SERVICE MANUAL UPDATE - SEC. 7 TRANS. UNIT REPAIR INFORMATION

SUBJECT: TRANSMISSION UNIT REPAIR INFORMATION

MODELS: ALL 1992 LIGHT DUTY TRUCKS WITH HYDRA-MATIC 4L60 TRANSMISSION

The following represents new product information for Section HYDRA-MATIC 4L60 in the 1992 Light Duty Truck Unit Repair Manual. This information has been updated since publication of the 1992 Service Manual and should be noted accordingly. Be certain to familiarize yourself with these updates to properly repair the 1992 HYDRA-MATIC 4L60 transmission.

On August 14, 1991 (Julian Date 226), the HYDRA-MATIC 4L60 transmissions were built with a new calibration that changed the TV limit line-up.

The changes included a new TV limit valve (332), a new TV limit valve spring (331), and eliminates the TV limit plug (351). Also included is an updated line pressure check chart and an updated 2nd apply piston and housing application chart.

Update your 1992 Service Manual with the following three (3) pages.

o Cover (15) for porosity or damage. o Seals for: - Nicks or cuts. - Freeness in the seal groove. o Springs for distortion. o Pin for wear or burrs.

Important

o Check servo bore in the case for any wear which may cut the servo seals.

Measure Figure 121 1. Measure piston (25) dimension *A. 2. Measure housing (22) dimension **B. 3. Check model application.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.