ALLISON Transmission B 500 Full Service Repair Manual

TS2470EN Printed in the U.S.A. Copyright © 1998 General Motors Corp. Troubleshooting Manual Division of General Motors Corporation P.O. Box 894 Indianapolis, Indiana 46206-0894 May 1998 Revision 1, 199910 Allison Transmission MD/HD/B Series Transmissions WTEC II Controls (Pre-TransID and TID 1) MD 3060/MD 3066/MD 3560(P)(R) MD 3070PT HD 4060/HD 4560(P)(R) B 300/B 400/ B 500(P)(R)

WTEC II ELECTRONIC CONTROLS TROUBLESHOOTING MANUAL ii Copyright © 1998 General Motors Corp. This manual provides troubleshooting information for Allison Transmission Division, MD/HD/B Series Transmissions. Service Manuals SM2148EN and SM2457EN, and Parts Catalogs PC2150EN and PC2456EN may be used in conjunction with this manual. This manual includes: • Description of the WTEC II electronic control system. • Description of the electronic control system components. • Description of diagnostic codes, system responses to faults, and troubleshooting. • Wire, terminal, and connector repair information. Specific instructions for using many of the available or required service tools and equipment are not included in this manual. The service tool manufacturer will furnish instructions for using the tools or equipment. Additional information may be published from time to time in Service Information Letters (SIL) and will be included in future revisions of this and other manuals. Please use these SILs to obtain up-to-date information concerning Allison Transmission products. This publication is revised periodically to include improvements, new models, special tools, and procedures. A revision is indicated by a letter suffix added to the publication number. Check with your Allison Transmission service outlet for the currently applicable publication. Additional copies of this publication may be purchased from authorized Allison Transmission service outlets. Look in your telephone directory under the heading of Transmissions — Truck, Tractor, etc. Take time to review the Table of Contents and the manual. Reviewing the Table of Contents will aid you in quickly locating information. NOTE: Allison Transmission is providing for service of WTEC II wiring harnesses and wiring harness components as follows: (See Service Information Letter 1-WT-97 for further information.) • Repair parts for the internal wiring harness and for wiring harness components attached to the shift selector will be available through the Allison Transmission Parts Distribution Center (PDC). Use the P/N from your appropriate parts catalog or from Appendix E in this manual. Allison Transmission is responsible for warranty on these parts. • Since January, 1998, all WTEC II external harnesses and external harness components must be obtained from St. Clair Technologies Inc. (SCTI). SCTI provides parts to any Allison customer or OEM and is responsible for warranty on these parts. SCTI recognizes ATD, manufacturers, and SCTI part numbers. SCTI provides a technical HELPLINE at 519-627-1673 (Wallaceburg). SCTI has parts catalogs available. The SCTI addresses and phone numbers for parts outlets are: St. Clair Technologies, Inc. 1050 Old Glass Road Wallaceburg, Ontario, Canada, N8A 3T2 Phone: (519) 627-1673 Fax: (519) 627-4227 St. Clair Technologies, Inc. 1111 Mikesell Street Charlotte, Michigan 48813 Phone: (517) 541-8166 Fax: (517) 541-8167 St. Clair Technologies, Inc. c/o Mequilas Tetakawi Carr. Internationale KM 1969 Guadalajara – Nogales, KM2 Empalme, Sonora, Mexico Phone: 011-52-622-34661 Fax: 011-52-622-34662 FOREWORD — How to Use This Manual

Copyright © 1998 General Motors Corp. iii WTEC III ELECTRONIC CONTROLS TROUBLESHOOTING MANUAL IMPORTANT SAFETY NOTICE IT IS YOUR RESPONSIBILITY to be completely familiar with the warnings and cautions used in this manual. These warnings and cautions advise against using specific service procedures that can result in personal injury, equipment damage, or cause the equipment to become unsafe. These warnings and cautions are not exhaustive. Allison Transmission could not possibly know, evaluate, or advise the service trade of all conceivable procedures by which service might be performed or of the possible hazardous consequences of each procedure. Consequently, Allison Transmission has not undertaken any such broad evaluation. Accordingly, ANYONE WHO USES A SERVICE PROCEDURE OR TOOL WHICH IS NOT RECOMMENDED BY ALLISON TRANSMISSION MUST first be thoroughly satisfied that neither personal safety nor equipment safety will be jeopardized by the service procedures used. Also, be sure to review and observe WARNINGS, CAUTIONS, and NOTES provided by the vehicle manufacturer and/or body builder before servicing the Allison transmission in that vehicle. Proper service and repair is important to the safe and reliable operation of the equipment. The service procedures recommended by Allison Transmission and described in this manual are effective methods for performing troubleshooting operations. Some procedures require using specially designed tools. Use special tools when and in the manner recommended. WARNINGS, CAUTIONS, AND NOTES Three types of headings are used in this manual to attract your attention: NOTE: Is used when an operating procedure, practice, etc., is essential to highlight. WARNING! Is used when an operating procedure, practice, etc., which, if not correctly followed, could result in injury or loss of life. CAUTION: Is used when an operating procedure, practice, etc., which, if not strictly observed, could result in damage to or destruction of equipment. The WARNINGS, CAUTIONS, and NOTES in this manual apply only to the Allison transmission and not to other vehicle systems which may interact with the transmission. Be sure to review and observe any vehicle system information provided by the vehicle manufacturer and/or body builder at all times the Allison transmission is being serviced.

