1999 GMC Sierra - Page 8 - Answered Questions & Fixed issues

Check that the orange wire in the right side of your steering column is not cut or broken. It has 2 conductors in it. When they short together, it will turn the tow/haul function on or off each time. If they don't touch each other, the tow haul function won't activate.

Is the vehicle running rougher since the tune up and such ? Is it worse since fuel filter change ? Was there any change good or bad since the work was done ? Is the fuel line leaking gas ? Do you remeber what code AutoZone came up with ? I'm just trying to get all the correct information so I can give you the best guess as far as what your problem could be. Also what size engine do you have ? Reply/comment here or you can email me directly at [email protected]. I don't mind helping if I can and there is no cost but as I said need as much info as I can.

sounds like the wire has an internal break or is shorting.replace it and also check ground wire on this circuit. continuity test the wires as a way of determining circiut is closed. bottom line is someting is loose or damaged and doesnt complete the circuit.old fashioned testing the wire will probably lead to an answer

Try disconnecting the battery for a few minutes to reset the computer and see if that helps.

fuel pump or fuel pump relay

Below is a general description of the problem. Check the following possibilities and we can go from there. DTC P0430 - Catalyst System Efficiency Below Threshold (Bank 2) Description Indicates Bank 2 catalyst system efficiency is below the acceptable threshold. Possible Causes Use of leaded fuel Damaged Oxygen Sensors Malfunctioning ECT High fuel pressure Damaged exhaust manifold Damaged catalytic converter Oil contamination Cylinder misfiring Downstream Oxygen sensor wires improperly connected Damaged exhaust system pipe Damaged muffler /tailpipe assembly ******** spark timing

If it is so equipped, its located on the back side of the engine. Just to the left of the Intake manifold. You can trace the pipe running from the passenger side exhaust manifold up to it. It is a small roundish steel canister with a wiring plug and vacuum line attached.

Make the FixYa experience better for everyone by voting.The problem can be anything from a faulty cranshaft or camshaft sensor to bad fuel pressure regulator. The only way to properly diagnose the problem is to take you vehicle to the closest AutoZone and get a free diagnostic scan.All the best,Ben

Read thru this link. Should help you outhttp://vatspasslockpasskeysecurityhelp.yolasite.com/

All the illumination lights? May be the headlight switch, fuse or the dimmer knob is rotated too far and it turned them off.

If you are at or near the 100,000 mile mark then your fuel pump may have failed. If you remove the fuel filler cap and listen carefully at the filler neck while someone turns the ignition key to "run" [don't actually crank the engine] you should be able to hear the fuel pump buzz for about a second and a half as the key is turned On. If you don't hear the pump buzz then odds are your pump is dead. Your pump may have actually failed making it appear as though you ran out of fuel. Not to uncommon. Hope this helps and good luck!

Before assuming the heater core is blown check the following.1. Check coolant level while engine is cold.2. Leave the radiator cap off and let the engine run. See if you can see the coolant circulate when the engine is brought up to temperature.3. Check the temperature gauge inside and note if the engine temp is correct.4 Does the engine overheat?5. Feel the heater hoses and check if they get hot.6. Can you smell antifreeze inside the cab?Start here and let me know.

First I suggest check the fuses, than wires and ground connections.

I hope this helps; keep in mind that your feedback is important and I'll appreciate your time and consideration if you leave some testimonial comment about this answer.

Thank you for using Fixya, and have a nice day.

Hello! If your Sierra is equipped with a Heater Control valve it is near the firewall located in the inlet heater hose...From 1999-2000 a change was made and your vehicle may not use a HCV ...If it is there, here is the part # and price...

ACDELCO Part # 155686...$20

Send symptoms of the problem in a comment if you are having an issue with heat and a HCV isn't installed on your vehicle...Guru...........Saailer
I’m happy to help further over the phone at https://www.6ya.com/expert/david_6df67de3b14de867

The code is usually in a tag inside of the glove-box (door). If it has to be wiped off, do it carefully. Thanks for using Fixya.

Common symptom of faulty sending unit in tank.Remove tank and replace sending unit

The fuel sender is with the pump module assy. You say the fuel pump is new, did you replace the fuel module or just the pump? is this a new problem after you replaced it or was it there before? Never replace just the pump.

The fuel filter is about a foot away from the fuel tank on the driver's side of your truck. Just follow the fuel line from the gas tank. It is an inline filter about 4 inch long cylinder about 2-3 inches thick.

Their code reader may only be good for generic codes where yours may have vehicle specific code(s) stored. Need to have a shop hook up a shop scanner.

yes, all you need is the adaptor, there are all kinds of adaptor they will give you a 6pin adaptor that plugs in and then has the 4pin to connect too. good day. also you can go to an auto part store or a uhaul moving store they sell tell also, let me see if i can give you a picture of it to help you. good day.