Chevy Nova Forum banner

1 - 15 of 15 Posts

·
Premium Member
Joined
·
3,487 Posts
Discussion Starter #1
ok,
So I am pretty sure I have ruined my Speedway Interface Module- as there is no longer an led light displayed. Without getting in to all of that( I have removed it for now) here is what i have:

New GM 0-30 ohm sending unit ( from Chevy II Only)- I have proven it to be o.k.
Omega Custom gauges- The supplied sending unit reads 30- 254 range but does not fit my tank. having said this it would be safe to say that the gauge is set up for 30-254 ohm.

question- can I use a resister in line to "fool" my in dash gauge?
 

·
Registered
Joined
·
423 Posts
Can you get your hands on say....a 60 and a 250 Ohm resistor both? Using them in a test circuit like Custom Jim explains in an Electrical Section thread, started by Winch 3 months ago entitled "Fuel Gauge Woes" on pages 2 & 3 will determine if your gauge is in fact a 50-254 Ohm BUT.....since the manufacturer included the tank sender with the gauges, I'd say it probably is 50 -254 Ohms.
If you want to test it anyway, any and all values of resistors can be found at Monroe's in that foggy city near you. Ask for 10% Tolerance, 2 Watts (you only need low watt resistors). Use a lower value resistor first to ensure you don't overdrive the gauge (should show below Full). Adding additional resistors in series (string them end to end) will increase the overall resistive value and increase your gauge display up to Full - 250 Ohms.

question- can I use a resister in line to "fool" my in dash gauge?
Unfortunately, you can - yes, unfortunately, but you'd have to choose one extreme gauge display value - either empty or full. All other values would be essentially useless. To obtain a 'full' value, that would require a 230 Ohm resistor.

But for shitz n' grins let's say you did install an in-line fuse to "fool" your dash gauge. Which would be the best value?
Let's choose 50 Ohms. It will at least show you as empty when you're actually empty. Then filling the tank by pumping until she spills-over or clicks off would give you a value of 80 Ohms at the gauge which would mean you'd be too handy to empty all the time. You'd have to be 'Vewy, vewy carewful', as Elmer Fudd would say.
Simply NOT recommended, is what I would say.

Sorry acd65post! Unless someone here has a better idea, you're likely stuck with either a new gauge or sender.
 

·
Registered
Joined
·
4,649 Posts
Hi There .. . . . . . . just throwing this out . . . . . . .

I think this would solve u'r issue - look here :


also listed at Classic Instruments = part # SN 34 .

and here's my issue - I have the SN 34 that I want too hook - up = (not hooked
- at this time) .
(my dash gauge quit working several years ago) . . . so, I installed a (2 1/8" ) S/W gas gauge . It reads my fuel level . . . . .
but, is about a 1/4 reading off ( meaning : at empty (on my gauge) = I still have a 1/4 tank of gas . . . .
which is OK with me . But , everybody wants their gas gauge "to work & read correctly" (me too) .
That is why I bought the ' SN 34 ' ........................................ and some sending units , could cost close
to this unit ...........................
You should read - up on this unit , it's pretty neat and really works with any gauge & sender
"mis-match ohms" (and, I have watched a 'you-tube-vid' ) about how to set-up the SN 34 unit .

OR -

maybe this :


> > > 'Meter Match instructions' :

looks like the same idea . . . .

jim
 

·
Moderator
Joined
·
6,498 Posts
Yep, there is no simple way to just "add" a resistor.

There are a few different sender resistance value setups and I have to ask on yours is the 30 ohms for empty and the 254 for full or the other way around ?. The reason I'm asking is on a google search it shows

  • Ford up to 1986 - 73-10 Ohms
  • Ford 1987 & up - 16-158 Ohms
  • GM up to 1964 - 0-30 Ohms
  • GM 1965-1997 - 0-90 Ohms
  • GM 1998 & up - 40-250 Ohms
  • Mopar up to 1986 - 73-10 Ohms
  • AMC 1950-1977 - 73-10 Ohms
  • Autometer -240-33 Ohms is the most common however other ohm ranges are made
  • Classic Instruments - 240-33 Ohms (excluding vehicle specific gauge kits which use factory ohm range)
  • Dolphin - 0-90 Ohms
  • Dakota Digital - Programmable to work with most Ohm range senders
  • VDO - 10-180 Ohms
The first number represents the empty Ohm reading and the second number is the full reading.

Not to pry into your business but did you damage the Speedway interface module or did it just go south ?.

It looks to be a $105.00 or so part and maybe Speedway can direct you to the manufacturer and see if they offer some kind of repair service.

Jim
 

·
Premium Member
Joined
·
3,487 Posts
Discussion Starter #5
Jim- The sender in the tank is o empty and 30 full. The universal that came with the guages is probably the 40 empty - 250 full as you show ( will have to double check as now I am second guessing myself.
Normally the speedway module would have a red led lit- and it did when I installed it ( last year I think) but it was reading just under half and I ran out of gas when my Wife and I were out for a cruise( lukily it ran out just when I was backing it in to the garage:)). It was reading just under half at the time. I dug out the instructions and I started messing around with the potentiomter settings and next thing I new it stopped working all together no led light. I know the gauge is ok because when I removed the module and hooked the gauge back up it reads full.

I wonder if there is a way for me to change out the rheostats on the fuel sending units.
 

