Document ID: 1379942 https://gsi.ext.gm.com/gsi/showdoc.do?laboropcode=&docsyskey=1379942&cellid=29035&pu... Page 1 of 1 1995 GMC Truck Sonoma Pickup - 2WD Blazer, Bravada, Jimmy, S10 Pickup, Sonoma VIN S/T Service Manual Engine Engine Controls - 4.3L Repair Instructions Document ID: 1379942 Vehicle Control Module General Description The VCM is located on the right hand side fenderwell. The VCM is the control center for the fuel emissions automatic transmission control functions and the antilock brakes systems. The VCM constantly monitors the information from the various sensors. The VCM controls the component systems which affect the engine, the transmission, and the antilock operation. The VCM alerts the driver through the Malfunction Indicator Lamp (MIL) or the antilock indicator lamp. The VCM stores the DTCs which identify the problem areas for the technician making repairs. Refer to Vehicle Control Module (Serial Data Communication), for further information on using the diagnostic function of the VCM for engine operation. Refer to Transmission for the diagnosis of the automatic transmission. Refer to Section 5E3B in the appropriate service manual for further information on the antilock brakes. The VCM in this vehicle is programmable. The only services allowed on the VCM is the control module replacement with the KS calibrator PROM transferred or the KS calibrator PROM only. The KS calibrator contains the up integrated knock sensor calibration. The VCM stores the 4 calibrations in the Electronically Erasable Programmable Read Only Memory (EEPROM). When replacing the VCM, programming the EEPROM and transferring the KS calibrator PROM to the new VCM is mandatory. Refer to the EEPROM Programming. The 4 calibrations required for the VCM are the Powertrain, the BS, the VSS buffer, and the /C. Each calibration has its own part number. Determine the correct calibrations for a particular vehicle based on the VIN number of the vehicle. Vehicle Control Module (VCM) The VCM processes the various input information. The VCM sends the necessary electrical responses to the control fuel delivery, the spark timing, and the other emission control systems. The input information interrelates to more than one output; therefore, if the one input fails, the failure can affect more than one system. VCM Learning bility Notice: Since the VCM is located under the hood, its connectors are sealed and cannot be backprobed as in the previous model years. Do not attempt to backprobe as a connector or seal damage could occur. The learning ability of the VCM allows the VCM to make corrections for minor variations in the fuel system in order to improve driveability. When the battery is disconnected for other repairs, the learned connections are lost. The driver may note a change in the performance of the vehicle. The engine must be at normal operating temperature for learning to occur. Drive the vehicle at part throttle with a moderate acceleration and idle condition until the normal performance returns. 2017 General Motors. ll rights reserved.
Document ID: 21209 https://gsi.ext.gm.com/gsi/showdoc.do?laboropcode=&docsyskey=21209&cellid=131739&pub... Page 1 of 6 1995 GMC Truck Sonoma Pickup - 2WD Blazer, Bravada, Jimmy, S10 Pickup, Sonoma VIN S/T Service Manual Engine Engine Controls - 4.3L Repair Instructions Document ID: 21209 VCM Replacement/Programming Removal Procedure Caution: Refer to Battery Disconnect Caution in Cautions and Notices. 1. Disconnect the negative battery cable. 2. Remove the VCM bracket bolts. 3. Lift the inside edge of the VCM bracket until the bottom of the bracket can clear the /C accumulator. 4. Slide the VCM bracket over the /C accumulator. 5. Continue sliding the VCM bracket until the fender side of the bracket is no longer underneath the fender lip. 6. Remove the retainer clips and VCM connectors. 2017 General Motors. ll rights reserved.
Document ID: 21209 https://gsi.ext.gm.com/gsi/showdoc.do?laboropcode=&docsyskey=21209&cellid=131739&pub... Page 2 of 6 7. Remove the VCM from the VCM bracket. 8. Steps 8 10 are only necessary for a VCM replacement: Remove the access cover screws. 9. Remove the VCM access cover.
