INTRODUCTION
Pin voltage charts are supplied (where available) to reduce diagnostic time. Checking pin voltages at the electronic control unit determines whether the control unit is receiving and transmitting proper voltage signals. Charts may also help determine if control unit harness has shorts or opens.
Note. Unless stated otherwise in testing procedures, all voltage tests should be performed with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance.
Note. This ECM voltage chart can be used with a digital voltmeter to save time in diagnosis. Voltages on vehicle being tested may vary slightly from these due to battery voltage or alternator charging level.
Following conditions must be met before testing
- Engine at operating temperature.
- Engine in closed loop operation.
- Engine idling (ENG. RUN column).
- ALDL "test" terminal not grounded.
- Scan tester not installed.
Note. The following figures are Courtesy of General Motors.
4.3L VIN Z (CAPRICE)
| Circuit | Pin No. (Wire Color) | Ckt. No. | Volts KOEO | Volts KOER |
|---|
| Fuel Pump Relay Drive | A1 (Dk Grn/Wht) | 465 | 0 (6) (2) | B+ (2) |
| Canister Purge Solenoid Control | A3 (Dk Grn/Yel) | 428 | 0 (6) | B+ |
| EGR Solenoid Control | A4 (Gray) | 435 | B+ | B+ |
| "SERVICE ENGINE SOON" Light | A5 (Brn/Wht) | 419 | 0 (6) | B+ |
| Ignition Feed | A6 (Pink/Blk) | 439 | B+ | B+ |
| TCC Control | A7 (Tan/Blk) | 422 | B+ | B+ |
| Serial Data | A8 (Orange) | 461 | 3-5 (3) | 3-5 (3) |
| Diagnostic "Test" Terminal | A9 (Wht/Blk) | 451 | 5 | 5 |
| Vehicle Speed Sensor Signal | A10 (Brown) | 437 | (1) | (1) |
| CTS, TPS and IAT Sensor Ground | A11 (Black) | 452 | 0 (6) | 0 (6) |
| ECM Ground | A12 (Blk/Wht) | 450 | 0 (6) | 0 (6) |
| Battery | B1 (Orange) | 480 | B+ | B+ |
| Fuel Pump Signal | B2 (Gray) | 120 | 0 (6) (4) | B+ (4) |
| Distributor Ground Reference Low | B3 (Blk/Red) | 453 | 0 (6) | 0 (6) |
| Reference | B5 (Ppl/Wht) | 430 | 0 (6) | 1.5 |
| Spark Retard Signal (ESC) | B7 (Black) | 485 | 9.0 | 9.0 |
| A/C Status Sugnal | B8 (Lt Blue) | 67 | (7) | (7) |
| Park/Neutral (P/N) Switch Signal | B10 (Orn/Blk) | 434 | 0 (6) (5) | 0 (6) (5) |
| (1) Terminal pins not listed are not used. (2) Varies from .60 to battery voltage depending on position of drive wheels. (3) 12 volts for first two seconds. (4) Varies. (5) 12 volts when fuel pump is running. (6) Reads battery voltage in gear. (7) "OFF" - 0, "ON" - B+. |
| (1) | Terminal pins not listed are not used. |
| (2) | Varies from .60 to battery voltage depending on position of drive wheels. |
| (3) | 12 volts for first two seconds. |
| (5) | 12 volts when fuel pump is running. |
| (6) | Reads battery voltage in gear. |
CONNECTOR "A-B" TERMINAL PIN VOLTAGE CHART (1)
| Circuit | Pin No. (Wire Color) | Ckt. No. | Volts KOEO | Volts KOER |
|---|
| Air Control Solenoid | C1 (Blk/Pnk) | 429 | B+ | 0 (7) |
| Air Switch Solenoid | C2 (Brown) | 436 | B+ | B+ |
| IAC "B" Low | C3 (Lt Grn/Blk) | 444 | (2) | (2) |