WTEC II ELECTRONIC CONTROLS TROUBLESHOOTING MANUAL iv Copyright © 1998 General Motors Corp. TRADEMARKS USED IN THIS MANUAL The following trademarks are the property of the companies indicated: • LPS ® Cleaner is a registered trademark of LPS Laboratories. • VCI #10 ® is the registered trademark for a vapor phase rust preventive manufactured by Daubert Chemical Company, Chicago, Illinois. VCI #10 is covered by Military Specifications MIL-L-46002 (ORD) and MIL-I-23310 (WEP) under the designation of Nucle Oil. • Biobor JF ® is the registered trademark for a biological inhibitor manufactured by Hammonds Fuel Additives Corporation. • Loctite ® is a registered trademark of the Loctite Corporation. • Teflon ® is a registered trademark of the DuPont Corporation. • Pro-Link ® is a registered trademark of MicroProcessor Systems, Inc. SHIFT SELECTOR TERMS AND DISPLAY INDICATIONS Shift selector terms and displays are represented in this manual as follows: • Button Names — ⇑ ⇓, DISPLAY MODE, MONITOR, SELECT, etc. • Transmission Ranges — D (Drive), N (Neutral), 1 (First), R (Reverse), etc. • Displays — “OL”, “OK”, etc.

Copyright © 1998 General Motors Corp. v Page Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i SAFETY INFORMATION Important Safety Notice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii Warnings, Cautions, and Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii Trademarks Used in This Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv Shift Selector Terms and Display Indications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv SECTION 1. GENERAL DESCRIPTION 1–1. TRANSMISSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–1 1–2. ELECTRONIC CONTROL UNIT (ECU) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–3 1–3. SHIFT SELECTOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–3 A. Pushbutton Shift Selector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–3 B. Lever Shift Selector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–4 1–4. THROTTLE POSITION SENSOR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–4 1–5. SPEED SENSORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–5 1–6. CONTROL MODULE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–6 1–7. WIRING HARNESSES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–7 A. External Wiring Harness. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–7 B. Internal Wiring Harness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–8 1–8. VEHICLE INTERFACE MODULE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–10 1-9. TRANSID FEATURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10 SECTION 2. DEFINITIONS AND ABBREVIATIONS 2–1. DO NOT SHIFT LIGHT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–1 2–2. DIAGNOSTIC DATA READER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–1 2–3. ABBREVIATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–2 SECTION 3. BASIC KNOWLEDGE 3–1. BASIC KNOWLEDGE REQUIRED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3–1 3–2. USING THE TROUBLESHOOTING MANUAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3–1 3–3. SYSTEM OVERVIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3–2 3–4. IMPORTANT INFORMATION IN THE TROUBLESHOOTING PROCESS . . . . . . . . . . . . . . . 3–2 3–5. BEGINNING THE TROUBLESHOOTING PROCESS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3–3 SECTION 4. WIRE CHECK PROCEDURES 4–1. CHECKING OPENS, SHORTS BETWEEN WIRES, AND SHORTS-TO-GROUND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4–1 4–2. CHECKING AT TRANSMISSION CONNECTOR AND THE INTERNAL HARNESS FOR OPENS, SHORTS BETWEEN WIRES, AND SHORTS-TO-GROUND . . . . . . . . . . . . . . . 4–2 TABLE OF CONTENTS WTEC II ELECTRONIC CONTROLS TROUBLESHOOTING MANUAL

