74 duster my temp and fuel gauge were going to full so I purchased a new ivr, now the gauges don't move at all, so I put the old ivr in and the gauges go to full, so is the new ivr no good?
Thanks
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If both gauges read high, I would suspect both are shorted. Each one should have its own path to ground through its sending unit, but it sounds like both sending units are being bypassed.
All true. You cannot measure voltage output from old style IVR, It is off most of the time, And IMO not very reliable. that is why I built the new regulator. Seems to work well.Actually no, the IVR does not put out 5v. It puts out a pulsed 12V that is 12v for about 17-18% of the time and 0 volts for the rest of the time. It causes the thermal power in a resistive gauge circuits to be the same that a steady 5v source would cause..... and since these are thermal gauges, that is what counts. A circuit like Tim references will generate a steady 5 volts. The RTE limiter actually simulates the old style IVR, with a pulsed 12v output.
I measured my (original) limiter with a device that records voltage to a laptop and I'm getting 6.2 volts about 25% of the time, otherwise zero. That gives me an equivalent voltage of 3V (square root of 0.25 x 6.2 squared). Not surprisingly, my gauges read low. I was thinking I might fix it just by bending the bimetallic strip to make it stay on more of the time, but if it's supposed to be passing 12V there must be some excess resistance somewhere.
Mmmmmm..... I would not necessarily trust a computer recording device unless I had tested it on some rapid waveforms before and knew its accuracy. I have used an oscilloscope like Skykeith to see the pulses. If your IVR is really putting out a low voltage of around 6 volts, then the contacts may be be burned inside. Not sure if a contact file would clean it up or not. If it did, I bet some silver plating powder would fix it up..... or just get another one!
I have a new OEM style I can send you for postage.
Yeah... that computer hook up stuff is rarely lab grade equipment.... the software guys who know how to make it work with a USB computer interface rarely know much about actual hardware and the laws of physics. You ought to see the chaos that results when a mobile wireless link is added in....."What, the message didn't get through and I have to resend it? What do you mean about 'message acknowledgement?" LOLOh dang. I used a voltage sensor that is designed for school physics labs. I set it to 200 samples/second, so I thought it was good. But now that you mention it, I looked up the specs and it only measures up to 6 volts! So of course my reading tops out at 6. D'oh! Clearly I have some more troubleshooting to do.