2000 Chevy Silverado 1500, LS 4X4 extended cab. 5.3 vortex, auto tranny. 185000 miles. Recent know situations: Number two knock sensor DTC. Replaced sensor and replaced the wire assembly. Now get number one knock sensor (dummy me didn't change that one too). No other DTC's before or after knock sensor #2 issue or even currently. Easy starting and steady idle. No abnormal noise other than a ticking believed to be coming from a loose exhaust. New muffler installed a while back. Had tranny flushed and new filter and fluid at dealer. Recently replaced fuel filter. Plugs and wires a while back. Should be in good conditions. Been through several tanks of gas from differnet gas stations with same issue I am about to explains. THe issue: Just me and truck, no towing or any load. Driving 65 +/- 5 MPH on 4-lane highway. Low grade incline (small hills) I no longer have to power to make them while in overdive. Will shift down and does fine. Actually causes truck to gain speed well on the hill. While in overdive, I press the gas pedal and still lose speed in overdive until it shift down. Did not do this before. Checked all sensor pigtails for cleanliness, good on fluids. Brakes not binding, the do not heat up. air filter clean, no obstructions. throttle linkage operates smooth. Have not checked fuel pressure yet. Have a cool reader/scanner coming in the mail that reads live data. Looking forward to seeing what is going on at idle and on the road. Any ideas as to why this truck will not hold it's own on the hills like it used to? By the way, When I changed the spark plugs, I went with the replacements iridium (.40-gap) that replaces the platinum (.60-gap). TSB #03-06-04-060 - (10/24/2003). What do you think?

Try manuals.com it's free and they usually can help me . Good luck !

Yes we can ! With the light on and or flashing , DTC'S - diagnostic trouble codes are stored in the 4X4 control module . Have the codes check , not at auto zone or any other parts stores . There code reader tool will not pull this codes . Need to take to a qualified repair shop . Testing also needs to done , not guessing an throwing parts at it . This 4X4 system can set a number of codes .
DTC B2725 ATC Mode Switch Circuit Malfunction
DTC C0300 Rear Speed Sensor Malfunction
DTC C0305 Front Speed Sensor Malfunction
DTC C0308 Motor A/B Circuit Low
DTC C0309 Motor A/B Circuit High
DTC C0310 Motor A/B Circuit Open
DTC C0315 Motor Ground Circuit Open
DTC C0323 T-Case Lock Circuit Low
DTC C0324 T-Case Lock Circuit High
DTC C0327 Encoder Circuit Malfunction
DTC C0362 4LO Discrete Output Circuit High
DTC C0367 Front Axle Control Circuit High
DTC C0374 General System Malfunction
DTC C0376 Front/Rear Shaft Speed Mismatch
DTC C0387 Unable to Perform Shift
DTC C0550 ECU Malfunction
DTC C0611 VIN Information Error

DTC C0387 Unable to Perform Shift
Circuit Description
The transfer case encoder is a switch that converts a shaft position, representing a mode or range position, into electrical signals for use by the transfer case shift control module. The encoder houses 4 Hall effect sensors that are used for channels P, A, B, and C. These sensors provide a path to ground, when a magnet, (part of the Motor Encoder), passes over them.
The transfer case shift control module supplies an 8 V reference and a ground circuit for the encoder hall effect sensors to function.
The transfer case shift control module supplies current limited 5 V on all the channels, thus as these channels are pulled to ground, the module can interpret the location of the transfer case shift position.
This DTC detects that the transfer case is unable to successfully complete a shift to a requested mode or range.

did ya look into the trans mount or trans mount bracket

It is recommended that you change the oil every 3000k miles.

It could be that your knock sensor circuit is working perfectly.You may have a knock that it is reading for long periods.
Try running it disconnected, and see if there is a clatter or knock when accelerating lightly.

You could have a vacuum leak.

try selecting from nutreul or less then 3km

it should be a 4L60E.

on the 4.3l version the knock sensor is on the back left side of the engine right by the bell housing. on the bigger engines they are below the intake manifold in the engine valley

the knock sensor on V6 models are threaded into tranny mounting flange just below the oil pressure sending unit. On V8 models it is under the Intake Manifold.

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2000 Chevy