vi Copyright © 1998 General Motors Corp. SECTION 5. OIL LEVEL SENSOR Page 5–1. ELECTRONIC FLUID LEVEL CHECK (SHIFT SELECTOR) . . . . . . . . . . . . . . . . . . . . . . . . . 5–1 A. Fluid Level Check Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5–1 5–2. ELECTRONIC FLUID LEVEL CHECK (PRO-LINK ® 9000) . . . . . . . . . . . . . . . . . . . . . . . . . . . 5–4 A. Fluid Level Check Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5–4 SECTION 6. DIAGNOSTIC CODES 6–1. DIAGNOSTIC CODE MEMORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6–1 6–2. CODE READING AND CODE CLEARING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6–1 6–3. DIAGNOSTIC CODE RESPONSE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6–3 6–4. SHIFT SELECTOR DISPLAYS RELATED TO ACTIVE CODES . . . . . . . . . . . . . . . . . . . . . . . 6–3 6–5. DIAGNOSTIC CODE LIST AND DESCRIPTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6–4 6–6. DIAGNOSTIC CODE TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6–17 A. Beginning the Troubleshooting Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6–17 B. Solenoid Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6–17 C. Diagnostic Code Schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6–18 D. Diagnostic Code 13 and 35 Schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6–18 SECTION 7. INPUT AND OUTPUT FUNCTIONS 7–1. INPUT FUNCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7–1 7–2. OUTPUT FUNCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7–3 SECTION 8. GENERAL TROUBLESHOOTING OF PERFORMANCE COMPLAINTS 8–1. GENERAL NOTES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8–1 8–2. TROUBLESHOOTING PERFORMANCE COMPLAINTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8–2 APPENDICES A. IDENTIFICATION OF POTENTIAL CIRCUIT PROBLEMS . . . . . . . . . . . . . . . . . . . . . . . . . . . A–1 B. CHECKING CLUTCH PRESSURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B–1 C. SOLENOID AND CLUTCH CHART . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C–1 D. WIRE/CONNECTOR CHART. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D–1 E. CONNECTOR PART NUMBERS, TERMINAL PART NUMBERS, TOOL PART NUMBERS, AND REPAIR INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . E–1 F. THROTTLE POSITION SENSOR ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F–1 G. MISCELLANEOUS ITEMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G–1 H. HYDRAULIC SCHEMATICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . H–1 J. WT WIRING SCHEMATICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . J–1 K. SOLENOID AND TEMPERATURE CHARTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . K–1 L. EXTERNALLY-GENERATED ELECTRONIC INTERFERENCE . . . . . . . . . . . . . . . . . . . . . . . L–1 M. DIAGNOSTIC TREE — WT SERIES HYDRAULIC SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . M–1 N. PRO-LINK ® 9000 DIAGNOSTIC DATA READER INFORMATION . . . . . . . . . . . . . . . . . . . . . N–1 P. INPUT/OUTPUT FUNCTION WIRING SCHEMATICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P–1 TABLE OF CONTENTS ( C o n t ' d) WTEC II ELECTRONIC CONTROLS TROUBLESHOOTING MANUAL

