Digital Dash

[Ivan141]

I really have no idea why (and indeed if) the digital gauge needs this fuel signal for the tach to work, but if it does the above schematic is not ideal.
On the analog fuel sender (which should be similar to the digital one except for its resistance range) fuel sender ground splits off into a thermistor for level warning, and a rheostat for level measurement.

Applying that logic to this schematic I would say it is better to have a wire coming from pin 12, splitting off into a resistor to pin 5 and a resistor to pin 13.
As for resistor values: The low level warning probably triggers when resistance goes higher (due to higher temperature when it looses cooling from the surrounding fuel), so 180 is probably a good value to use.

I found the following suggested range for the level sender:
Full = 270 Ohms
Empty = 17-33 Ohms,

If that's correct 120 ohms would put you right about half full.

SO... why doesnt this work for you? Here's a possible explanation (wouldnt be surprised if it turns out to be wrong):

I expect the cluster is putting out about 12V on both pins 13 and 5 with nothing connected. If you now put that 120 ohm resistor across 13 and 5 like in the drawing, pin 13 will still be seeing 12 volts, so basically it's almost as if you haven't connected anything to pin 13.

[choyr]

hi ivan, thanks for the explanation. this is the connection you are referring to? still connected to ground?
thanks

[Ivan141]

I think the ground connection might not be strictly necessary, the cluster probably provides it on pin 12 (otherwise: whats the use of that pin?). You could check this by measuring for continuity between pin 12 and the known ground pins of the cluster with a multimeter. Cant do much harm to leave it in though.

[choyr]

it's not working. anything else i have to check? thanks

[Ivan141]

Get some facts established first:

-What signal are you using? Coil-? I read you have a KE70 and also that you use a distributor, but it's important to know if you are using coil- or some other tach signal source. Does an analog dash work when presented with the same signal?

-What are the fuel level indication and warning light doing? If the circuit we where discussing is correct, I would expect the warning light to be off, and the level indication to point a little below half full.

[george delorean]

choyr Wrote:it's not working. anything else i have to check? thanks

Got error again involved in!
Pin 12 and 2 Ground
Pin 1 and 9 + 12V
Pin 13 Fuelsender
Pin 5 Fuelsender light (not ground)!!
Pin 11 Tach signal From Tyristor distributor!!!!!

Must involve more resistance for 126 ohm
122 + 4 ohm.

[Ivan141]

He's got it exactly connected like that now..
About the schematic you posted: I explained earlier what might be wrong with it..
As for 126 ohm: any value between 30 and 270 should do the trick.. the original fuel sender also varies in value, so why should 126 be any better than 120?

About pin 7: that hasn't been mentioned before.. Makes no more or less sense that it should be connected for the tach to work than the fact that the fuel sender should be connected, so it's worth a shot. Wish these things weren't so bloody expensive so I could afford one I could test all these odd issues myself..

[george delorean]

Ivan141 Wrote:He's got it exactly connected like that now..
About the schematic you posted: I explained earlier what might be wrong with it..
As for 126 ohm: any value between 30 and 270 should do the trick.. the original fuel sender also varies in value, so why should 126 be any better than 120?

About pin 7: that hasn't been mentioned before.. Makes no more or less sense that it should be connected for the tach to work than the fact that the fuel sender should be connected, so it's worth a shot. Wish these things weren't so bloody expensive so I could afford one I could test all these odd issues myself..

Since the exact values ​​I measured the original digital fuelsender,
should not be changed values.
Change the value could be triggered when the state will not work tachometer.

[choyr]

Ivan141 Wrote:Get some facts established first:

-What signal are you using? Coil-? I read you have a KE70 and also that you use a distributor, but it's important to know if you are using coil- or some other tach signal source. Does an analog dash work when presented with the same signal?

-What are the fuel level indication and warning light doing? If the circuit we where discussing is correct, I would expect the warning light to be off, and the level indication to point a little below half full.

hi ivan. the coil is -, it is working when connected to analog cluster (from KE70). this is the distributor used in blacktop.

fuel level indication is showing full indication, same as the temperature. but the connnection to temp is not connected.

I will try again today to check if there will be changes.

many thanks everyone

[choyr]

still not working.. argh, i don't know if the IC is still working or not