SMU-SEC. 8A-33 & 34 - VEHICLE SPEED, SENSOR, CRUISE CONTROL

SUBJECT: VEHICLE SPEED SENSOR, CRUISE CONTROL ELECTRICAL DIAGNOSIS

MODELS/YEARS: 1993 BRAVADA

The following charts represents new and/or revised information for Section 8A in the 1993 Bravada Service Manual.

DIAGNOSIS - VEHICLE SPEED SENSOR BUFFER

PRELIMINARY CHECKS:

1. Check condition of BRAKE Fuse. if fuse is blown, locate and repair source of overload. Replace fuse.

2. If fuse is not blown, proceed with diagnostics.

SPEED SENSOR COMPONENTS DO NOT OPERATE PROPERLY

TEST RESULT ACTION ---- ------ ------ 1. Place ignition switch in RUN Battery voltage. GO to step 2. position and disconnect Vehicle Speed Sensor Buffer connector C255. Connect voltmeter from PNK/WHT (350) wire at Vehicle Speed Sensor Buffer connector C255 to ground. No voltage. LOCATE and REPAIR open in PNK/WHT (350) wire.

2. Connect voltmeter from PNK/WHT Battery voltage GO to step 3. (350) wire to BLK (150) wire at Vehicle Speed Sensor Buffer connector C255.

No voltage. LOCATE and REPAIR open in BLK (150) wire from Vehicle Speed Sensor Buffer connector C255 to ground terminal G102.

3. Properly support vehicle so A/C voltage reading GO to step 4. drive wheels are off the ground Have engine running and gear selector in DRIVE. Connect A/C voltmeter from PPL/WHT (821) wire to LT GRN/BLK (822) wire at Vehicle Speed Sensor Buffer connector C255.

No voltage. CHECK for open in PPL/WHT (821) and LT GRN/BLK (822) wires. If wires are good, REPLACE speed sensor.

4. Connect Vehicle Speed Sensor D/C Voltage Reading LOCATE and REPAIR Buffer connector C255. Connect open in LT BLU/BLK A/C voltmeter from LT BLU/BLK (824) wire from (824) wire at connector C212 to Vehicle Speed Sensor BLK (150) wire at Vehicle Speed Buffer connector Sensor Buffer connector C255. C255 to I/P cluster. If wire is good, REPLACE instrument cluster.

No voltage. REPLACE Vehicle Speed Sensor Buffer.

CRUISE CONTROL DOES NOT OPERATE PROPERLY

TEST RESULT ACTION ---- ------ ------ 1. Place ignition switch in RUN Battery voltage. GO to step 2. position and disconnect Vehicle Speed Sensor Buffer connector C255. Connect voltmeter from PNK/WHT (350) wire at Vehicle Speed Sensor Buffer connector C255 to ground.

No Voltage. LOCATE and REPAIR open in PNK/WHT (350) wire.

2. Connect voltmeter form PNK/WHT Battery voltage. GO to step 3. (350) wire to BLK (150) wire at Vehicle Speed Sensor Buffer No Voltage. LOCATE and REPAIR connector C255. open in BLK (150) wire from Vehicle Speed Sensor Buffer connector C255 to ground G102.

3. Properly support vehicle so drive A/C voltage reading. GO to step 4. wheels are off the ground. Have engine running and gear selector in DRIVE. Connect A/C voltmeter No voltage. CHECK for open in from PPL/WHT (821) wire to LT PPL/WHT (821) and GRN/BLK (822) wire at Vehicle LT GRN/BLK (822) Speed Sensor Buffer connector wires. If wires C255. are good, REPLACE speed sensor.

4. Connect Vehicle Speed Sensor D/C voltage reading. LOCATE and REPAIR Buffer connector C255. Connect open in YEL (400) A/C voltmeter from YEL (400) wire wire from Vehicle at Vehicle Speed Sensor Buffer Speed Sensor Buffer connector C249 to BLK (150) wire connector C249 to at Vehicle Speed Sensor Buffer cruise control connector C255. module connector C250.

