Code 37

EGR CONTROL CIRCUIT - DTC 37

When the ignition is switched ON, the ECM looks for an incorrect internal circuit voltage that indicates the state of the EGR solenoid vacuum valve switching circuit. This internal voltage cannot be measured.

The EGR solenoid vacuum valve has a 12-volt power supply from the EMS main relay and is switched ON by the ECM by completing the circuit to ground. When energized, the solenoid valve directs manifold vacuum to the EGR valve. EGR is activated when the engine cootant temperature is above 60°C (14O°F), the transmission is in a driving gear, and the engine is operating within the envelope.

Operating Envelope:

The ECM will flag DTC 37 if the EGR solenoid vacuum valve control circuit is open or short circuit.

Conditions Required For DTC 37 Flagging
Engine - Engine operating.
ECM internal circuit - Indicates that the EGR solenoid vacuum valve control circuit is open or short circuit.
Response time - 100 milliseconds.

Limp Home Default
None

Possible Faults
- Low battery voltage.
- Poor ground connection to ECM.
- Short circuit or open circuit wiring from the ECM to the EGR solenoid vacuum valve.
- Defective EGR solenoid vacuum valve.

Diagnostic Notes
1. The EGR solenoid vacuum valve coil resistance should be 37-44 ohms.
2. With the ignition ON and the engine OFF, there should be approximately 12 volts at pins 1 and 2 on the solenoid vacuum valve.
3. During EGR operation, there should approximately 2 volts at pin 2 on the solenoid vacuum valve.

Circuit Diagram

Circuit Diagram:

Flow Chart - DTC 37

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Flow Chart - DTC 37: