Home/Chevrolet/Cutaway P30/Chevrolet Cutaway P30 (1988-1999)/Repair manual/Engine Controls - Tests W/codes - Transmission/CODE 85, UNDEFINED GEAR RATIO

Contents

Section: Engine Controls - Tests W/codes - Transmission

INTRODUCTION

SELF-DIAGNOSTIC SYSTEM

Preliminary Inspection

Diagnostic Procedure

ENTERING & EXITING DIAGNOSTIC MODE

TROUBLE CODE IDENTIFICATION

CLEARING TROUBLE CODES

PCM/TCM LOCATION

SPECIAL TOOLS (DIAGNOSTIC)

TEST EQUIPMENT

TROUBLE CODE CHARTS

CODE 28, FLUID PRESSURE SWITCH ASSEMBLY FAULT

Diagnostic Aids

CODE 37, BRAKE SWITCH STUCK ON

CODE 38, BRAKE SWITCH STUCK OFF

CODE 52, LONG SYSTEM VOLTAGE HIGH

CODE 53, SYSTEM VOLTAGE HIGH

CODE 58, TRANS FLUID TEMP. SENS CKT (HIGH TEMP. INDICATED)

CODE 59, TRANSMISSION FLUID TEMP. SENSOR CIRCUIT (LOW TEMP. INDICATED)

CODE 66, 3-2 CONTROL SOLENOID CIRCUIT FAULT

CODE 67, TCC SOLENOID CIRCUIT CHECK

CODE 69, TORQUE CONVERTER CLUTCH STUCK ON

2WD & AWD

4WD

CODE 73, PRESSURE CONTROL SOLENOID (CURRENT ERROR)

CODE 75, SYSTEM VOLTAGE LOW

CODE 79, TRANSMISSION FLUID OVERTEMP

CODE 81, 2-3 SHIFT SOLENOID CIRCUIT FAULT

CODE 82, 1-2 SHIFT SOLENOID CIRCUIT FAULT

VEHICLE SPEED SENSOR CHECK (2WD & AWD)

VEHICLE SPEED SENSOR CHECK (4WD)

BRAKE SIGNAL CIRCUIT CHECK

TORQUE CONVERTER CLUTCH (TCC) SOLENOID CIRCUIT CHECK

3-2 CONTROL SOLENOID CIRCUIT CHECK

1-2 SHIFT SOLENOID CIRCUIT CHECK

2-3 SHIFT SOLENOID CIRCUIT CHECK

PRESSURE CONTROL SOLENOID CIRCUIT CHECK

FLUID PRESSURE SWITCH ASSEMBLY CIRCUIT CHECK

CODE 28, PRESSURE SWITCH MANIFOLD FAULT

CODE 39, TORQUE CONVERTER CLUTCH STUCK OFF

NOTES ON INTERMITTENTS

CODE 68, OVERDRIVE RATIO ERROR

CODE 73, FORCE MOTOR CURRENT (CURRENT ERROR)

NOTE ON INTERMITTENTS

CODE 81, SOLENOID "B" CIRCUIT FAULT

CODE 82, SOLENOID "A" CIRCUIT FAULT

CODE 83, TCC SOLENOID CIRCUIT FAULT

CODE 85, UNDEFINED GEAR RATIO

CODE 86, LOW GEAR RATIO

CODE 87, HIGH GEAR RATIO

VEHICLE SPEED SENSOR CHECK

INPUT SPEED SENSOR CIRCUIT CHECK

PRESSURE SWITCH MANIFOLD CIRCUIT CHECK

TORQUE CONVERTER CLUTCH (TCC) CIRCUIT CHECK

SHIFT SOLENOID "A" CIRCUIT CHECK

SHIFT SOLENOID "B" CIRCUIT CHECK

FORCE MOTOR CIRCUIT CHECK

All sections

CODE 85, UNDEFINED GEAR RATIO Chevrolet Cutaway P30

Engine Controls - Tests W/codes - Transmission 2 illustrations ~160 words

CODE 85, UNDEFINED GEAR RATIO

While in each gear, PCM/TCM calculates actual gear ratio from input and output speed readings, also referred to as vehicle speed, then compares these to what gear ratio should be, taking into consideration selected gear range. This monitor includes reverse gear, but does not include overdrive gear.

Scheme 197

Scheme 197: CODE 85, UNDEFINED GEAR RATIO

Scheme 197: CODE 85, UNDEFINED GEAR RATIO

Note. Test numbers refer to numbers on diagnostic chart.

This test verifies the proper function of the input sensor.
This test verifies the proper function of the output sensor (vehicle speed sensor).

The PCM/TCM relies on Vehicle Speed Sensor Buffer Module (DRAC) to indicate what gear range has been selected. DRAC must be functioning properly or Code 85 may be set. Check all connections, especially those at the transmission pass-thru connector. If code is intermittent, see INTERMITTENTS in TESTS W/O CODES article in this section. Compare scan tester gear ratio reading to specifications in GEAR RATIO table.

Scheme 198

Scheme 198

Scheme 198

Gear	Less Than	More Than
1st	12.38	22.63
2nd	11.43	21.58
3rd	1.95	21.05
Reverse	11.97	22.17

GEAR RATIO