2010 Cadillac Truck SRX FWD V6-3.0L Page 1485
1. Ignition OFF, disconnect the KR25 secondary air injection pump relay.
2. Test for 70-110 ohm between terminals 85 and 86.
瀚慖f the resistance is not within the specified range, replace the KR25 secondary air injection pump relay.
3. Test for infinite resistance between the following terminals:
* 86 and 87
* 86 and 30
* 85 and 87
* 87 and 30
瀚慖f not the specified value, replace the KR25 secondary air injection pump relay.
4. Install a 20 A fused jumper wire between relay terminal 86 and 12 V. Install a jumper wire between relay terminal 85 and ground. Test for
less than 2 ohm between terminals 87 and 30.
瀚慖f greater than the specified range, replace the KR25 secondary air injection pump relay.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* Relay Replacement (Attached to Wire Harness) (See: Power and Ground Distribution/Power Distribution Relay/Service and Repair/Relay
Replacement (Attached to Wire Harness))Relay Replacement (Within an Electrical Center) (See: Power and Ground Distribution/Power
Distribution Relay/Service and Repair/Relay Replacement (Within an Electrical Center))
* Secondary Air Injection Pump Replacement (See: Powertrain Management/Emission Control Systems/Air Injection/Air Injection
Pump/Service and Repair)
P0418
DTC P0418, P2257, or P2258
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions)provides an overview of each diagnostic category.
DTC Descriptors
DTC P0418
- Secondary Air Injection Pump Control Circuit
DTC P2257
- Secondary Air Injection Pump Relay Control Circuit Low Voltage
DTC P2258
- Secondary Air Injection Pump Relay Control Circuit High Voltage
Diagnostic Fault Information
Circuit/System Description
The secondary air injection system aids in the reduction of hydrocarbon emissions during a cold start. The electric air pump forces fresh air into the
exhaust stream in order to accelerate the catalyst operation. Ignition voltage is supplied directly to the secondary air injection pump relay. The
engine control module (ECM) controls the relay by grounding the control circuit with a solid state device called a driver. The driver is equipped
with a feedback circuit that is pulled-up to a voltage. The ECM can determine if the control circuit is open, shorted to ground, or shorted to a