Document ID: 21209 https://gsi.ext.gm.com/gsi/showdoc.do?laboropcode=&docsyskey=21209&cellid=131739&pub... Page 3 of 6 Important: Since the module will be used in the replacement VCM, place the module in an area where it will not be damaged. 10. Gently pinch the retaining clip and pull upward to remove the Electronic Spark Control module/prom. Installation Procedure Important: Ensure that the VCM being installed is the original VCM, or that the replacement VCM service number is identical to the original VCM service number. Steps 1 4 are only necessary for a new VCM installation: Notice: Refer to Electrostatic Damage to the VCM Notice in Cautions and Notices. 1. lign the notches of the Electronic Spark Control module/prom with the notches in the Electronic Spark Control module/prom socket. Important: Press only on the ends of the Electronic Spark Control module/prom. Gently press on the Electronic Spark Control module/prom until it is firmly seated in the socket. Listen for the click. 2. Install the Electronic Spark Control module/prom in the Electronic Spark Control module/prom socket.
Document ID: 21209 https://gsi.ext.gm.com/gsi/showdoc.do?laboropcode=&docsyskey=21209&cellid=131739&pub... Page 4 of 6 3. Install the access cover on the VCM. Notice: Refer to Fastener Notice in Cautions and Notices. 4. Install the access cover screws. Tighten Tighten the access cover screws to 4.4 5.2 Y (39 46 lb in). 5. Insert the VCM into the VCM bracket. Ensure that the VCM is fully seated, so that the snap retainer is up into its normal position and is retaining the module.
Document ID: 21209 https://gsi.ext.gm.com/gsi/showdoc.do?laboropcode=&docsyskey=21209&cellid=131739&pub... Page 5 of 6 6. Connect the VCM connectors and retainer clips. 7. Insert the VCM bracket at an angle whereby the fender side of the bracket is positioned underneath the fender lip. 8. Push the VCM bracket underneath the lip until the inside edge of the bracket clears the /C accumulator. Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems. 9. Install the VCM bracket bolts. Tighten Tighten the bolts to 9 11 Y (80 97 lb in). 10. Connect the negative battery cable. Important: The MIL, antilock and brake lamps will continue to be enabled until the VCM is programmed. Once the programming is complete, the lamps will turn off and normal operation will occur.
Document ID: 21209 https://gsi.ext.gm.com/gsi/showdoc.do?laboropcode=&docsyskey=21209&cellid=131739&pub... Page 6 of 6 11. If the Electronic Spark Control module/prom was replaced, then program the VCM. VCM Programming 1. Take the following steps in order to set-up for programming the VCM (EEPROM). The battery is fully charged. The ignition is ON. The Data Link Connector (DLC) is secure. 2. Refer to an updated Techline terminal and follow the user's instructions for VCM programming. 3. If the VCM fails to program, do the following functions: Check all the VCM connections. Check the ITCS terminal and equipment for the latest software version. Try again to program the VCM. If the programming fails again, replace the VCM. 4. For a functional check, perform the Powertrain On-Board Diagnostic (OBD) System Check.
Page 1 of 9 1995 GMC Truck Sonoma Pickup - 2WD Blazer, Bravada, Jimmy, S10 Pickup, Sonoma VIN S/T Service Manual Engine Engine Controls - 4.3L Schematic and Routing Diagrams Document ID: 1376837 Connector End Views Connector Part Information 12129025 32 - Way F Micro - Pack 100 Series (Blue) Pin Wire Color Circuit No. Function Component Connector Cavaity DTC(s) ffected Possible Symptoms From a Faulty Cirtuit 1 BLU 830 LF Wheel Speed High B 2 YEL 873 LF Wheel Speed Low 3 BRN/WHT 633 1x Camshaft Position signal B P0340, P0341 4 PNK 539 Ignition Feed 5 YEL/BLK 846 Injector 6 Control P0306 Rough Idle, Loss of Power 6 Not Used 7 TN 1667 HO2S Low Right Bank (Bank 2 Sensor 1) P0152 8 PNK/BLK 632 Camshaft Position Sensor Low P0340, P0341 9 TN 833 RF Wheel Speed Low 10 TN/BLK 422 Tcc Enable T No TCC 2017 General Motors. ll rights reserved.
