Hooking up 97 fuel gauge to 12200411 PCM

[OBSGuy]

On my 1998 Chevy K1500 I'm working on I have around half a tank of gas, the voltage is reading 2.7V at tank and at PCM in, but only around 1.5V on the wire that runs from the PCM to the garage, but with gauge out there is nothing on the plug behind the cluster. What should the voltage be on the wire from PCM to the gauge?

 

[AK49BWL]

The voltage from the PCM to the gauge is PWM, so it varies - but as I recall, it's a ground sink, not a hot lead. So checking it without the gauges in would show 0.

 

[Jayss88]

Just gonna leave this here in case anyone else wants to do this, or ends up with a 98+ Vortec swap on an earlier truck.

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Those sender values will get you into the right ballpark, but I will be the first to admit they're not perfect, and I haven't really bothered trying to get them perfect.... Your gauge will show empty when you have about 4-5 gallons left, but from full to half-tank, isn't too far off.

On the other hand, I spent several hours getting the gauge output PWM table right, so that one SHOULD be just about perfect.

Been messing with this for days now. Have hp tuners. Got everything working but my fuel gauge. Copied your table and same thing gauge. Key on and gauge is pinned all 1/2” past full key off stays right at full and theres a little over half in the tank. Suspected sending unit, replaced it same thing. With half tank when i hit the brakes and sloth fuel i can see gauge flick down towards full some. 0411 computer lq4 swapped 98 k1500

 

[Astro]

Been messing with this for days now. Have hp tuners. Got everything working but my fuel gauge. Copied your table and same thing gauge. Key on and gauge is pinned all 1/2” past full key off stays right at full and theres a little over half in the tank. Suspected sending unit, replaced it same thing. With half tank when i hit the brakes and sloth fuel i can see gauge flick down towards full some. 0411 computer lq4 swapped 98 k1500

That sounds like the sending unit is still routed directly to the gage vs the pcm.

 

[AK49BWL]

No, you can't use my table in a 98+ because they use 40-250 ohm senders. 97 and older use 0-90 ohm senders.

 

[L31MaxExpress]

No, you can't use my table in a 98+ because they use 40-250 ohm senders. 97 and older use 0-90 ohm senders.

98+ should work with the van table fairly accurately. On my 99 Tahoe, I added fuel in 1/4 tank intervals from Empty when I swapped to the 0411 run 8.1L and was fairly accurate. However I purposely skewed it to correct it to where it read accurately from what I consider "Empty" to Full. For reserve capacity sakes, I purposely put Empty with 7 gallons in the tank. So my gauge basically shows the 31 gallon tank as E=7 gallons, 1/4 =13 gallons, 1/2=19 gallons, 3/4= 25 gallons, Full = 31 gallons. Hard to ever run out of fuel that way or find yourself in a bind getting close to running out if you fill it up at E. The Delphi sending unit in the Express van is the same way, shows E with about 8 gallons left. Also took about 6 gallons to make the 87 G20 show fuel in the 33 gallon tank with the Spectra sending unit in it.

For those of you wanting to keep a 1/4 tank in your tank because your truck does not have the later venturi bucket pump, it is easy to make the gauge read empty at 1/4 tank and make the remaining ~3/4 tank make the gauge read the full sweep E-F.