Problems With a 4L60E Transmissionby David Reber
The 4L60E is a four-speed, electronically controlled automatic transmission used in light-duty trucks made by General Motors (GM). Though most automatic transmission diagnoses and repairs are beyond the scope of the home mechanic, you can diagnose some common issues without specialized tools or training. Usually, such diagnosis simply means recognizing and isolating the symptoms of a specific malfunction, which can help you decide which repairs are really necessary.
Problems with Reverse Gear
The 4L60E's reverse gear engages slowly, slips or fails to engage when the reverse clutches become worn out. ther causes of this problem include a broken sunshell or a fluid leak in the reverse hydraulic circuit. Some fluid leak issues may require only minor repairs, while worn clutches or other broken parts require removal and repair or replacement of the transmission.
If the transmission fails to upshift, or does so only when you release the throttle, it may indicate a problem not with the transmission itself but with the throttle position sensor (TPS). The TPS, located at the engine throttle shaft, relays information to the transmission to facilitate proper shifting. The TPS is inexpensive and easy to replace.
Lack of Third or Fourth Gear
A lack of third or fourth gear operation often points to a worn-out clutch. In this case, you must likely remove the clutch for repair or replacement.
David Reber has been a published writer since 1991. His work has appeared in the Kansas Herpetological Society newsletter and in "Amphibian and Reptile Conservation." He teaches high-school science and maintains a menagerie of classroom animals. Reber holds a Bachelor of Science in biology from the University of Kansas and a Master of Science in education from Emporia State University.