come on now,, could it really be this simple?
what a joke:D:rollin:
I have a defective one in my white coug so with this good unit, I know what I have now.
so, in short,
Its a snap on circuit
-it has a spring loaded metal contact line points
-it has a screw adjustment to tune / calibrate it i guess
from the outside can to left snap connection = 60ohms
from the outside can to right snap connection = 60ohms
continuity from snap connector to snap connector.
Yup. I think it dates back to 1971 or so. I'm puzzled as to how it actually works.
i remember asking vinnie to snag one a while back so he or i could tinker with whats inside. It took me 10 min to carefully open the can.
its probably something similair to a shunt i would guess.
its probably a 50mA shunt since the resistivity of it is close to that.
when the IVR dies, you loose fuel and temp activity,,,,,i think. yeah i think im right on that. (for the simple clusters that have the temp / gas needle and lights for amps and oil).
I dont really care now how it works, I wanted to know how to fix the one that i have that is broke.
Im sure the theory of operation is in the shop manual somewhere by means of one of the troubleshooting procedures.
Hmm. Interesting article. I wonder if this explains why my fuel gauge doesn't like being at the halfway mark: when I go below around 3/4 tank the gauge drops to about 3/8 and stays there for a long time.
http://www.turbocoupe.org/techinfo/ivr/improved_design_solid_state_IVR.htm
Same way your turn signals work (or used to if you replaced the flasher module). Bi-metal strip in the contacts heats up, contacts open. Cools off, contacts close. It just does it at a much higher frequency, and the pulsing is averaged out by the mechanics of the gauges that it provides power for and that winding that looks like a coil. The choke (what looks like a relay coil from what I can make of the photo) would be to filter the noise spikes off the switching. More than likely, it's in series, down-stream toward the reduced voltage loads, i.e. OP gauge, Temp gauge, etc, etc. IIRC, it supposed to average about 5 volts by pulsing the 12V through that choke. This is why you ALWAYS get really weird readings when you try to check the voltage at the temperature sending unit or OP sending unit (if you have a gauge or otherwise) If you have just a switch on the OP, ever notice how dim the OP light is? Same goes for temperature if there's no gauge for that. If you put your meter on AC, you will get a reading on the output of that thing. I even checked the frequency of the signal one time, but don't remember what it was. Suffice it to say, though, if the frequency varies, the output of that thing is going to vary. As it gets older and fatigues, a tiny crack in the strip is going to make it operate VERY differently.
Now for the fun part. If you want to replace it with something MUCH better, and adjustable for accuracy, go get an LM-317 three terminal regulator, a small hobby board, and a hand full of other small components from Radio Shack, and build a REAL voltage regulator for your IP. Total cost will probably be less than $10.Then, you can calibrate the output using a decade box to simulate the OP, and Coolant Temp senders, and set it so that full scale on the OP and Temp gauges mean EXACTLY what you want them to. The gauges will be much more linear with the sending devices. Other than those gauges, that output isn't used for anything really meaningful. The car will run just fine without it, actually. You just won't have operable OP and Temp gauges. On some cars, not sure which year it changed, the fuel gauge also used that reduced voltage. On my truck, though, a '92, the only things on it are the OP and Temp gauge. The fuel gauge on the truck uses the full 12V to the sender. Don't remember about the two Birds, though. This is also a great way to build a much better panel dimmer than the gigantic power mongering rheostat on the back of your head-light switch.
BTW, IVR stands for Instrument Voltage Regulator. It isn't very integrated if it's hanging off the back of the cluster.
Ahh, with a closer look at my BRAND NEW 1986 EVTM, yes, it does indeed show up in there. In reality, its't NOTHING more than a normally closed relay that energized it's own coil. That said, the coil also serves to remove the spikes from the switching as i described above. (dI/dt)
The fuel gauge and Temp gauges are the only things fed by that thing, unless you have a Low Fuel indicator as well. That appears to be little more than a voltage sensitve relay that is looking at the drop across the fuel level sending unit.
If it starts operating more slowly, your temp gauge and fuel gauge will both probably read high, or you may actually see some pulsing of the gauges. They're dampened, so not sure how much it would take to see the pulses.
The EVTM doesn't indicate what the output should be, but it is definitely a normally closed relay, nothing more. Nothing magic about it. Looks like the case is grounded, one terminal the 12V in, and the other the 12V out. Male terminal appears to be output.
Oh yeah, included in that circuit is a resistive wire that should be 8.5 +/- .5 Ohms. Comes off the A1 terminal of the ignition switch, so my guess is it's going to be in the column somewhere. That would be the Black/Lt Green going through pin 12 of C285, circuit 687.
