Hi I have a 1998 Chevy 2500 crew cab ls swapped I can’t get the gas gauge to work it’s stuck past full.

[Braydenw958]

I checked grounds at motor, and frame near fuel sending unit. I did a continuity test from purple/white wire at sending unit to pcm at pin 54 then a continuity test from pin 38 purple wire to gauge.

When off I’m getting 124ohms from sending unit at pcm then 36ohms from gauge at pcm When running im getting 1.5v from sending unit at pcm then 9volts from gauge at pcm and if I put them together and bypass the pcm it reads 28ohms off and 9volts running all sequences still show full when pcm bypassed it dances around a little bit but still on full. And if I ground the wire going to gauge it goes to empty

 

[Cadillacmak]

Is the PCM from the LS? You have to make sure its set up in the programing for your truck not the one it came out of.

 

[Braydenw958]

That’s what I thought but I looked up a 2002 sending unit because that’s what the pcm is out of and the ohm ratings for the sending units are the same but now I’m questioning the 5v reference gray wire because the purple/white wire is only 1.5volts I’m wondering if that’s to low and when i got the truck it was already ls swapped and the gauge was stuck on 1/2 now it’s stuck on full forgot to put that in there as well

 

[Braydenw958]

And Somebody removed the fuel pump balance module so I’m wandering if that’s the problem

 

[Braydenw958]

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[Braydenw958]

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[Cadillacmak]

I am not 100% sure here, but you might have to pin it like the express van into the computer and change the values to express van values. If your missing a module? I would have to really research it.

 

[Braydenw958]

I got 5 volts coming out of the pcm to to the purple white so my test was a bust it turns into 1.74v when I hook it back up

 

[Braydenw958]

I am not 100% sure here, but you might have to pin it like the express van into the computer and change the values to express van values. If your missing a module? I would have to really research it.

I think y’all might be right I’m researching now lol