SERVICE PROCEDURE POLICY CHANGES

SUBJECT: SERVICE PROCEDURE POLICY CHANGES

MODELS: 1991-92 C/K, R/V, AND P TRUCKS AND G VANS WITH 4L80-E/4L80-EHD TRANSMISSIONS

This bulletin covers changes to the HYDRA-MATIC 4L80-E/4L80-EHD Service Policy for in warranty vehicles. This bulletin does not apply to out of warranty vehicles. The only service options available will be as listed below. SRTA models and service parts can be ordered from your local General Motors Service Parts Operations (GMSPO) Parts Distribution Center.

New Service Policy Permits On-Car Service or SRTA Only.

ONLY limited on-car repairs or SRTA will be the service options available for vehicles currently covered under the warranty period.

Conditions when SRTA usage is appropriate: Any repairs that cannot be completed by replacement of the parts shown in Figure 1.

Dealer HYDRA-MATIC 4L80-E transmission repairs include: Limited on-vehicle serviceable items. Reference Figure 1.

Parts needed to perform limited on-vehicle service on a HYDRA-MATIC 4L80-E transmission are available through your local Parts Distribution Center (PDC).

IMPORTANT

Do not attempt repairs on a 1991 or 1992 HYDRA-MATIC 4L80-E, unless the part is shown in Figure 1 and listed in the repair parts list in this bulletin. All returned HYDRA-MATIC 4L80-E transmissions will be disassembled and inspected in an effort to increase product integrity. Attempting repairs could destroy root cause analysis data.

The Rear Internal Gear Campaign Bulletin 92-C-17 dated July 1992 will not be affected by this bulletin. Continue to implement this campaign. An SRTA should NOT be used to complete this campaign. This is the only exception.

COOLER FLUSHING

Cooler flushing and a flow check MUST be performed whenever a transmission is removed for service. It is essential to flush the cooler prior to a SRTA installation, or when fluid contamination is suspected. Use Kent-Moore tool J35944 and solvent J35944-20 to flush the cooler. Instructions are published in each Service Manual On-vehicle Service Section.

SERVICE PARTS INFORMATION

HYDRA-MATIC 4L80-E/4L80-EHD SRTA Model Replacement Chart

1991 and SRTA 1992 Part # Model Description Models ------- ----- --------------- -------- 8687905 12ABP 4.3L LB4 C&P Truck (91 AB, 92AB) 8687906 12ACP 4.3L LB4 K Truck 4WD (91 AC, 92AC) 8687994 12AHP 4.3L LB4 P Truck Fixed Yoke (92AH) 8687908 12AJP 4.3L LB4 G Van Slip Yoke (91AD, 92AJ) 8687909 12BAP 6.2L LL4, 5.7L L05 C&P (91BA, 91CA, 92BA) 8687910 12BJP 6.2L LL4, 5.7L L05 K Tk. (91BJ, 91CK, 92BJ) 8687911 12BMP 6.2L LL4, 5.7L L05 P 12-15K W/JF9 (91BM, 91CR, 92BM) 8687912 12BNP 5.7L L05 C Truck 12-15K W/JF9 (91BN, 92BN) 8687916 12BSP 6.2L Diesel, 5.7L C&P-96K Conv. (92BS) 8687917 12BUP 6.2L & 5.7L K Truck 4WD-96K Conv. (92BU) 8687918 12BYP 6.2L & 5.7L P Truck 12-15K (92BY) W/JF9-96K Conv. 8687924 12DCP 7.4L L19 C&P Truck 3.42-4.56 Axle (91DC, 92DC) 8687925 12DLP 7.4L L19 K Truck 4WD 4.10-4.56 Axle (91DL, 92DL) 8687926 12DNP 7.4L L19 P Truck 12-15K (91DN, 92DN) 8687927 12DPP 7.4L L19 P Truck 15-16.5K W/JF9 (91DP, 92DP) 8687928 12DRP 7.4L L19 C Truck 12-15K W/JF9 (91DR, 92DR) 8687929 12HTP 7.4L L19 C Truck 4.10 Axle 454SS (91DS, 92HT) 8687932 12LAP 6.5L L65 C&P Truck 3.73-4.56 Axle (92LA) 8687933 12LFP 6.5L L65 K Truck 4WD (92LF) 8687934 12LLP 6.5L L65 C Truck 2WD (92LL) 8687920 12MAP 5.7L L05 G Van Fixed Yoke-96K Conv. (92MA) 8687913 12MBP 5.7L L05 G Van Fixed Yoke (92MB) 8687923 12MHP 7.4L L19 G Van 8.6-1 OK (92MH) 8687921 12MJP 6.2L & 5.7L C&G (10K Slip Yoke-96K (92MJ) Conv. 8687914 12MKP 6.2L & 5.7L C&G (10K Slip Yoke (91BB, 91CB, 92MK) 8687915 12MPP 5.7L C&G Slip Yoke (92ML, 92MP) 8687931 12TSP 7.4L L19 C&G (10K Slip Yoke (91DD, 92TS) 8687930 12TWP 7.4L L19 G Van (92TW)

