Rallye Dash Gauges with aftermarket Wiring Harness

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KS Hcode

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Since I haven't found what I was looking for searching through posts, I thought I would ask here and see what I can gather.

I bought a Kwik Wire harness for my 71 H Code Duster. It has a Rallye Dash and I am concerned with wiring the dash up and frying the gauges. I did get a 12v to 6v reducer with the wiring harness but I am not sure that is enough. I have seen guys say the factory reducers cut the power down to 3 v.

If that is correct what can I do to ensure that I am not going to be looking at replacing instruments that are ridiculously hard to come by?

T I A for your help!
 
KS Hcode said:
I have seen guys say the factory reducers cut the power down to 3 v.
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that is NOT correct and I would not be taking wiring advice from anyone who is telling you that.

The stock IVR (Instrument Voltage Regulator) in a ralley gauge cluster is built into the Fuel gauge. The fuel gauge has 3 posts, one for 12V input, one for the sender and one to OUTPUT approximately 5-6 V for the Temp and Oil gauges

The stock IVR works like a blinker, it has a bimetal strip inside and a heating coil. As the heating coil gets hot it disconnects the output of the IVR so the output voltage goes to 0V. As the heating coil cools the contacts reconnect it sends 12V to the output. this happens at a frequency - on off on off - creating a square wave that averages about 5-6 volts. Because the gauges are electro mechanical they don't care that the voltage is turning on and off.

Chrysler Master Tech Video that explains it in detail.




As for the "Kwik Wire" harness, I assume it is not a stock replacement harness so you will have to defer to their "wisdom" as to how to hook it up.


TYPICALLY when the IVR fails in a ralley cluster an external IVR is added (BUT the internal IVR in the FUEL gauge MUST be disabled) RT-Eng makes a really good IVR and have instructions on how to disable the IVR in the Fuel Gauge

RTE limiter - rte
 
If you are talking about the voltage regulator for the gauges, 6 volts is a good voltage. I would wire up the dash on the bench to make sure you have everything right before you install it.

You can buy some resistor on Amazon to check the gauges. Tie one side of the resistor to ground a the other side to the sender wire. Don’t leave the gauges reading over full scal for more than a few seconds or they will burn up.

10 ohm - full scale
22 ohm - half scale
70 ohm - empty

These are approximate values that are close enough for what you are doing. Get 5-10 watt resistors.
 
Thank you for the quick reply and I appreciate the added wisdom! I will definitely keep all of that in the memory bank when the harness is getting laid in the car and components are being hooked up.

You are correct, it is not a factory replacement. I will definitely use their help to make sure that I get everything attached correctly.

Thanks again.
 
KS Hcode said:
You are correct, it is not a factory replacement. I will definitely use their help to make sure that I get everything attached correctly.
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Just my 2 cents... cut your losses! UNLESS you are a wiring guru get a factory replacement harness MOSTLY plug and play
 
Mike69cuda said:
If you are talking about the voltage regulator for the gauges, 6 volts is a good voltage. I would wire up the dash on the bench to make sure you have everything right before you install it.

You can buy some resistor on Amazon to check the gauges. Tie one side of the resistor to ground a the other side to the sender wire. Don’t leave the gauges reading over full scal for more than a few seconds or they will burn up.

10 ohm - full scale
22 ohm - half scale
70 ohm - empty

These are approximate values that are close enough for what you are doing. Get 5-10 watt resistors.
Click to expand...
No. The IVR is part of the cluster, not something else. Use either the OEM built in one if it works, or buy something like an RTE. There is a sort of "how to" on the RTE site on how to do that

RTE limiter - rte

www.rt-eng.com www.rt-eng.com

RTE Gauge Faq - rte

www.rt-eng.com www.rt-eng.com
 
Del, I assumed the “reducer” he was talking about is an IVR replacement? I wonder what he has if that is not what it is?

I also assumed, probably incorrectly, that he already had the factory IVR disabled.
 
The factory IVR is not disabled. I actually knew nothing about a y of this..

I am not sure what the unit is that came in the kit but I am hoping it is some sort of IVR unit.

After this convo I am going to hope that the factory fuel IVR is all good and roll that route! Thank you guys for the help!!!
 
KS Hcode said:
After this convo I am going to hope that the factory fuel IVR is all good and roll that route! Thank you guys for the help!!!
Click to expand...
I wouldnt "hope" that the old factory IVR is good and bet your gauges on it, the conversion to the one @Dana67Dart and @67Dart273 told you about is inexpensive and very very simple to do. Personally, I went the RTE route and had no problems doing the conversion.
 
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