Page 2 of 9 11 Not Used 12 DK GRN/WHT 428 EVP Purgw Solenoid Control P0440, P0441 Purge Inop 13 WHT 687 3-2 Down Shift Solenoid S Incorrect Gear State 14 Not Used 15 Not Used 16 DK GRN 872 RF Wheel Speed High B 17 Not Used 18 GRY 435 EGR Low P0401, P1406 EGR Inop 19 PPL/WHT 1665 HO2S High Left Bank (Bank 1 Sensor 1) B P0131 20 PPL 1670 HO2S High Pre- Catalyst (Bank 1 Sensor 2) B P0137 21 PPL 1666 HO2S High Right Bank (Bank 2 Sensor 1) B P0151 22 PPL/WHT 1668 HO2S High Post Catalyst (Bank 1 Sensor 3) B P0143 23 Not Used 24 TN/WHT 1671 HO2S Low Pre- Catalyst (Bank 1 Sensor 2) P0138 25 TN/WHT 1653 HO2S Low Left Bank (Bank 1 Sensor 1) P0132 26 TN/WHT 1669 HO2S Low Post Catalyst (Bank 1 Sensor 3) P0144 27 Not Used 28 PPL 574 B No Start
Page 3 of 9 Crankshaft Position Sensor Low P0336, P0338, P0339 29 GRN/BLK 822 VSS Low 30 PPL/WHT 821 VSS High B 31 YEL 573 3x Crankshaft Position Signal P0337, P0338, P0339 No Start 32 Not Used Connector Part Information 12129025 32 - Way F Micro -Pack 100 Series (Red) Pin Wire Color Circuit No. Function Component Connector Cavaity DTC(s) ffected Possible Symptoms From a Faulty Cirtuit 1 Not Used 2 WHT 928 EVP Canister Vent Solenoid 3 BLK 1744 Injector 1 Control P0301 Rough Idle 4 YEL/BLK 1223 2-3 Solenoid B 5 WHT/BLK 967 Brake Enable Relay Control B 6 GRN 1222 1-2 Solenoid a Incorrect Gear State 7 BRN 418 TCC PWM U TCC Inop 8 Not Used
Page 4 of 9 9 DK GRN/WHT 459 /C Relay Enable C1 /C Inop 10 BRN 1456 EGR Pintle Position Signal C 1406 EGR Inop 11 Not Used 12 Not Used 13 GRN/WHT 1749 IC B High B P0507, P0508, P1508, P1509 Incorrect Idle Speed 14 BLU/WHT 1747 IC High D P0507, P0508, P1508, P1509 Incorrect Idle Speed 15 BLK/WHT 1745 Injector 2 Control N P0302 Rough Idle 16 YEL/BLK 1746 Injector 3 Control P0303 Rough Idle 17 Not Used 18 GRN/BLK 1292 4 WL Pump Motor Control D 19 DK BLU 496 KS Signal P0325, P0327 Knock Retard 20 Not Used 21 GRN 432 MP Signal B P0106, P0107, P0108, P1107 Poor Performance 22 TN 472 IT Signal P0112, P0113, P1111, P1112 Poor Performance 23 YEL 410 ECT Signal P0117, P0118, P1114, P1115 Poor Performance 24 DK BLU 417 TP Signal C P0121, P0122, P0123, Poor Performance Harsh Shifts