·
Moderator
Joined
·
6,498 Posts
Jim- The sender in the tank is o empty and 30 full. The universal that came with the gauges is probably the 40 empty - 250 full as you show ( will have to double check as now I am second guessing myself.
Normally the speedway module would have a red led lit- and it did when I installed it ( last year I think) but it was reading just under half and I ran out of gas when my Wife and I were out for a cruise( luckily it ran out just when I was backing it in to the garage:)). It was reading just under half at the time. I dug out the instructions and I started messing around with the potentiomter settings and next thing I new it stopped working all together no led light. I know the gauge is ok because when I removed the module and hooked the gauge back up it reads full.

I wonder if there is a way for me to change out the rheostats on the fuel sending units.
I had never really dug into what different resistance scales were used on different cars or from different manufacturers but when I saw that GM 1998 & up used 40-250 Ohms and then Autometer & Classic Instruments using 240-33 Ohm setups had me wondering what you have.
I do know you do not need to be super particular in your measurements/reading in that there will be tolerances on things. For example the 40-250 one for GM might read 35-260 or maybe 45-245.

You know thinking about stuff,go over your connections and maybe it;s something goofy with the red light being off and you lost a power and/or ground connection.

I took apart a sending unit years ago and basically it is a wiper arm that goes across windings of wire on an insulator and then one end of this wrapped wire goes to ground.

408981

408982


Jim
 

·
Registered
Joined
·
235 Posts
I'm hopin to fix mine this weekend and when it's full it reads full...the speedway part will be here soon ...today I hope ...will fill up the tank and adjust it to full on the gauge...full now is at 3/4 tank on the gauge...just another bug to fix until I totally de bug it...(will use gas cans to fill it so no gas is burned) at home...usually do that anyway
 

·
Registered
Joined
·
423 Posts
Quote -" It was reading just under half at the time. I dug out the instructions and I started messing around with the potentiomter settings and next thing I new it stopped working all together no led light. I know the gauge is ok because when I removed the module and hooked the gauge back up it reads full."

I'm wondering if Custom Jim might be onto something when he suggests a possible wiring issue. I say that because your gauge should not be reading full (that assumes you're still at hall tank and still using the 0-30 Ohm sender), especially with the Interface Unit out of the circuit because you don't have the resistance to drive a "full" reading. That and the red led disappearing.

Try removing/lifting the tank sender ground and see if the needle reflects any change. Likely won't.
Assuming it doesn't, create a new known good ground point from tank sender to body or better yet, tank sender to battery post (would be the absolute best) and bypass the current tank sender ground to body - don't discard the old tank sender ground just yet.

Positive result?
If yes, focus on the tank sender ground. May even be a problem inside the tank (sorry).

Same result?
At the feed into the interface module unit from the tank sender Pin 3 (yellow), lift the yellow lead and connect to a test probe from your Ohmmeter. Connect the other Ohmmeter lead to the tank sender ground point (think of it as measuring a physically long resistor). What is the value measured at the yellow lead? Should reflect approximately 15 ohms (half tank on a 0-30 Ohm tank sender)

If yes, re-connect all the interface module leads. Apply switched 12VDC and measure with your voltmeter between Pin 5 and Pin 1. You should see 12VDC. If no, your Pin 1 ground lead is bad.
If yes, try readjusting the interface module again. You are using Type 7 custom DIP switch settings, it's assumed.
Let us know what you see.
 

·
Premium Member
Joined
·
3,487 Posts
Discussion Starter #10
I removed the interface module- I should be able to simulate a test with a 12 volt battery and the sending unit that was sent with the gauges. Went to a cruise in last night. " somebody" mentioned that maybe we should stop for gas- well I over filled it- ugh which led me to realizing I missed installing the hose clamp that goes on the rubber fill tube ( do I dare say interface rubber? lol). Once we got back home I fixed that little bug. the joys of hot rodding:rolleyes::D.
 

·
Premium Member
Joined
·
3,487 Posts
Discussion Starter #11
I'm hopin to fix mine this weekend and when it's full it reads full...the speedway part will be here soon ...today I hope ...will fill up the tank and adjust it to full on the gauge...full now is at 3/4 tank on the gauge...just another bug to fix until I totally de bug it...(will use gas cans to fill it so no gas is burned) at home...usually do that anyway
Please read you instruction a few times- They do recommend starting with an empty tank and add a few gallons before setting your needle to empty- that way you have a bit of a cushion when yo are reading empty at a later date.

Let us know how you make out.
 

·
Premium Member
Joined
·
3,487 Posts
Discussion Starter #12
Jim- yes they are a pretty simple set up. Hopefully I will have some time tonight to have a look at this again.
 

·
Registered
Joined
·
235 Posts
Please read you instruction a few times- They do recommend starting with an empty tank and add a few gallons before setting your needle to empty- that way you have a bit of a cushion when yo are reading empty at a later date.

Let us know how you make out.
thanks that's good to know don't have the device yet
 

·
Premium Member
Joined
·
3,487 Posts
Discussion Starter #14
well I just checked the interface module by hooking up to my battery. No led so I think it may be toast. I could possibly mount the universal sending unit rehostat to my sending unit in the tank but that will be another day as my tank is full.
 

·
Registered
Joined
·
235 Posts
well I just checked the interface module by hooking up to my battery. No led so I think it may be toast. I could possibly mount the universal sending unit rehostat to my sending unit in the tank but that will be another day as my tank is full.
did you have to remove the instrument cluster or crawl under the dash and wire it
 
1 - 15 of 15 Posts
Top