No voltage. REPLACE Vehicle Speed Sensor Buffer

DIAGNOSIS - CRUISE CONTROL

PRELIMINARY CHECKS:

1. Check condition of IGN/GAU Fuse. If fuse is blown, locate and repair source of overload and replace fuse.

2. If fuse is not blown, proceed with diagnostics.

CRUISE CONTROL DOES NOT OPERATE

TEST RESULT ACTION

1. Place ignition switch in RUN and Battery voltage GO to step 2. cruise control switch in ON. Connect digital voltmeter from No Voltage LOCATE and REPAIR PNK/BLK (139) wire at cruise open in PNK/BLK control switch connector C251 to (139) wire from ground. cruise control switch connector C251 to fuse block connector C232.

2. Connect digital voltmeter from GRA Battery voltage GO to step 3. (397) wire at cruise control switch connector C251 to ground. No voltage. REPLACE cruise control switch.

3. Connect digital voltmeter from GRA Battery voltage GO to step 4. (397) wire at brake switch connector C252 to ground. No Voltage. CHECK connection at brake switch connector C252.

4. Connect digital voltmeter from GRA Battery voltage GO to step 5. (397) wire at cruise control module connector C250 to ground. No Voltage. LOCATE and REPAIR open in GRA (397) wire from cruise control module connector C250 to cruise control switch connector C251.

5. Connect digital voltmeter from GRA Battery voltage GO to step 6. (397) wire to BLK (150) wire at cruise control module connector No Voltage. LOCATE and REPAIR C250. open in BLK (150) wire from cruise control module connector C250 to cruise control switch connector C251.

6. Connect digital voltmeter from Battery voltage GO to step 7. GRA/BLK (87) wire at brake switch connector C252 to ground. No voltage CHECK adjustment of brake switch. If properly adjusted, REPLACE brake switch.

7. Connect digital voltmeter from Battery voltage Go to step 9. GRA/BLK (87) wire ate cruise control module connector C250 to ground. No voltage. LOCATE and REPAIR open in GRA/BLK wire from cruise control module connector C250 to brake switch connector C252.

8. Connect digital voltmeter from DK Battery voltage REPLACE cruise BLU (84) wire at cruise control control switch. switch connector C251 to ground. No voltage. GO to step 10.

9. Connect digital voltmeter from DK Battery voltage. GO to step 11. BLU (84) wire at cruise control switch connector C251 to ground. No voltage. REPLACE cruise Depress and hold SET switch. control switch.

10. Connect digital voltmeter from DK Battery voltage GO to step 12. BLU (84) wire at cruise control module connector C250 to ground. No Voltage. LOCATE and REPAIR Depress and hold SET switch. open in DK BLU (84) wire from cruise control module connector C250 to cruise control switch connector C251.

11. Connect digital voltmeter from DK Battery voltage GO to step 13. GRN (83) wire at cruise control switch connector C251 to ground. No Voltage. REPLACE cruise Depress and hold RES/ACCL switch control switch.

12. Connect digital voltmeter from DK Battery voltage GO to step 14. GRN (83) wire at cruise control module connector C250 to ground. No voltage. LOCATE and REPAIR Depress and hold RES/ACCL switch. open in DK GRN (83) wire from cruise control module connector C250 to cruise control switch connector C251.

13. Disconnect cruise control module A reading of 30 to GO to step 17. connector C250. Connect digital 55 ohms. ohmmeter from DK BLU/WHT (43) wire to BLK (150) wire at cruise A reading greater GO to step 15. control module connector C250. than 55 ohms.

A reading less than GO to step 16. 30 ohms.

14. Disconnect cruise control servo A reading greater REPLACE cruise connector C153. Connect digital than 55 ohms. control servo. ohmmeter from 403 terminal to 150 terminal at cruise control servo. A reading less than LOCATE and 55 ohms. REPAIR open in DK BLU/WHT (403) wire from cruise control servo connector C153 to cruise control module connector C250.

15. Disconnect cruise control servo A reading less REPLACE control connector C153. Connect digital than 30 ohms. servo. ohmmeter from 403 terminal to 150 terminal at control servo. A reading greater LOCATE and than 30 ohms. REPAIR short in DK BLU/WHT (403) wire from cruise control servo connector C153 to cruise control module connector C250.

