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 MANUALSCHEVROLET1987HI-CUBE 6.2 J, 475/M40REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 45 (DIAGNOSIS - A/T)DIAGNOSTIC FLOW CHARTS (CARS)CODE 26, QUAD-DRIVER CIRCUIT 3.8L W BODYNOTES
1987 Chevrolet Hi-Cube 6.2 J, 475/M40
Code 26, Quad-Driver Circuit 3.8L W Body: Notes
1987 Chevrolet Hi-Cube 6.2 J, 475/M40SECTION Notes
WARNING: This page does not describe the selected car, but rather 138 other vehicles, including the 1992 Saturn SL2, 1992 Saturn SL1, 1992 Saturn SL, 1992 Saturn SC, and 1992 Pontiac Trans Sport. However, it is still accessible from the selected car via links, so may be relevant.
Each ECM Quad Driver has a fault line which is monitored by the ECM. The ECM compares voltage values of the fault line with acceptable values in ECM memory. If the ECM senses other than accepted values, a Code 26 will set.
NOTE:
Test numbers refer to test numbers on diagnostic chart.
- The ECM does not know which controlled circuit set the Code 26 so this chart will go through each circuit to determine which is at fault. On vehicles equipped with an ECM controlled hot light, this test check hot light driver and hot light circuit.
- QDM SYMPTOMS
- TCC inoperative, Code 39
- Hot light on all the time, off during bulb check
- Cooling fans on low speed all of the time or will not come on at all
- Poor driveability due to 100 percent canister purge
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.