1991-1992 HYDRA-MATIC 4L80-E/4L80-EHD On-vehicle Serviceable Components:

Part III. Description Number No -----------

*8685042 22 Sensor Asm., A/Trans. Input Spd. & Veh. Spd. 11508805 23 Bolt, Metric Hex (Speed Sensor) 11514343 27 Bolt, Hex Flange (Pan to Case) 8679931 28 Pan, Transmission Oil 8685921 85 Pan Asm., Transmission Oil (Some Models) 8675529 82 Drain Plug Asm., Oil Pan (Some Models) 00116103 83 Washer, Type A Flat Gasket (Some Models) 8677743 29 Seal, Transmission Oil Pan 8654701 30 Magnet, Chip Collector 8678757 31 Filter Asm., Trans. Oil 8656613 32 Seal Assembly, Filter Neck 8686985 34 Pkg.-Electrical Wiring Harness Asm. 8681413 40 Switch Asm., Fluid Pressure 8676222 76 Bolt, Special 8683082 311 2-3 Shift Solenoid & O-Ring Asm. 8683081 313 11-2 Shift Solenoid & O-Ring Asm. 8677314 320 Pressure Control Solenoid 8683188 323 TCC PWM Solenoid

Part numbers are accurate at the time of printing and are subject to change. Refer to the latest GMSPO Parts Catalog for part numbers of SRTA models and service parts.

* Parts are expected to be available on March 22, 1993, all other parts are currently available from GMSPO.

HYDRA-MATIC 4L8O-Et4L80-EHD QUICK CHECK PROCEDURE

1. Write down customer complaint.

2. Check fluid level and condition:

- Burned? Remember brown color of the fluid may be OK. Refer to Service Manual.

- Low or overfilled? Correct as necessary.

3. Use the TECH 1 to check for stored Diagnostic Trouble Codes (DTC).

- Remember, Code 12 tells you that the diagnostic function of PCM is functioning correctly.

- If there is a stored transmission code other than Code 12, refer to Service Manual for diagnostic procedures.

4. Clear codes, test drive truck. Monitor powertrain with a TECH 1. For shift points refer to the shift speed chart.

5. Recheck for stored codes. Correct all codes before continuing.

6. If transmission operates properly-stop.

7. For a harsh or soft shift condition confirm correct cal prom, then perform transmission line pressure check procedure. If line pressure is too high or too low, replace the transmission.

8. For a poor performance condition verify engine performance, then refer to torque converter evaluation in Service Manual.

9. For a vibration or noise condition refer to torque converter vibration test procedure in Service Manual.

10. If all the steps check out ok and the transmission still does not function correctly, refer to Service Manual for diagnosis information. If the diagnosis information determines that an internal component of the transmission needs to be serviced, then replace the transmission. Do not disassemble the transmission. See Page 2 for replacement service part numbers.

HYDRA-MATIC 4L80-E/4L80-EHD TRANSMISSION IDENTIFICATION INFORMATION

Transmission identification information and the SRTA model replacement chart will assist in selecting the correct SRTA unit to order from your local Parts Distribution Center.

SRTA PROCESSING PROCEDURE

Each SRTA unit will be in a container which must be used for core return of the original HYDRA-MATIC 4L80-E assembly. A SRTA Information Packet is included with each SRTA unit. The contents of this envelope are to be removed and used as described with each illustration on the following pages.

SRTA PROCESSING PROCEDURES-INFORMATION PACKET

The contents of this envelope include Limited Warranty Information, Dealer Product Feedback Form, Core Exchange Return Procedure, and a pre-addressed return mailing envelope.

SRTA PROCESSING PROCEDURES-CORE EXCHANGE RETURN

The core return procedure provides detailed instructions for the GM dealer on handling the SRTA and original HYDRA-MATIC 4L80-E units.

SRTA PROCESSING PROCEDURE-FAILURE ANALYSIS INFORMATION

This Product Feedback Form is to be completed by the service manager and/or technician. Fill out these forms as completely as possible to provide information which can be used for analysis. This valuable input can result in future product refinement through corrective action. Insert the white copy of the completed form and a copy of the repair order into the SRTA Information Packet envelope, reseal the envelope and wire tag it to the bell housing of the unit being returned for core exchange. Return the yellow copy of the completed Product Feedback form, using the postage paid envelope, to GM Powertrain Division.

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.