Copyright © 1998 General Motors Corp. 1–1 WTEC II ELECTRONIC CONTROLS TROUBLESHOOTING MANUAL 1–1. TRANSMISSION The World Transmission Electronic Controls WTEC II system features closed-loop clutch control to provide superior shift quality over a wide range of operating conditions. MD 3000 (except 3070), HD 4000, and B Series configurations can be programmed to have up to six forward ranges, neutral, and one reverse range. The MD 3070 has seven forward ranges and one reverse range. Figures 1–1 and 1–2 show electronic control unit components. WTEC II Electronic Controls consist of the following components: • Basic or Max Feature Electronic Control Unit (ECU) • Pushbutton or Lever Shift Selectors (remote or integral to the ECU) • Optional Secondary Shift Selector • Engine, Turbine and Output Speed Sensors • Throttle Position Sensor (TPS) (or electronic engine throttle signal or PWM signal) • Control Module (Electro-Hydraulic Valve Body) • Wiring Harnesses • Vehicle Interface Module (VIM) • Optional Retarder Controls • TransID Feature NOTE: Model Year ’94 and earlier WT Series Electronic Controls operate on 12VDC. Vehicles with a 24VDC system require a voltage equalizer or converter to supply 12V to the electronic control system. Model Year ’95 and later transmissions operating on 24VDC require a 24V VIM and a 24V wiring harness which includes shielding for the turbine and output speed sensors. Figure 1–1. WTEC II Electronic Control Components (Units Produced Before 9/94) 7 8 9 4 5 6 1 2 3 0 ENTER = x – + – OPTIONAL DEUTSCH DDR CONNECTOR INTEGRAL ECU/ SHIFT SELECTORS REMOTE ECU RETARDER MODULATION REQUEST (RMR) SENSOR CONNECTOR ELECTRONIC CONTROL UNIT (ECU) CONNECTORS DIAGNOSTIC DATA READER (DDR) CONNECTOR PRO-LINK ® DIAGNOSTIC TOOL J 38538-A THROTTLE POSITION SENSOR VEHICLE INTERFACE MODULE (VIM) MD/B 300/B 400 RETARDER CONNECTOR (INCLUDES OUTPUT SPEED SENSOR) MD 3070 TRANSFER CASE CONNECTOR OUTPUT SPEED SENSOR *CONNECTOR TRANSMISSION CONNECTOR ENGINE SPEED SENSOR CONNECTOR V01634 TPS CONNECTOR TURBINE SPEED SENSOR CONNECTOR (HD/B 500) HD/B 500 RETARDER TEMPERATURE SENSOR CONNECTOR REMOTE SERIAL INTERFACE CONNECTOR REMOTE PUSHBUTTON SHIFT SELECTOR STRIP PUSHBUTTON SHIFT SELECTOR REMOTE LEVER SHIFT SELECTOR RETARDER “K” CONNECTOR (HD/B 500) HD/MD/B RETARDER ACCUMULATOR “H” SOLENOID CONNECTOR OPTIONAL BULKHEAD CONNECTOR WIRING HARNESS NOTE: Illustration is not to scale. *All HD/B 500 models All Non-Retarder MD/B 300/B 400 models 1 2 D N R D N R VEHICLE INTERFACE WIRING (VIW) CONNECTOR SECTION 1 — GENERAL DESCRIPTION

WTEC II ELECTRONIC CONTROLS TROUBLESHOOTING MANUAL 1–2 Copyright © 1998 General Motors Corp. GENERAL DESCRIPTION Figure 1–2. WT Electronic Control Unit Components (Units Produced 9/94–12/97) Figure 1–3 is a block diagram of the basic system’s inputs and outputs. Figure 1–3. Electronic Control Unit Block Diagram 7 8 9 4 5 6 1 2 3 0 ENTER = x – + – OPTIONAL DEUTSCH DDR CONNECTOR INTEGRAL ECU/ SHIFT SELECTORS REMOTE ECU PRO-LINK ® DIAGNOSTIC TOOL J 38538-A THROTTLE POSITION SENSOR MD/B 300/B 400 RETARDER CONNECTOR (INCLUDES OUTPUT SPEED SENSOR) MD 3070 TRANSFER CASE CONNECTOR OUTPUT SPEED SENSOR *CONNECTOR TRANSMISSION CONNECTOR ENGINE SPEED SENSOR CONNECTOR V01587 TPS CONNECTOR TURBINE SPEED SENSOR CONNECTOR (HD/B 500) HD/B 500 RETARDER TEMPERATURE SENSOR CONNECTOR REMOTE SERIAL INTERFACE CONNECTOR RETARDER “K” CONNECTOR (HD/B 500) HD/MD/B RETARDER ACCUMULATOR “H” SOLENOID CONNECTOR OPTIONAL BULKHEAD CONNECTOR WIRING HARNESS NOTE: Illustration is not to scale. *All HD/B 500 models All Non-Retarder MD/B 300/B 400 models 1 2 D N R D N R ELECTRONIC CONTROL UNIT (ECU) CONNECTORS DIAGNOSTIC DATA READER (DDR) CONNECTOR VEHICLE INTERFACE MODULE (VIM) VEHICLE INTERFACE WIRING (VIW) CONNECTOR RETARDER MODULATION REQUEST (RMR) SENSOR CONNECTOR REMOTE PUSHBUTTON SHIFT SELECTOR STRIP PUSHBUTTON SHIFT SELECTOR REMOTE LEVER SHIFT SELECTOR SHIFT SELECTOR RANGE AND MODE SWITCH TONE/DISPLAY VIM INPUTS OUTPUTS ECU SPEED SENSORS THROTTLE POSITION SENSOR RETARDER MODULATION V01812 TEMPERATURE SENSOR (SUMP/RETARDER) SOLENOIDS OIL LEVEL SENSOR C3 PRESSURE SWITCH

