It doesn't say the IVR puts out an average of 5 Volts. It says the effect is the same as steady 5 Volts. Good info for testing the gage but not directly usefuli for verifying the IVR. When I tested the IVR in the '67 rally cluster you can see the voltmeter needle swings practicaly to full scale (8 Volts). Its not a true square wave or perfectly consistant in frequency. (link to video below) [URL]https://www.forabodiesonly.com...ltage-5v-or-6v-nominal.514919/post-1973864067[/URL]
Scroll through that thread ^^^^^^
You'll see several ways the gage and sending units can be checked.
Begin with a simple check of resistance in the gage and the sending units
Then you can input a 3 to 6 votls of dry cell power
and/or hook up some resistors or a potentiameter to simulate the range of resistances for the sender and input battery power through the IVR.
pdf version of the Master Tech Conference posted at MyMopar.com
Thank you for taking the time to reply and for posting those links.
Unfortunately I am not electrically minded and I thought that the oil pressure gauge, being on a seperate board, may not have been 5v.
I still can't see how the 5v power gets from the fuel gauge to the other board _ what am I missing there please?
Yes I have a Plymouth shop manual thanks, and I studied the wiring diagrams, tryting to nut it out.
I am wondering now if my Voltage limiter may in fact be working.
Because we did get that flash, pause, flash, pause on the circuit tester light.
I will look through those links that you kindly posted tomorrow, they may help me to understand.
Not to "muddy the waters" so to speak, but this car has an Aussie 318 in it. The Aussie Valiants used VDO gauges, and when I couldn't get a reading at first I thought that it may have been the senders on the Aussie engine being incompatable with the factory Barracuda gauges. that's why I bought new senders from Rockauto. Unfortunately the senders made no difference.