Fuel gauge help

[Lextech]

Thanks for the info, I have all the wiring figured out,,, lex answered the reason why I can't get the gauge to work........... now I just need to figure where to pin it on the new PCM

The Purple wire goes to PCM C2-38. The Purple/White wire goes to PCM C2-54

Jeff

[1991SSP]

thanks jeff!!

[kewljay223]

There are several settings in the PCM for the fuel gauge. Two of those settings definitely need to be changed for the Gen3 calibration to properly run the 98-2000 GMT400 gauge. I have no idea if your wiring is correct. Assuming it is, and your gauge works, then it is in the tune.

Jeff

you say 98-2000 but what about the earlier years? i have a 95 that im about to swap a 03 lq9 in. will i be running into this same issue? will the tune need to be adjusted just like this or is it different? im not sure if the gauge gluster is the same.

[Lextech]

The fuel gauge info does not come from the PCM on the 97 and earlier trucks. It goes from the fuel sender to the gauge. It only goes through the PCM on 98 and up trucks.

Jeff

[1991SSP]

All I can say is this site is a blessing for anyone doing a swap... I always love a challenge and learning new things...

[kewljay223]

The fuel gauge info does not come from the PCM on the 97 and earlier trucks. It goes from the fuel sender to the gauge. It only goes through the PCM on 98 and up trucks.

Jeff

OK. thats good info but i forgot to mention that i will be running a fuel sending unit from a 98 truck because it has the fuel pressure sensor built into the assembly and i need it for smog. my 95 doesnt have it due to it being obd1. so i guess my question now is does that sender only to go through the pcm or will there be two wires out of it? one for the pcm (evap tests) and one for the gauge? if so is the calibration on the sender correct for my gauge or will i need to do the resistor thing (100ohm?)