How to test RTE IVR4 voltage limiter?

[Dino]

I think mine is dead...

I'm using a 12v output on the middle of the three tabs on the limiter.  The old limiter I have and the one that made my gauges peg is giving me an output of 5.2 volts on the peak of the ac cycle.  The IVR4 at first had the LED on as soon as I gave it 12v (it's supposed to be good from 9v - 18v) and gave an output of 2.8v but now the led is out and as soon as I hit the 12v power lead to the central tab, the voltage drops to zero.  What the heck??  Did I fry this thing somehow?


EDIT:  It turned out to be the power supply itself.  I tried another and the limiter's LED is blinking again and output is 5v.   

[Just 6T9 CHGR]

Good to know because Im about to purchase one myself

[Dino]

Little update on this, as you are about to order one...the output on the IVR4 is now 0.5v and the LED is out.  I have no clue what's going on.  It worked flawlessly since I bought it 2 years ago.  I emailed RTE a few minutes ago, will keep you posted.

[Just 6T9 CHGR]

Crikies! 

[PlainfieldCharger]

I have one in my dash. Working well after about 1500 miles.

[Pete in NH]

Hi Dino,

I'll be interested in what RTE has to say. My take on it is if they really duplicated the function of the old electromechanical regulator it would not be easy to measure the output voltage.

Lets see if I can explain how this thing works- The gauges in the car are thermal types and operate by the temperature of a bi-metal strip to move the pointer, the hotter the strip the more the pointer moves up scale. There is a coil of nichrome wire wrapped around the metal strip to do the heating. The gauge sending unit controls the amount of current through this heater. Okay, that's how the gauge works.

The voltage regulator has the job of reducing the 14 volt electrical system voltage down to 5 volts for the gauges and here is where things get a little tricky. If I turn on the voltage regulator on for 5/14 th's of the time I get the same heating effect in the gauges as a steady 5 volts. This is what the old mechanical regulator did, pulsed on and off to give the heating effect of 5 volts. I suspect RTE has done the same thing electronically. So if you try to measure the output of the RTE limiter with a voltmeter you may not see anything. I would try connecting a 20 ohm or so resistor between the RTE regulator and ground and see if it gets warm ,a 5 or 10 watt resistor is fine. I think the issue is the regulator needs to source current to something. It wants to heat something up as it would the gauges.

[resq302]

I've started having an issue last year with my coolant temp gauge and I had a spare lying around and sent it down to Performance Car Graphics to have tested.  When I told him what limiter I was using, David said that he has been getting a lot of people lately with issues with the RTE limiter not sending out the proper voltage.  Not enough to fry the gauges, but enough to cause them to read high or not at all.  I am curious, too, to see what the problem might be.  Maybe the RTE units do not hold up well.  I've had mine a few years now and this is the first issue.  My coolant gauge was reading high by about 30*.  Changed out the sending unit with an NOS one, no change.  Checked all of the wiring connections, all good and clean and no breaks or cuts in the wire.  Now that the gauge is rebuilt, I have to wait for a nice day to take the car out and double check the new gauge.  If the gauge still reads high, could be the RTE limiter.

[Dino]

I did have a spare stock limiter which I used to calibrate the last of the gauges and the output is variable because of what Pete said.  However my multimeter does read it fine and you can see it cycle to average around 5v.  I cannot however measure the exact output.  No big deal as I would be using the limiter I calibrated the gauges with.  The IVR4 worked great and I was able to calibrate two gauges.  When I hooked it up the next day to calibrate the third, it stopped working.  0.5v output, connected to a gauge or not, and no LED. 

So I sent an email to RTE and got a reply from Tom this morning.  He said it sounds like the polarity was reversed, ie I hooked it up wrong.  I don't 'think' I did so but at this point I am unsure of what happened.  I am sending the IRV4 back to RTE and they will repair or replace as needed. 

Maybe they do fail, but to be honest so do the stock ones and they WILL fry your gauges whereas when the IRV4 fails, the output goes to 0 and that saves the gauges at least.  That alone makes this an easy choice.  There is no way I'm using a stock limiter ever again.

When I get it back I will recalibrate the gauges and then I should be good to go. 

I used the Radio Shack resistors to calibrate the gauges.  I have 10 ohm for the high reading, 73.2 for low and 22.3 for middle.  Is the latter close enough?  The gauges read exactly high, low and middle with this setup and this is the first time they actually work as they should!      

[resq302]

Dino,

How did you make the set up to calibrate the gauges?  I'd love to try and calibrate mine when they are out of the car as I have spares of each gauge.  Hell, I pretty much have a spare cluster set up with switches and all with the exception of the speedometer and tic-toc-tach and the face plate for them.

[Dino]

Dino,

How did you make the set up to calibrate the gauges?  I'd love to try and calibrate mine when they are out of the car as I have spares of each gauge.  Hell, I pretty much have a spare cluster set up with switches and all with the exception of the speedometer and tic-toc-tach and the face plate for them.

You will need a few resistors or you can get a resistor substitution box.  I chose the separate resistors as I have no use for any other.  I went to Radio Shack and bought 271-1101 (10 ohm), 271-1103 (22 ohm) and 271-1109 (150 ohm).  They come in packs of 5 each.  I also bought a set of alligator clips with leads.  It was just under $13 total.   

Take 1 of the 10 ohm and one of the 22 ohm resistors.  Grab a multimeter to make sure they read correct.  Grab two of the 150 ohm resistors and tie them together on each end.  They should now be around 73 ohm combined.  Grab the other two resistors you already had and tie one end of each to one end of the tied 150 ohm resistors.  You now have 4 resistors tied together on one end.  Hook it to ground.  I use one of those little soldering stands with alligator clips which is my ground by running a lead from anywhere on the stand to the negative terminal of a car battery.  Grab the limiter and stick the ground tab in the other alligator clip of the stand. The middle tab is 12v input, the bottom tab is 5v output.  Run a lead from the positive battery terminal to to the limiter's middle tab. 

Run another lead from the bottom tab of the limiter to one post of a gauge, doesn't matter which one.  Run a lead from the other gauge post to one of the resistors. 

I suggest hooking up all but the alligator clip on the battery's negative terminal until you are sure everything's hooked up correctly.  I also have my multi meter hooked up to the 5v output so I can pull the ground in case it goes over 5v.

By having the resistors in the alligator clip, all you have to do is put the lead coming from the gauge on either one to see what needs to be tweaked.  Grab a small screwdriver to tweak the mechanism by moving the teeth visible through the small holes.  The upper most tweaks anything from mid to high, the lower calibrates low to mid.  Moving one affects the other but it is pretty easy to get them to read right with a few tries.

[resq302]

great work!      I'll have to copy that!

[Nacho-RT74]

lilwendal show us how to calibrate the gauges on his Cluster resto thread.

talking about test the cluster voltage limiter!! I guess you'll need an ANALOG tester, to show the RMS voltage coming out from limiter... Digital tester takes samples of voltages so they can catch or not some voltage impulse if it made to match the moment when the sampling happens.