidentally, I tried applying 9 volts as the constant voltage source for the 3 gauges. They did read somewhat more accurately with the 9-volt supply than they did with 5.5 volts, but the readings were still off quite a bit from where they should have been.)
Last edit: 1 year 4 months ago by hamjamming. Reason: correction
It turned out that my oil pressure sender was open, and since the three instruments (fuel, oil pressure and temperature) are supplied in parallel with voltage, if one of the senders is open you are going to get EMF back feed through that gauge. The weird readings I was getting on the oil pressure gauge from the back feed threw me off there for awhile.
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