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GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 15201
Experience:  GM Grand Master Technician 2007. 14 years experience.
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97 chevy silverado, CEl on code po758, but both

Customer Question

***** *****, 97 chevy silverado, CEl on code po758, but both solenoids have correct resistance and operate when 12 v is applied.
JA: Thanks. Can you give me any more details about your issue?
Customer: trans does not have 1st gear or 4th, only 2nd & 3rd
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Submitted: 1 year ago.
Category: Chevy
Expert:  Roy replied 1 year ago.
good evening my name is ***** ***** I will assist the code is all about the 2-3 shift solenoid and circuit. I will attach the description for the code. what have you done so far?? I see you have applied power to the solenoid. was it removed when you did this to verify it is working or was it still installed?? Roy Circuit Description The 2-3 Shift Solenoid Valve (2-3 SS Valve) controls the fluid flow acting on the 2-3 shift valves. The solenoid is a normally-open exhaust valve. With the 1-2 Shift Solenoid Valve (1-2 SS Valve), the 2-3 SS Valve allows four different shifting combinations. The solenoid attaches to the control valve body within the transmission. The 2-3 SS Valve receives ignition voltage through circuit 1020. The VCM controls the solenoid by providing the ground path on circuit 1223.When the VCM detects a continuous open or short to ground in the 2-3 SS Valve circuit or the 2-3 SS Valve, then Diagnostic Trouble Code (DTC) P0758 sets. DTC P0758 is a type A DTC.Conditions for Setting the DTC The system voltage is 10-19 volts.The engine speed is greater than 450 RPM for 8 seconds.Not in fuel cutoff.All of the above conditions are met for 5 seconds and either of the following fail conditions occurs for 5 seconds:The VCM commands the solenoid ON and the voltage remains high (B+).The VCM commands the solenoid OFF and the voltage remains low (0 volts).Action Taken When the DTC Sets The VCM commands third gear only.The VCM commands maximum line pressure.The VCM freezes shift adapts from being updated.The VCM inhibits TCC engagement.The VCM illuminates the Malfunction Indicator Lamp (MIL).Conditions for Clearing the MIL/DTC The VCM turns OFF the MIL after three consecutive ignition cycles without a failure reported.A scan tool can clear the DTC from the VCM history. The VCM clears the DTC from the VCM history if the vehicle completes 40 warm-up cycles without a failure reported.The VCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the VCM.Diagnostic Aids Inspect the wiring for poor electrical connections at the VCM. Inspect the wiring for poor electrical connections at the transmission 20-way connector. Look for the following conditions:A bent terminal.A backed out terminal.A damaged terminal.Poor terminal tension.A chafed wire.A broken wire inside the insulation.When diagnosing for an intermittent short or open condition, massage the wiring harness while watching the test equipment for a change.Test Description The numbers below refer to the step numbers on the diagnostic table. This step tests the function of the 2-3 SS Valve and the Automatic Transmission Wiring Harness Assembly.This step tests for power to the 2-3 SS Valve from the ignition through the fuse.This step tests the ability of the VCM and the wiring to control the ground circuit.This step measures the resistance of the Automatic Transmission Wiring Harness Assembly and the 2-3 SS Valve.