| IAC "B" High | C4 (Lt Grn/Wht) | 443 | (2) | (2) |
| IAC "A" High | C5 (Lt Blu/Wht) | 441 | (2) | (2) |
| IAC "A" Low | C6 (Lt Blu/Blk) | 442 | (2) | (2) |
| 4th Gear Switch Signal | C7 (Lt/Blue) | 446 | B+ | B+ |
| Power Steering Pressure Switch | C8 (Lt Blu/Orn) | 495 | B+ (5) | 0 (7) (5) |
| Crank Signal | C9 (Ppl/Wht) | 806 | 0 (4) | 0 (4) |
| CTS Signal | C10 (Yellow) | 410 | 1.6 (3) | 1.6 (3) |
| MAP Sensor Signal | C11 (Lt Green) | 432 | 4.75 (6) | 1.1 (6) |
| IAT Sensor Signal | C12 (Tan) | 472 | 2.5 (3) | 2.5 (3) |
| TPS Signal | C13 (Dk Blue) | 417 | .5 | .5 |
| +5 Volts Reference | C14 (Gray) | 416 | 5 | 5 |
| Battery | C16 (Orange) | 480 | B+ | B+ |
| ECM Ground | D1 (Tan/Wht) | 551 | 0 (7) | 0 (7) |
| MAP Sensor Ground | D2 (Purple) | 455 | 0 (7) | 0 (7) |
| EST | D4 (White) | 423 | 0 (7) | 1.1 |
| Bypass | D5 (Tan/Blk) | 424 | 0 (7) | 4.5 |
| Oxygen (O2) Sensor Ground | D6 (Tan) | 413 | 0 | 0 |
| Oxygen (O2) Sensor Signal | D7 (Purple) | 412 | .3-.5 (2) | .1-.9 (2) |
| Injector 2 Driver | D14 (Dk Green) | 468 | B+ | B+ |
| Injector 1 Driver | D16 (Dk Blue) | 467 | B+ | B+ |
| (1) Terminal pins not listed are not used. (2) Varies. (3) Varies with temperature. (4) Reads battery voltage in gear. (5) 12 volts when engine is cranking. (6) With power steering load, engine running. (7) Less than .5 volt. |
| (1) | Terminal pins not listed are not used. |
| (3) | Varies with temperature. |
| (4) | Reads battery voltage in gear. |
| (5) | 12 volts when engine is cranking. |
| (6) | With power steering load, engine running. |
CONNECTOR "C-D" TERMINAL PIN VOLTAGE CHART (1)
Black 24 PIN A-B Connector/Pin Voltage, 4.3L VIN Z, (Caprice). Scheme 1
Scheme 1: Black 24 PIN A-B Connector/Pin Voltage, 4.3L VIN Z, (Caprice)
Black 32 PIN C-D Connector/Pin Voltage, 4.3L VIN Z, (Caprice). Scheme 2
Scheme 2: Black 32 PIN C-D Connector/Pin Voltage, 4.3L VIN Z, (Caprice)
5.0L VIN E & 5.7L VIN 7 (ALL MODELS)
| Circuit | Pin No. (Wire Color) | Ckt. No. | Volts KOEO | Volts KOER |
|---|
| Fuel Pump Relay Drive | A1 (Dk Grn/Wht) | 465 | 0 (7) (3) | B+ (3) |
| Evap. Canister Purge Solenoid Ctrl Valve | A3 (Dk Grn/Yel) | 428 | 0 (7) | B+ |
| EGR Solenoid Control | A4 (Gray) | 435 | B+ | B+ |
| MIL "Service Engine Soon" Light | A5 (Brn/Wht) | 419 | 0 (7) | B+ |
| Ignition Feed | A6 (Pnk/Blk) | 439 | B+ | B+ |
| TCC Control | A7 (Tan/Blk) | 422 | B+ | B+ |
| Serial Data | A8 (Orange) | 461 | 3-5 (4) | 3-5 (4) |
| Diagnostic "Test" Terminal | A9 (Wht/Blk) | 451 | 5 | 5 |
| Vehicle Speed Sensor Signal | A10 (Brown) | 437 | (2) | (2) |
| ECT, TP and IAT Sensor Ground | A11 (Black) | 452 | 0 (7) | 0 (7) |
| ECM Ground | A12 (Blk/Wht) | 450 | 0 (7) | 0 (7) |
| Battery | B1 (Orange) | 480 | B+ | B+ |
| Fuel Pump Signal | B2 (Gray) | 120 | 0 (7) (5) | B+ (5) |
| Distributor Ground Reference Low | B3 (Blk/Red) | 453 | 0 (7) | 0 (7) |
| Reference | B5 (Ppl/Wht) | 430 | 0 (8) | 1.5 |
| Knock Sensor System Signal | B7 (Black) | 485 | 9.0 | 9.0 |
| A/C Status Sugnal | B8 (Lt Blue) | 67 | (8) | (8) |