Page 5 of 9 P1121, P1122 25 DR GRN 890 Fuel Tank Vacuum Sensor B 26 Not Used 27 YEL/BLK 1227 TFT Signal L Early TCC 28 YEL 492 MFSignal P0101, P0102, P0103 Poor Performance 29 GRN/BLK 444 IC B Low P0507, P0508, P1508, P1509 Incorrect Idle Speed 30 BLU/BLK 1748 IC a Low C P0507, P0508, P1508, P1509 Incorrect Idle Speed 31 BLU/BLK 845 Injector 5 Control E P0305 Rough Idle 32 PNK/BLK 844 Injector 4 Control D P0304 Rough Idle Vehicle Control Module (VCM) Connector C3 Connector Part Information 12129025 32 - Way F Micro - Pack 100 Series (Gray) Pin Wire Color Circuit No. Function Component Connector Cavaity DTC(s) ffected Possible Symptoms From a Faulty Cirtuit 1 BLU 1289 RF Isolation Solenoid Control H
Page 6 of 9 2 DK GRN 1288 LF Isolation Solenoid Control C 3 PPL 1722 RR Isolation Solenoid Control K 4 BLK 452 ECT/TP Sensor Ground B High Idle 5 Not Used 6 RED/BLK 1228 PCS High C Poor Shift Quality 7 Not Used 8 Not Used 9 WHT 423 IC Control B P1351, P1361 No Start 10 Not Used 11 RED 1226 Range Signal C P Erratic Manual Downshifts 12 GRY 416 TP Sensor 5V Reference P0121, P0122, P0123, P1121, P1122 Lack of Power Harsh Shifts 13 PPL 379 Clutch Switch Signal P0704 14 Not Used 15 Not Used 16 DK BLU/WHT 1229 PCS Low D Poor Shift Quality 17 TN/WHT 551 Ground Poor Performance 18 BLK/WHT 451 Ground Poor Performance 19 BLK 470 IT/MP/EGR/ TFT/ Fuel Tank Vacuum Sensor Ground Idle Surge Exhaust Odor 20 Not Used
Page 7 of 9 21 ORN 440 Battery Feed 22 DK BLU 1225 Range Signal B R Erratic Manual Downshifts 23 PNK 1224 Range Signal N Erratic Manual Downshifts 24 Not Used 25 DK GRN/WHT 762 /C Request /C Inop 26 Not Used 27 GRY 474 EGR/MP Refernece Poor Performance Rough Idle 28 BLU/BLK 1293 4 WL Pump Motor Feedback E 29 Not Used 30 Not Used 31 Not Used 32 Not Used Connector Part Information 12129225 24 - Way F Micro -Pack 100 Series (Black) Pin Wire Color Circuit No. Function Component Connector Cavaity DTC(s) ffected Possible Symptoms From a Faulty Cirtuit 1 DK GRN/WHT 465 Fuel Pump Relay Control 2 Extended Crank When Cold
Page 8 of 9 2 BRN 834 VSS Output (Electronic Transfer Case) N 3 DK GRN/WHT 817 VSS Output (Cruise Module) 4 DK GRN 389 VSS Output (i/p) Speedometer Inop 5 BRN/WHT 419 MIL Control 24 MIL Inop Or Remains On 6 /GRN 867 BS Lamp Control 5 7 Not Used 8 TN/WHT 33 Brake Lamp Control 17 9 PPL 680 Brake Differential Pressure Switch 10 PPL 420 Brake Signal No TCC 11 PPL 1807 Serial Data 2 No WSerial Data 12 Not Used 13 BRN 441 Ignition Feed 14 PPL 30 Fuel Tank Level Signal P0641,P0643 15 TN/BLK 456 Shift Light Control 26 Shift Light Inop 16 Not Used 17 Not Used 18 PNK 439 Ignition Feed No Start 19 BLK/WHT 1695 4 WD Lamp Control 20 Not Used 21 Not Used 22 Not Used
Page 9 of 9 23 GRY/BLK 1694 wwd Low Indicator 24 BLU/BLK 396 Cruise Signal