Copyright © 1998 General Motors Corp. 1–3 GENERAL DESCRIPTION WTEC II ELECTRONIC CONTROLS TROUBLESHOOTING MANUAL 1–2. ELECTRONIC CONTROL UNIT (ECU) The ECU (Figure 1–4) contains the microcomputer which is the brain of the control system. The ECU receives and processes information defining: shift selector position, throttle position, sump/retarder temperature, engine speed, turbine speed, and transmission output speed. The ECU uses the information to control transmission solenoids and valves, supply system status, and provide diagnostic information. The ECU contains an Electronically Erasable Programmable Read Only Memory (EEPROM) which is programmed with the shift calibration and other data for a specific transmission assembly, engine, and vehicle vocation. Figure 1–4. Electronic Control Unit (ECU) 1–3. SHIFT SELECTOR Pushbutton and lever shift selectors are available for the WT Series. Either shift selector may be ordered attached to (integral with), or remote from, the ECU. Both shift selectors are equipped with a digital display. However, the strip pushbutton shift selector does not have a digital display. On the shift selectors, between the range selected and the range monitored (attained) digits, is a MODE ON indicator position. During normal transmission operation MODE ON indicates that a secondary or special operating condition has been selected by pressing the MODE button. In diagnostic display mode, MODE ON indicates the displayed diagnostic code is active. There is a SERVICE indicator icon under the MODE ON indicator. It is illuminated when codes 21 XX, 63 00, and 66 00 are active (for ECUs programmed after 9/26/94). When a transmission fault occurs that causes the DO NOT SHIFT light to turn on, the shift selector sounds a tone to indicate transmission shifting is restricted. A. Pushbutton Shift Selector (Figure 1–5) The full-function pushbutton shift selector has six (6) buttons and a digital display. The six buttons are: R (Reverse), N (Neutral), D (Drive), ⇑ (Up), ⇓ (Down), and MODE. Manual forward range downshifts; upshifts are made by pressing the ⇑ (Up) or ⇓ (Down) arrow buttons after selecting D (Drive). The N (Neutral) button has a raised lip to aid in finding it by touch. The digital display on the pushbutton selector indicates the range selected on the left side and the range monitored (attained) on the right side. The MODE button is pressed to select a secondary or special operating condition, such as ECONOMY shift schedule. The vehicle dimmer-control changes display brightness. Diagnostic information is obtained by pressing the ⇑ (Up) and ⇓ (Down) arrow buttons at the same time. V00626.01 ECU

WTEC II ELECTRONIC CONTROLS TROUBLESHOOTING MANUAL 1–4 Copyright © 1998 General Motors Corp. GENERAL DESCRIPTION A strip pushbutton shift selector does not have a MODE button, SERVICE icon, or diagnostic display capability. The Pro-Link ® 9000 or a customer-furnished remote display must be used for diagnostic purposes. Figure 1–5. Pushbutton Shift Selectors B. Lever Shift Selector (Figure 1–6) The lever shift selector can only be ordered with as many as six forward range positions (seven for the MD 3070), as well as R (Reverse) and N (Neutral). The shift hold mechanism is released by pressing a button on the side of the shift handle. The range selector lever can be moved freely between numbered forward ranges. Press and hold the shift hold button to move into or out of the D (Drive) position or when moving into or out of N (Neutral) or R (Reverse). The digital display on the lever selector indicates the selected range at the top and the range monitored (attained) at the bottom. A MODE button and a recessed DISPLAY MODE button are also on the face of the lever shift selector. The MODE button is pressed to select a secondary or special operating condition, such as ECONOMY shift schedule. Diagnostic information is obtained by pressing the DISPLAY MODE button. The vehicle dimmer-control changes display brightness. Figure 1–6. Six-Speed And Seven-Speed Lever Shift Selectors R N D MODE MODE ON SERVICE SELECT POSITION 1 2 D N R 1 2 D N R 2 1 3 D N R D N R 1 D N R 2 1 3 D N R V01588 MODE ID PUSHBUTTON SELECTOR STRIP PUSHBUTTON SHIFT SELECTORS SELECT MONITOR MODE ON MODE 1 2 3 4 5 D N R SELECT MONITOR MODE ON SERVICE SERVICE MODE 1 2 3 4 5 6 D N R V01589 SIX-SPEED LEVER SELECTOR DISPLAY MODE BUTTON MODE ID HOLD OVERRIDE BUTTON SEVEN-SPEED LEVER SELECTOR

ALLISON Transmission B 500 Full Service Repair Manual

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