After Boil Coolant Pump Inoperative
After Boil Coolant Pump Inoperative
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.
Circuit/System Description
The auxiliary coolant pump system provides a measure of prevention against fuel vaporization due to excessive engine temperatures. The engine control module (ECM) commands the auxiliary or after boil coolant pump On when the engine coolant temperature exceeds a calibrated value. The ECM applies ground to the coil side of the auxiliary pump relay. This energizes the coil and applies voltage directly to the pump motor through the switch side of the relay.
Reference Information
Schematic Reference
Engine Cooling Schematics (Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Cooling System Description and Operation (Description and Operation)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
1. Verify that DTCs P2600, P2602 and P2603 are not set.
• If any auxiliary coolant pump DTCs are set, repair the DTC first. Refer to DTC P0480, P0481, P0691, P0692, P0693, or P0694 (w/LLT) (P0480) .
2. Ignition ON, command the auxiliary coolant pump relay ON and OFF with a scan tool. Verify that the pump turns ON and OFF when changing between the commanded states.
Circuit/System Testing
1. Ignition OFF, disconnect the FUEL COOL Relay.
2. Ignition ON, verify that a test lamp illuminates between the relay switch ignition circuit and ground.
• If the test lamp does not illuminate, test the relay switch ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the relay switch ignition circuit fuse is open, test the appropriate relay controlled output circuit for a short to ground. If the circuit tests normal, test or replace the relay.
3. Connect a 10A fused jumper between the relay switch ignition circuit and the relay controlled output circuit. Verify the pump is activated
• If the pump activates, test or replace the relay.
• If the pump does not activate, test the relay controlled output circuit for a short to ground or an open/high resistance. If the circuit tests normal, test the pump ground circuit for an open/high resistance. If the circuit tests normal, replace the pump.
Component Testing
1. Ignition OFF, disconnect the auxiliary coolant pump relay.
2. Test for 70-110 ohms of resistance between terminals 85 and 86.
• If the resistance is not within the specified range, replace the relay.
3. Test for infinite resistance between the following terminals:
* 30 and 86
* 30 and 87
* 30 and 85
* 85 and 87
• If not the specified value, replace the relay.
4. Install a 20A fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms of resistance between terminals 30 and 87.
• If greater than the specified value, replace the relay.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Relay Replacement (Attached to Wire Harness) (Relay Replacement (Attached to Wire Harness))Relay Replacement (Within an Electrical Center) (Relay Replacement (Within an Electrical Center))
* Auxiliary Water Pump Inlet Hose Replacement (Service and Repair)
* Auxiliary Water Pump Outlet Hose Replacement (Service and Repair)
* Auxiliary Water Pump Replacement (4.6L (LH2) w/RPOs V03/V92) (Service and Repair)Auxiliary Water Pump Replacement (LLT) (Service and Repair)