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Randy, GMC Technician
Category: GM
Satisfied Customers: 9794
Experience:  25 Years experience
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GM Savana: I have a 1998 gmc savana conversion van and the

Customer Question

I have a 1998 gmc savana conversion van and the transmission shifts fast
Submitted: 2 years ago.
Category: GM
Expert:  Randy replied 2 years ago.
Hi, my name is***** will assist you. You will need to scan the on board diagnostics and retrieve any codes that are present. The fast shift points may be due to an electrical component failure such as the TPS.
The 4L80-E transmission uses 2 electric shift solenoids to control transmission upshifts and downshifts. In addition, a pressure control (force motor) solenoid controls hydraulic line pressure, and a Torque Converter Clutch (TCC) Pulse Width Modulated (PWM) solenoid is used to control fluid acting on converter clutch valve, which then controls TCC apply and release. Solenoids are turned on and off by a Vehicle Control Module (VCM).
VCM receives signals from various transmission sensors. Sensors include engine speed and throttle position, transmission speed, hydraulic pressure and transmission fluid temperature. VCM has on-board self-diagnostics to help identify any parts or circuits which may need further testing.