For lack of a better term, all our cars have built in vibrators. No wonder some of 'em get excited.
Gimme a minute, and I'll scan the page(s). On the Turbo Coupe, the TEMP, OP, and FUEL gauges are all fed by that little critter.
Here we go....
(http://i269.photobucket.com/albums/jj72/Old_Paint/1986%20T-Bird%20EVTM/1986TBirdEVTM116.jpg)
(http://i269.photobucket.com/albums/jj72/Old_Paint/1986%20T-Bird%20EVTM/1986TBirdEVTM117.jpg)
That should clear things up a bit. The symbol shown in that regulator looks more like a heating element than a relay coil, but that's just 30 years of field engineering speaking. Ford had their own mindset for symbols.
But, you can see, that resistive wire between the keyswitch terminal A1 can affect the performance of the IVR, AND we all know how finicky the keyswiches can be in these cars. A1 is on the end of the switch assembly that tends to separate. That normally causes a high resistance on any contacts on that end.
I did these in greyscale for best resolution versus getting to see the grey as light blue.
nice chat on the topic.
yeah we all pretty much know it creates the cluster 5v, thats its purpose. No on had been inside one before so i thought i would find out.
how it works ,, seems pretty basic. gotta pay attention to the contacts you see there. its like points on a dizzy. underneath the contacts is a screw which can be turned as to adjust tention on the contacts.
I would expect this to be something of a fuse and a voltage regulator in one based on the AWG wire and the turns ratio around the metal. The pic show more turns that what there really is. there probably isnt more than say 20 or so turns on the what appears to be 30-36awg wire. that wire is soldered to the little copper foil off to the side. the copper foil bonds to the case when the unit is assembled and crimped shut.
the real purpose of the thread is to see whats inside.
Because that's exactly what it is. Something has to heat up the bi-metal strip. You'll see the same wire wrapped around the "actuator" strip holding the needles in the other gauges. Here's a fuel gauge I just took out of my Turbo cluster to illustrate...
.
masterblaster,,
whats resistivity readings you getting on your gauge?
Not saying these are complicated, I just wanted everyone to know it appears that the faulty part would be the little wire winding and could be repaired pretty easy.
another thing to note is the adjustment screw. On the first pic, the adjustment screw is in the little circle above the left connection.
in the next pic you can see the end of the screw keeping the contacts together.
It does reduce the voltage down and with approx 60ohms at approx 12vdc, that tells us a lot.
12.5 ohms. Of course, you can't make any simple conclusions with that, since a heater wire's resistance will change drastically once it gets hot.
Example 1:
14.5v (running) / 12.5ohms = 1.16amps = 16.82watts
I'm pretty sure my dash never got that toasty.
Example 2:
H4 headlight bulb: 14.5v / 0.2ohms = 72.5amps = 1051watts
Obviously, the headlights would suck up ALL the alternator's output if the filament's resistance didn't change *really* soon after power was applied.
The only way to properly test is with an in-line ammeter to measure the flow, and calculate back to get the ohms with the circuit in use.
But that's a completely separate circuit, that just happens to be in the same case as the contacts. The power supply to the gauges doesn't go through the coil, just the points. And the circuit isn't isolated from the rest of the car, so the heater coil won't affect the voltage any more than opening the glove box and having the little light bulb turn on.
i think i used too many pr0nouns, i was just asking you what the guage resistance was (just curiosity) which had nothing to do with the voltage regulator.
Hi guys,
I'm going to solve this problem too. All my small gages go wrong, so I think it will be this problem. I saw you decided to use LM317, but why are you using LM317 with harness to set the correct voltage? Did you ever heard about 7805? It's one chip three terminal 5V regulator which needs only two capacitors to work. It's much more precise than LM317 with tons of harness. I'm going to use it. If the gages will need more current (I don't think so) I should use 78S05.
PS: Can someone tell me resistences of the oil pressure sender, pls?
PS2: I've read that article posted by Quietleaf. Jeff advise to use an LM338T, but it has one small problem - output voltage on the heat sink. The 7805 doesn't have it, the heat sink is connected to ground, so I can attach 7805 everywhere I want, for exmple on some bigger piece of metal under the dash and don't use the heat sink at all. 7805's operating temperature is up to 130°C, so I'm not worry about overheating problems.
