Dakota Digital with 2 fuel tanks help. (2 Viewers)

[Mightymes]

Has anyone hooked up a Dakota Digital cluster with 2 fuel tanks. I'm trying to do it with a DPDT switch, but I keep getting a EEE fuel error on the display. I've followed Downey's general directions on how to wire it up and the plumbing, but it seems like I'm missing a step here or there???

 

[charliemeyer007]

Are the sender units for each tank operating in the same range? Back in the 80's I put an auxiliary tank from a Datsun B210 12.5 gallon, behind the axle. By carefully adding small value 2% resistors to the wire from the Datsun, I was able to get my dash gas gauge to read from E which was empty to 1/2 which was actually full. I could flick the switch to read either tank.

 

[sogncab]

I'd call Dakota Digital

 

[Living in the Past]

Should only need a single pole double throw. Cut the wire going to the main sensor and attach it to the center post on the switch. Then attach the wire coming out each tank sensor to the two other poles on the switch. Other side of the sending the tank is ground. I would just leave the wire going to the screw on the sending unit alone.

 

[TreadingLight]

Why not use a dpdt switch?

The Dakota wants two connections for the fuel sender - the ground and the signal wire. If you switch both I would expect you'd get a more consistent reading than having only one of the senders' grounds tied to the Dakota.

And definitely make sure you have two senders with similar resistance/range as mentioned above.

 

[Mark Jennings]

The Dakota Digital allows only one calibration, based on resistance from the sender. You could use a SPDT switch, but if the senders differ in resistance, you’ll get a bum reading from the second tank.

In my rig, we only use a sender in the front tank, run the back tank dry or simply track milage, then switch to the front tank.

 

[Living in the Past]

Why not use a dpdt switch?

The Dakota wants two connections for the fuel sender - the ground and the signal wire. If you switch both I would expect you'd get a more consistent reading than having only one of the senders' grounds tied to the Dakota.

And definitely make sure you have two senders with similar resistance/range as mentioned above.

Single post switch has half the parts to fail. Running a wire between sending units ground wouldn't be a bad idea. Electricity always takes the path of least resistance. So that means the ground at each tank is what will seen at the Dakota. Dakota will always have two wires. After landing a wire between the tank sending units not a bad idea of putting varnish on all the wire connectors. I live in AZ and never had an issue. Other parts of the country it a bigger issue. As for accurate Toyota sending units always read empty long before the tank is actually empty.

 

[TreadingLight]

I think the important thing is that the Dakota sees a similar ground and that it gets a similar signal (range of resistance) from both senders.

I imagine either approach (a dpdt switch or linking the ground ground wire in series from the Dakota to each of the two senders) would work but I don't see a dpdt switch as being sufficiently more complex as to be more likely to fail.

This may be hair splitting given that we are just talking about a fuel level sending unit but this is not quite accurate:

Electricity always takes the path of least resistance.

It will take multiple paths if they exist, proportional to the level of resistance in each path.

 

[Living in the Past]

The Dakota may be high tech but it still excepting an old school sending's input. An EEEE code could just be an wiring error if your getting an EEEE on both tanks.

 

[Mightymes]

I played around with it today and figured it out. I do have both sending units with the same ohms and they are both grounded together with the ground going to the DD brain as I call it. What I've found is that the switch must be in either on position when you turn the key. If not, the DD is not getting a signal so an error code appears. I can't simply switch them on the fly without turning the truck off, but I'm ok with that. Everything else is working as it should.

 

[charliemeyer007]

I think that is a good solution you can easily work with. Most of the time the odometer is a better estimate of fuel range IMHO. Tank size and gallons per hour type of reckoning.

 

[Mark Jennings]

I played around with it today and figured it out. I do have both sending units with the same ohms and they are both grounded together with the ground going to the DD brain as I call it. What I've found is that the switch must be in either on position when you turn the key. If not, the DD is not getting a signal so an error code appears. I can't simply switch them on the fly without turning the truck off, but I'm ok with that. Everything else is working as it should.

Well that’s pretty interesting, must be the DD ‘brain’ goes through some sort of self check when you first hit the ignition…..some problems with my DD fuel indication….1st half tank seems to last forever, then drops rapidly on the second half. Oil pressure sometimes pegs high with the simple fix of pull the sender plug, pinch the terminals tighter and a bit of silicone on the rubber seal. And the oddest one is the speedo cable slipping out of the brass key every now and then. Other than that…I really like the unit, brings a taste of modernization to the 55 YO girl.

 

[Living in the Past]

Do you have a two position switch or three position switch where the middle position does not complete either pole?

 

[Mightymes]

Well that’s pretty interesting, must be the DD ‘brain’ goes through some sort of self check when you first hit the ignition…..some problems with my DD fuel indication….1st half tank seems to last forever, then drops rapidly on the second half. Oil pressure sometimes pegs high with the simple fix of pull the sender plug, pinch the terminals tighter and a bit of silicone on the rubber seal. And the oddest one is the speedo cable slipping out of the brass key every now and then. Other than that…I really like the unit, brings a taste of modernization to the 55 YO girl.

It does make sense to me to have the switch in the on position otherwise it's not getting any signal at all. This is my 5th cruiser with a DD and I've had pretty good luck with them thus far.

 

[Mightymes]

Do you have a two position switch or three position switch where the middle position does not complete either pole?

It's a DPDT. Yes, the center position is off so nothing happens.