Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET1993ASTRO VAN PASSENGER EXTENDED, 4.3 ZREPAIR AND DIAGNOSISENGINE PERFORMANCESYSTEMENGINE CONTROLS - SYSTEM/COMPONENT TESTSCOMPUTERIZED ENGINE CONTROLSCONTROL UNITQUAD-DRIVER CHECK (EXCEPT 3.1L & 4.3L TURBO)
1993 Chevrolet Astro Van Passenger Extended, 4.3 Z
Quad-Driver Check (Except 3.1L & 4.3L Turbo)
1993 Chevrolet Astro Van Passenger Extended, 4.3 ZSECTION Quad-Driver Check (Except 3.1L & 4.3L Turbo)
- Remove ECM/PCM/VCM from vehicle. Using DVOM on 100/200 k/ohm scale, measure resistance between ECM/PCM/VCM case and each ECM/PCM/VCM quad-driver terminal. Touch negative DVOM lead to case and positive lead to ECM/PCM/VCM terminal. See appropriate ECM/PCM/VCM QUAD-DRIVER TERMINAL IDENTIFICATION table.
- Each terminal should have at least 50 k/ohms resistance. If all quad-driver terminals have greater than 50 k/ohms resistance, go to step 4). If any terminal has less than 50 k/ohms resistance, locate driven component(s) for the quad-driver with the lowest resistance. Disconnect component from circuit and check circuit for short to voltage.
- If circuit is not shorted to voltage, replace component before replacing ECM/PCM/VCM to prevent recurring ECM/PCM/VCM failure. See appropriate ECM/PCM/VCM QUAD-DRIVER TERMINAL IDENTIFICATION table.
- Using a fused ammeter capable of measuring at least 2 amps, turn ignition on with engine off. Connect one lead of ohmmeter to chassis ground. Connect remaining lead to each ECM/PCM/VCM harness quad-driver circuit. Measure each circuit for sustained current flow for at least 2 minutes.NOTE: TCC solenoid cannot be easily tested for current draw, since completed circuit depends upon internal transmission oil pressure switches.
- If no circuit has more than .75 amp sustained current flow, replace ECM. If any circuit has more than .75 amp sustained current flow, check for short to voltage in that circuit. If short to voltage is not present, replace related solenoid or relay.
ECM QUAD-DRIVER TERMINAL IDENTIFICATION (2.5L - "S" SERIES)
| QDR No. | ECM Terminal | Component |
|---|---|---|
| 1 | A2 | Shift Light (M/T) |
| 1 | A2 | TCC Solenoid (A/T) |
| 1 | A4 | A/C Relay |
| 1 | A5 | MIL Light |
| 1 | C1 | Not Used |
| 2 | A3 | EGR Solenoid |
| 2 | A7 | Not Used |
| 2 | C2 | Not Used |
| 2 | D12 | Not Used |
ECM QUAD-DRIVER TERMINAL IDENTIFICATION (2.8L - "S" SERIES)
| QDR No. | ECM Terminal | Component | ||
|---|---|---|---|---|
| 1 | A2 | A/C Relay | ||
| 1 | A3 | Not Used | ||
| 1 | C1 | Not Used | ||
| 1 | C2 | EAC Solenoid | ||
| 2 | A4 | (1) EGR Or EVRV Solenoid | ||
| 2 | A5 | MIL Light | ||
| 2 | A7 | TCC Solenoid (A/T) | ||
| 2 | A7 | Shift Light (M/T) | ||
| 2 | B9 | Not Used | ||
|
||||
PCM QUAD-DRIVER TERMINAL IDENTIFICATION (3.8L WITH 4T60-E TRANSAXLE)
| QDR | PCM Terminal | Component | ||
|---|---|---|---|---|
| A | GC4 | Cooling Fan (Low Speed) | ||
| A | GC5 | Purge Solenoid | ||
| A | GC6 | TCC Solenoid | ||
| B | GC15 | TCC (1) PWM Solenoid | ||
| B | GD15 | Shift Solenoid "B" | ||
| B | GD16 | Shift Solenoid "A" | ||
|
||||
ECM QUAD-DRIVER TERMINAL IDENTIFICATION (4.3L CPI)
| QDR No. | ECM Terminal | Component |
|---|---|---|
| 1 | A2 | TCC Solenoid (A/T) |
| 1 | A4 | Not Used |
| 1 | A5 | MIL Light |
| 1 | C1 | Not Used |
| 2 | A3 | EGR Control |
| 2 | A7 | Intake Tuning Valve |
| 2 | C2 | Not Used |
| 2 | D12 | Not Used |
ECM QUAD-DRIVER TERMINAL IDENTIFICATION (4.3L TBI & V8)
| QDR No. | ECM Terminal | Component | ||
|---|---|---|---|---|
| 1 | A2 | Not Used | ||
| 1 | A3 | Not Used | ||
| 1 | C1 | Not Used | ||
| 1 | C2 | Air By-Pass Control | ||
| 2 | A4 | (1) EGR Or EVRV Solenoid | ||
| 2 | A5 | MIL Light | ||
| 2 | A7 | Not Used | ||
| 2 | B4 | Not Used | ||
|
||||
VCM QUAD-DRIVER TERMINAL IDENTIFICATION (4.3L TBI - "S/T" SERIES PICKUP WITH M/T)
| QDR No. | VCM Terminal | Component |
|---|---|---|
| 1 | C7 | EGR Or EVRV Solenoid |
| 1 | F14 | Shift Light |
| 1 | F15 | Brake Enable Control |
| 2 | E4 | MIL |
| 2 | E5 | Brakelight |
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.