Code 26, Quad-Driver Circuit 3.8L W Body: Notes

Fig 1: Code 26 Quad-Driver Circuit Diagram (3.8L W Body)

Courtesy of GENERAL MOTORS CORP.

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