16. Connect digital ohmeter from LT A reading of 30 to GO to step 19. GRN (402) wire to BLK (150) wire 55 ohms. at cruise control module connector C250. A reading greater GO to step 17. than 55 ohms.

A reading less than GO to step 18. 30 ohms.

17. Disconnect cruise control servo A reading greater REPLACE cruise connector C153. Connect digital than 55 ohms. control servo. ohmmeter from 402 terminal to 150 terminal at control servo. A reading less than LOCATE and 55 ohms. REPAIR open in LT GRN (402) wire from cruise control servo connector C153 to cruise control module connector C250.

18. Disconnect cruise control servo A reading less than REPLACE control connector C153. Connect digital 30 ohms. servo. ohmmeter from 402 terminal to 150 terminal at control servo. A reading greater LOCATE and than 30 ohms. REPAIR short in LT GRN (402) wire from cruise control servo connector C153. to cruise control module connector C250.

19. Connect digital ohmmeter from LT A reading of 15 to GO to step 23. BLU/BLK (399) wire to TAN (398) 25 ohms. wire at cruise control module connector C250. A reading greater GO to step 21. than 25 ohms.

A reading less than GO to step 22. 25 ohms.

20. Disconnect cruise control servo A reading greater REPLACE servo. connector C153. Connect digital than 25 ohms. ohmmeter from 398 terminal to 399 terminal at control servo. A reading less than LOCATE and 25 ohms. REPAIR open in LT BLU/BLK (399) wire and TAN (398) wire from cruise control servo connector C153 to cruise control module connector C250.

21. Disconnect cruise control servo A reading greater REPLACE control connector C153. Connect digital than 15 ohms. servo. ohmmeter from TAN (398) wire to BLK (150) wire at cruise control A reading less than LOCATE and module connector C250. 15 ohms. REPAIR short in TAN (398) wire from cruise control servo connector C153 to cruise control module connector C250.

22. Properly support vehicle so drive D/C voltage reading CHECK for vacuum wheels are off the ground. Have problem. Refer engine running and gear selector in to Section 9B in DRIVE. With the cruise switch in this Manual. the ON position, connect A/C voltmeter from GRA (397) wire to No voltage. REFER to "CRUISE YEL (400) wire at cruise control CONTROL DOES NOT module connector C250. OPERATE PROPERLY" chart in the Vehicle Speed Sensor section.

CRUISE CONTROL DOES NOT DISENGAGE WHEN BRAKE PEDAL IS DEPRESSED

1. Place ignition switch in RUN Test lamp lights. REPLACE control position and cruise control module. switch in ON. Depress brake pedal Connect test lamp from GRA/BLK (87) Test lamp does CHECK adjustment wire at brake switch connector not light. of brake switch. C252 to ground. If adjustment cannot be cor- rected, REPLACE brake switch. GO to step 2.

2. Connect digital voltmeter from GRA Battery voltage. GO to step 3. (397) wire at brake switch connector C252 to ground. No voltage. CHECK connection at brake switch connector C252.

3. Connect digital voltmeter from GRA Battery voltage. GO to step 4. (397) wire at cruise control module connector C250 to ground. No voltage. LOCATE and REPAIR open in GRA (397) wire from cruise control module connector C250 to cruise control switch connector C251.

4. Connect digital voltmeter from GRA Battery voltage. GO to step 5. (397) wire to BLK (150) wire at cruise control module connector No voltage. LOCATE and REPAIR C250. open in BLK (150) wire from cruise control module connector C250 to bus bar ground connector C228.

5. Connect digital voltmeter from Battery voltage. GO to step 6. GRA/BLK (87) wire at brake switch, connector C252 to ground. No voltage. CHECK adjustment of brake switch. If properly ad- justed, REPLACE brake switch.

6. Connect digital voltmeter from Battery voltage. REPLACE cruise GRA/BLK (87) wire at cruise control control module. module connector C250 to ground. No voltage. LOCATE and REPAIR open in GRA/BLK (87) wire from cruise control module connector C250 to brake switch connector C252.

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.