Also you can see a free round connector in the picture. It's a big red wire and I don't know what it is used for because it was there when I bought the truck. Maybe the starter wire they changed and left the older there....not sure.

Response from Takwakin
1 question asked

Shorted fuel gauge, wiring, or sending unit.

Answered by rivermikerat (expert)
5,495 answers provided

I would need the location of connectors so I can test it. I have the full wiring diagrams but don't show the exact location of the connectors.

Response from Takwakin
1 question asked

Purple wire on instrument cluster connector, pin 29 to fuel level buffer module, pin L, under the cluster. The schematic I have doesn't show any intermediate connectors. Instrument cluster, fuel level buffer module, engine control, and pump. Pump is in the top of the tank.

Answered by rivermikerat (expert)
5,495 answers provided

Ok thank you I will give it a try but before I will get the diagram location because pin L, pin 29 and purple....it don't give me the exact location. For now with the connector underhood unplugged the truck run fine. Also do you know what is the exact usage of this connector?

Response from Takwakin
1 question asked

I'm not sure about the connector. But, there is a set of wires that runs to the engine control module for the pump from the fuel level buffer module. I'm guessing this might be the wires/connector you disconnected.

Pin 29 is on the instrument cluster. The dash gauges. Where the speedometer and fuel gauge are.
Pin L is on the fuel level buffer module. It's behind the dash in the center.

Answered by rivermikerat (expert)
5,495 answers provided

What is the usage of this fuel level buffer module? Nothing seems to change when its unplugged except the needle not showing the fuel level?

Response from Takwakin
1 question asked

I'm not sure, because there's nothing definitive in my reference, but I would say voltage stabilization. I think that's why when you unplugged the wires from it to the engine control, things went back to normal.

Answered by rivermikerat (expert)
5,495 answers provided

I printed the 4 pages for wirings of engine but from a Jimmy 1997 instead of a Blazer so the wires are not the same color. I have to find what is where prior to further testing.

Response from Takwakin
1 question asked

Here.

Answered by rivermikerat (expert)
5,495 answers provided