Using the 7805 requires one thing. That you need 5 volts, and ONLY 5 volts. It is internally regulated and cannot be changed, i.e. will not allow you to calibrate the supply voltage to the sensors. The LM317, on the other hand, will allow you to calibrate the gauges by calibrating the supply voltage to the sensors (Coolant Temp and Fuel Level). There's plenty room to mount one, and it can even be done inside a plastic box and mount the snap fittings on it just like the original device. Chances are, the sensors for both fuel and temperature are fairly accurate, and a d'Arsenval meter (gauge) has been around for eons, and is also a fairly accurate device, especially when dampened as much as these are. What gets inaccurate, more often than not, is the IVR. The same type device is used in a VW, for reduced voltage to the fuel level sender, and on a VW, it is called a vibrator. (perhaps because that's exactly what it is) The Germans were not ones to call something a word that it isn't. There is no regulator to that device at all. It is simply a vibrator, that reduces voltage by lowering duty cycle. The instruments (gauges) filter off the pulses. With a solid state regulator, I'm just curious if there's better response from the instruments since the signal isn't pulsed.
i would venture to say the small winding in there could be observed as a possible shunt resource. should power this up and see what i get.
problem is i dont know what my baseline milivolt would be although i would know the mv drop, nor what ampacity the possible shunt would be.
i have often wanted to fab up a shunt for our cars, its such a simple concept, i deal with them all the time.
im not saying its a shunt,, just its possible it might be one by default.
The oil pres sender is one item i dont have documented in my diy,,, may take time tomorrow to get that for you. Since i have a full digi cluster, the oil data is coming from there so now i have to figure out where its at.
manual 33 05 35 test point TS3 says the resistivity of the "sender" should maintain a resistive value between 9 and 40 ohms while reving the motor a little back and forth.
I was actually interested in finding out what primary piece part manages the oil bar graph and did not find my answer. Apparently the sender does.
I found no hint of a sensor though.
Do you think the bar graph in full digital dash? I think it should work like an electronic EVmeter - it reads voltage on some resistor and compares it with values for low and high pressure, so the pressure sender could be same as for buttstuffog dash.
is that a question?
I was just commenting on the full digital cluster.
The other options on our cars is a single oil light. In this case, the oil sending unit is just an "on" or "off" switch and nothing more.
Sorry, my mistake. Edited.
Yes, I know about all 3 options. If the change of IVR won't take effect I'm going to make half digital dash by myself with microprocessor and small LCD.
So, I was yesterday in the garrage and was trying to measure resistances of senders. Unfortunately, I couldn't start the engine, because I have the battery in another car, so I have some numbers from staying car.
oil pressure sender ... > 200 Ohms*
temperature sender ... > 200 Ohms*
fuel amount sender ... 36,5 Ohms
*out of 200 Ohm range - I didn't remember the exact positions of each sender contact and didn't try higher ranges, because there were a lot of lower numbers
I think, that there must be some fault, because resistances over 100 ohms are out of ranges. Or not?
Here are all numbers I measured. Dash means resistance over 200 Ohms.
-....-....12,4...3,6...3,6...36,5.....-......-.......4,9
-...8,8...2,6.....3......3.....3,5....5,3...2,6....197,8
And finaly, I decided to open the IVR. It didn't do anything until I loosened the small screw. It didn't have enough force to bend the bimetal, so the contacts were still connected. Here are some photos:
(http://trinom.org/stazene/Ford/sIMG_0118.JPG)
(http://trinom.org/stazene/Ford/sIMG_0119.JPG)
I've finaly made the electronic IVR. This is the testing version. 78S05 is enclosed into the original IVR body. Here is a photo :)
(http://trinom.org/stazene/Ford/IVR/sIMG_0025.JPG)
very good pics man,, nice work on the replacement parts.
whatcha got there for parts?
I'm not definately sure if you're asking for the price or components, so I'll write both.
78S05 (5V stabilizer, up to 2A)
two capacitors (10 uF and 100 nF)
couple of wires, some bolt and two nuts
So complete repair cost me 15 Czech Crowns (it's little bit less than one dollar) :)
is this the correct wiring diagram?
If + means input and - output, then yes :)
Here is the wiring diagram:
Hey Gang,
I havn't gotten around to my V6-V8 swap yet,still building the engine and tranny ect.
My digital dash V6,87 Bird has a temp guage that's inop,no check engine light but car seems to run rough and rich,made me think it may be the temp sensor? Well I tried a new one along w/a tested T-stat and still nothing.
Any ideas? I'm not an electronics guru. Have the basic understandings but any ideas are welcome.
Hey Guys Just for an update.
This is sold on ebay for 20 dollars and it comes with no hassle warranty.
item number 270595341050
(http://[IMG]http://i31.photobucket.com/albums/c370/ivancaicedo/DSCF9048.jpg)[/IMG]
(http://[IMG]http://i31.photobucket.com/albums/c370/ivancaicedo/DSCF9019.jpg)[/IMG]
Yup, I saw that too and ordered one.