| Park/Neutral (P/N) Position Sw. Signal | B10 (Orn/Blk) | 434 | 0 (7) (6) | 0 (7) (6) |
| (1) Terminal pins not listed are not used. (2) Varies from .60 to battery voltage depending on position of drive wheels. (3) 12 volts for first two seconds. (4) Varies. (5) 12 volts when fuel pump is running. (6) Reads battery voltage in gear. (7) Less than .5 volt. (8) "OFF" - 0, "ON" - B+. |
| (1) | Terminal pins not listed are not used. |
| (2) | Varies from .60 to battery voltage depending on position of drive wheels. |
| (3) | 12 volts for first two seconds. |
| (5) | 12 volts when fuel pump is running. |
| (6) | Reads battery voltage in gear. |
CONNECTOR "A-B" TERMINAL PIN VOLTAGE CHART (1)
| Circuit | Pin No. (Wire Color) | Ckt. No. | Volts KOEO | Volts KOER |
|---|
| Electric Diverter Valve Solenoid | C1 (Blk/Pnk) | 429 | B+ | B+ |
| A/C Relay Control | C2 (Dk Grn/Wht) | 459 | 0 (7) (5) | 0 (7) B+ (5) |
| IAC "B" Low | C3 (Lt Grn/Blk) | 444 | (2) | (2) |
| IAC "B" High | C4 (Lt Grn/Wht) | 443 | (2) | (2) |
| IAC "A" High | C5 (Lt Blu/Wht) | 441 | (2) | (2) |
| IAC "A" Low | C6 (Lt Blu/Blk) | 442 | (2) | (2) |
| 4th Gear Switch Signal | C7 (Lt/Blue) | 446 | B+ | B+ |
| Power Steering Pressure Switch (If Used) | C8 (Lt Blu/Orn) | 495 | B+ (6) | 0 (7) (6) |
| Crank Signal | C9 (Ppl/Wht) | 806 | 0 (7) (4) | 0 (7) (4) |
| ECT Sensor Signal | C10 (Yellow) | 410 | 1.6 (3) | 1.6 (3) |
| MAP Sensor Signal | C11 (Lt Green) | 432 | 4.75 (2) | 1.1 (2) |
| IAT Sensor Signal | C12 (Tan) | 472 | 2.5 (3) | 2.5 (3) |
| TPS Signal | C13 (Dk Blue) | 417 | .7 | .7 |
| +5 Volts Reference | C14 (Gray) | 416 | 5 | 5 |
| Battery | C16 (Orange) | 480 | B+ | B+ |
| ECM Ground | D1 (Tan/Wht) | 551 | 0 (7) | 0 (7) |
| MAP Sensor Ground | D2 (Purple) | 455 | 0 (7) | 0 (7) |
| EST | D4 (White) | 423 | 0 (7) | 1.1 |
| Bypass | D5 (Tan/Blk) | 424 | 0 (7) | 4.5 |
| Oxygen (O2) Sensor Ground | D6 (Tan) | 413 | 0 (7) | 0 (7) |
| Oxygen (O2) Sensor Signal | D7 (Purple) | 412 | .3-.5 | .1-.9 |
| Injector 2 Driver | D14 (Dk Green) | 468 | B+ | B+ |
| Injector 1 Driver | D16 (Dk Blue) | 467 | B+ | B+ |
| (1) Terminal pins not listed are not used. (2) Varies. (3) Varies with temperature. (4) 12 volts when engine is cranking. (5) B+ with engine running and A/C "ON". (6) With power steering load, engine running. (7) Less than .5 volt. |
| (1) | Terminal pins not listed are not used. |
| (3) | Varies with temperature. |
| (4) | 12 volts when engine is cranking. |
| (5) | B+ with engine running and A/C "ON". |
| (6) | With power steering load, engine running. |
CONNECTOR "C-D" TERMINAL PIN VOLTAGE CHART (1)
Black 24 PIN A-B Connector/Pin Voltage - 5.0L VIN E & 5.7L VIN 7 (All Models). Scheme 3
Scheme 3: Black 24 PIN A-B Connector/Pin Voltage - 5.0L VIN E & 5.7L VIN 7 (All Models)
Black 32 PIN C-D Connector/Pin Voltage - 5.0L VIN E & 5.7L VIN 7 (All Models). Scheme 4
Scheme 4: Black 32 PIN C-D Connector/Pin Voltage - 5.0L VIN E & 5.7L VIN 7 (All Models)
