Question about 2004 GMC Envoy

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Thanks! and another question?

Thanks Pyrhyc, I recently had the transmission flush and the oil changed at Jiffy Lube. Is it possible that the wiring to these sending units may have been disturbed during that service? Are the sending units close to either of the areas in question?

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  • gusmankan Jul 30, 2008

    Thanks again for the quick response! The vehicle is actually the 2004 GMC Envoy XUV. I didnt see this option in the vehicle list so I picked the closest one. The instruments appear to be all in one or an "instrument cluster". I appreciate your help as I am off work today and am trying to find a fix as quickly as possible. I am going to check the transmission for a broken or loose connector right away! Thanks again..

  • gusmankan Jul 30, 2008

    Thanks again Pyrhyc... I tried to locate the speedo and or the oil sending unit... No luck on either one!!! This engine is the Vortec 4200 straight six cylinder and it really is buried in wire and plastic covers... I went under the vehicle to check the trans and it has a very strange offset drive due to the 4 wheel drive and the long engine.. Needless to say there are ALOT of electrical plugs and wires there. I could not distinguish which one may be the speedo. I also tried to find the oil pressure sending unit and found 2 different connectors that I thought might be it(one just above the oil filter and one near the top front of the engine passenger side) I disconnected each, one at a time and started the engine but did not loose my oil pressure reading(which appears to be working normally now) AAARRRRGGGGHHH....Any way I do appreciate your help and suggestions. I am now going to try and find an engine specific manual or something to see where the oil sending unit is and see if I can even get to it!



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With the tranny flush, yes. It's possible that they may have knocked the connection loose or broke it at the sending unit. The unit is usually located on the side near the bottom ot the tranny. With the oil change I'm going to say no. The oil sending unit is generally located on the driver side, center of the engine block near or under the exhaust manifold, or on the front of the block towards the top. Unless they moved them on me, it shouldn't be anywhere close to the drain plug on the oil pan, and there no way that they should get near the oil sending unit when changing the oil, unless the sending unit is near the oil filter, and GMC generally doesn't put the two near each other for this reason. Just thought of something. Are the gages individually replaceable, or are they all built into one display unit?

Posted on Jul 30, 2008

  • Ryan Rogers
    Ryan Rogers Jul 30, 2008

    If the instrument panel is an all in one, these work off a central control board built into the cluster or panel. If the board has malfunctioned on these two gages, then unfortunately, the entire cluster will need to be replaced. If this is the case, I recommend your local salvage yard, or an on line locator for parts at salvage yards nationwide. This item is expensive at a dealer!!!

  • Ryan Rogers
    Ryan Rogers Jul 30, 2008

    If you're going to buy a manual, I suggest a Haynes or chilton, you can get them at any automotive parts store, and it will be the best $20 investment on your Envoy. It will have the exact location for the units and the color of the wire. I prefer the chilton, it's more user friendly, but both are fine manuals.



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unfortunately sometimes when you get the engine or transmission flushed it can cause an oil leak I don't know what it will cost but I would be getting other quotes & get the work done at the cheapest quote, it pays to shop around........hope this helps......cheers.

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