The next step would be to see if the PCM is getting the proper information from the fuel level sending unit. If it is not, then the wire from the sending unit to the PCM is compromised. If it is, then there is likely a problem with the cluster.

 

Any chance you reversed the "grounds" when you put the new plug on? Not everything is ground. On the fuel sending unit black (chassis ground) goes to the pump, black/white (supplied by the VCM) goes to the fuel level sender. You're correct in that here is no direct connection from the gauge to the sending unit, it's computer logic and if the network connection was bad you'd have more issues. Go to Radio Shack and buy a small resistor, anywhere between 100-150 ohms, plug it into the harness at the fuel tank between the purple & black/white. You might have to loosen the tank clamps to get at the plug but it can be done without dropping it (been there). If the wiring is good, when you turn the key on your gauge will rise and low fuel light will be off. 35 ohms duplicates an empty tank, 235 is a full one. If that doesn't work - leave the resistor in place & turn the key off, disconnect the CLR plug from your VCM and with an ohmmeter check between pins 13 & 19 of that connector. You should "see" that resistor. If you don't then it's definitely a wiring problem, open or dead short will make the gauge read Empty. Use small paper clips as probes to attach to, don't distort the connectors. Also, in that same connector (CLR) - if you turn the key on to the RUN position, with a 12v test light connected to ground, probing pin 2 should light it and would also fire your purge solenoid valve. If it doesn't light it's a wiring problem, bum solenoid/connection or check ENG 1 fuse in the underhood fuse block. Also did you see any corrosion (white crap) when you pull the plug off the VCM? Not a likely thing because the wires involved aren't proximate but I saw a badly sealed one once.

 

I ran brand new wires and checked for faults. I also took the cluster out of a buddies blazer (same year and model, working perfectly) and put it in mine...Gauge still on "E".

 

Thanks for the tip on testing the solenoid. I will test that tomorrow. You mentioned an open circuit or dead short causing the gauge to read "E". Wouldnt a dead short cause it to read "full"?

 

Think so wouldn't you? I go back to the old days too, ground the sending unit wire to pin the gauge. It's different now, sending unit connects to the VCM and the VCM sends information packets over the computer network to the dash cluster. On mine I had the harness out between the frame and body so I could plug the resistor in and watch my gauge. That's how I figured out both open and shorted makes the fuel gauge go to "E" First thing I tried was a piece of wire to dead short it. Then I took another sending unit to ohm out the range and figured out the resistances. (my buddy gave me a few, replaced his pump, replaced it 2 months later 'cause he didn't change the filter, replaced that E-bay pump a year latter) Anyhow, that's how I came up with the resistor technique for checking the wiring.

 

hey yall i need the pin specs for the pcm just like below me but only for a 96 blazer 4.3l 4 door 4wd i wouldgreatly appriceate it. thanks guys

 

gracias por la informacion, reparo mi troja

para blazer 1995, sirven

 

This thread is specific to a 2000 so that would not apply to a 1995.

Also, this forum uses English as the primary language. As such, if you wish to request help, you may want to get your request translated as best as you can.

 

Hi Sir. Will you have the pinouts for a 96 Blazer 4x4? I will need to fabricate my own harness as mine is fried. Thanks. so much.

 

Does anyone have this in a format larger than it's current size ?