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Tahoe & SuburbanThe power, space, and brutal towing ability make the Tahoe and its longer sibling, the Suburban, arguably the best full size SUV's on the market today.
Hello guys, I have a 02 Tahoe z71 5.3 with the flex fuel. When I bought it everything worked fine however my dad was driving it down when he lost all power. Long story short it was the PCM fuse.(thats not the name of the fuse obv). That fuse also goes to the flex fuel sensor. We’ve replaced that fuse and no problems except now I have a code for the flex fuel sensor. It’s a low voltage code. I’ve probed all the connections on the flex fuel sensor wire and I have a good ground, and good 5volts from the white wire. However no 12v on the power wire. What would yall do from here? The car runs like crap since this has happened.
According to the description and operation section, the flex fuel sensor has a 3 wire interface, with the wires being power (+12V), GND, and the PCM output of the sensor. The PCM side puts a 5V signal on here, and the sensor pulls it down to ground to send its digital signals.
The connector diagram below indicates the 12V (pink wire) should come from "circuit 439" i.e. ignition 1 voltage.
Digging around in the wiring diagrams, I find circuit 439 on this diagram, going to both the PCM itself, and to the "Fuel Composition Sensor".
Ok thank you a lot. Here’s what I did. (Mostly just to test to see if I can even fix it so it’s just temporary) I cut the power wire off the connector and ran a new one directly to the battery. And I retested the voltage on the harness. Bad ground as well. So I cut that and permanently grounded it to the frame. Cleared the code. And to my surprise it actually fixed it. No more rough starts and bad gas mileage. My question now is how would I go about permanently fixing this? Obviously re running the wire to the fuse block, however how will I know what wire it is? Thank you for your responses!
I guess I would try and trace the ground and pink wires back from that connector as far as you can, to see if you can find where the failure point is. It has to be at another connector in the wiring harness, or a grounding point. Ground failures are very common.
The charm.li website has ground and power distribution diagrams for your vehicle, and you might start there.
Ok I’ll have to do that tomorrow… however I now have a code for an O2 sensor bank 2 sensor 2. It’s the one that twines into the wiring for the flex fuel sensor. It’s a low voltage code. Could it be because I cut the power and ground wire for the flex fuel sensor? Do I just have to ground out the ground wire I cut?
Stupid flex fuel
