2003 GMC Jimmy. v6 Vortec 4.3 liters. Question: I've owned the Jimmy for about three years, haven't had to do a tune up yet. I would like to know what i need to get it done. I have no major complaints to report. Being used to owning old vehicles that needed tuned at least once a year, kinda got spoiled with this GMC truck.

 

Answer: Nothing extra special to do on this truck than any other vehicle. A major tune up would require replacing the air filter, spark plugs, spark plug wires, distributor cap and rotor, fuel filter, PCV valve, inspect the ignition coil, check all fluid levels and condition. If over 100k miles, suggest getting the transmission fluid and filter changed, coolant flushed and brakes inspected, as well as front end and steering components. Inspect the belt for cracking and wear, check the tires and battery and inspect for any leaks.


1996 gmc jimmy 4x4. 4.3 Vortec.
Question: I am a truck mechanic but this has stumped me i hook up to my obd2 scanner the scanner powers up ok truck runs fine starts fine but obd says unable to find system engine light on airbag light on .

 

Answer: You have a Class 2 Serial Data Line problem. The power and ground work ok at the diagnostic port, but you've lost the serial data signal where the scanner can 'talk' to the vehicle. It can't find anything because it's getting no response on the data line. If you could pull codes, you'd probably find a few U1000 codes with loss of communication to whatever module can't connect with the others. This problem could be due to a broken wire, a bad connection, or even a bad module such as the PCM or SDM (airbag module). Since you have a check engine light and an airbag light, I'd start looking in that direction first. You can try disconnecting modules one at a time to see if the problem goes away and then you'd know what to replace or where your problem area is located.

 


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    Car and Truck Fuel System Operation

    The fuel tank stores the fuel supply. The electric fuel pump, supplies fuel through an in-line fuel filter to the fuel injection system. The fuel pump provides fuel at a higher rate of flow than is needed by the fuel injection system. The fuel pressure regulator maintains the correct fuel pressure to the fuel injection system. A separate pipe returns unused fuel to the fuel tank.

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