64 Valiant IVR test

How can I test the IVR is working properly in my dash?
I believe it is located inside the fuel gauge. I'd like to check it while the car is apart for paint.

Easy remove the temp sender connector from the intake and measure between the connector and chassis ground. You should be reading about 5Vdc with your DVM.

66jim said:

Easy remove the temp sender connector from the intake and measure between the connector and chassis ground. You should be reading about 5Vdc with your DVM.

Click to expand...

Thanks, I'll plug it in and check that way before I go any further with the paint project. Just trying to address items as I access them.

BobW. You'll need an analog meter or a scope.
Video in this post: Fried gauges?

and this thread coveres a lot. Has links to Chrysler Master Tech in two different formats.
Test IVR

I haven't done any test yet this morning, but I suspect it may be partially working. I just wondered if a lower IVR output my be causing these issues.
My concern comes from the fuel gauge being non-linear as well as a perceived low and non-linear reading on the temp gauge.
Fuel reads full when tank is filled, but drops quickly to ~1/4 tank in about 125 miles, took ~7 gallons to refill. It does read empty accurately!
Temp runs just at the bottom of the "operating range" and is 180* verified with a temp gun at the thermostat housing and by putting the temp sender in a pot of H2O being heated on a camp stove.
The pic shows the needle positions my wife marked, from left to right, 100*, 150* 180*-thicker mark, 212*.
Again it seems non-linear in comparision to the scale.

I wouldn't fool with the old thermo-mechanical IVR inside the fuel gage. I slipped heat shrink over the arm to disable it. Rather than the $30 ones on ebay (search "voltage limiter") or $60 one from RTE, last pass I bought a generic 5 V adjustable supply on Amazon for ~$10. Surprise, it looked just like the $30 ones. By having an adjustable output, you can tweak it to make either your fuel gage or temperature gage read perfectly (not both). There are other adjustments on the gage needles, though intended for factory-only. To get my fuel gage to read perfectly on the full side, I had to add parallel resistors across the sender (maybe 20 ohm, forget) on the backside of the cluster, but depends on the sender (mine was new from China). The main advantage of the RTE Vreg is that it gets the needles moving faster when you first power on (as the old one did), it that matters (not to me). Photo of my 1964 Valiant cluster (latest effort):

OK, I just did the temp sender wire check and as mentioned the voltage on my digital jumped up & down. I'm guessing the regulator/limiter is an all or nothing function.
I can live with knowing the temp sender works and what range it displays.
Next time my tank is empty I'll pull the sending unit and check it's range. It may be an aftermarket replacement unit, so I understand that can be suspect.
Thanks for the info.

If you want the gauges accurate, use a 6V regulator, not 5.

BobW said:

OK, I just did the temp sender wire check and as mentioned the voltage on my digital jumped up & down. I'm guessing the regulator/limiter is an all or nothing function.
I can live with knowing the temp sender works and what range it displays.
Next time my tank is empty I'll pull the sending unit and check it's range. It may be an aftermarket replacement unit, so I understand that can be suspect.
Thanks for the info.

Click to expand...

That jumping of the meter is probably the meter is unable to average out the mechanical aspects for the IVR. It is a 12V duty cycle output that 'averages' out to approx 5V, not a pure 5vdc. Try a different DVM or an older analog meter. I have had a few original IVR have a low duty cycle output causing the oil pressure, water temp and gas to read low.