Test Description

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers on the diagnostic table.

2: Listen for an audible click when the auxiliary water pump relay operates. Command both the ON and OFF states. Repeat the commands as necessary.
3: Tests for voltage at the coil side of the auxiliary water pump relay. The AUX HTR PUMP fuse supplies power to the coil side of the auxiliary water pump relay.
4: Verifies that the HCM is providing ground to the auxiliary water pump relay.
5: Tests if ground is constantly being applied to the auxiliary water pump relay.

DTC B3844

Step	Action	Yes	No
Schematic Reference: Engine Cooling Schematics Connector End View Reference: Cooling System Connector End Views
1	Did you perform the Engine Cooling Diagnostic System Check?	Go to Step 2	Go to Diagnostic System Check - Engine Cooling
2	Install a scan tool. Turn ON the ignition, with the engine OFF. With a scan tool, command the Auxiliary Coolant Pump Relay ON and OFF. Does the auxiliary water pump relay turn ON and OFF with each command?	Go to Diagnostic Aids	Go to Step 3
3	Turn OFF the ignition. Disconnect the auxiliary water pump relay. Turn ON the ignition, with the engine OFF. Probe the battery positive voltage circuit of the auxiliary water pump relay with a test lamp that is connected to a good ground. Does the test lamp illuminate?	Go to Step 4	Go to Step 10
4	Connect a test lamp between the control circuit of the auxiliary water pump relay and the battery positive voltage circuit of the auxiliary water pump relay. With a scan tool, command the Auxiliary Coolant Pump Relay ON and OFF. Does the test lamp turn ON and OFF with each command?	Go to Step 8	Go to Step 5
5	Does the test lamp remain illuminated with each command?	Go to Step 7	Go to Step 6
6	Test the control circuit of the auxiliary water pump relay for a short to voltage and an open. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 13	Go to Step 9
7	Test the control circuit of the auxiliary water pump relay for a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 13	Go to Step 9
8	Inspect for poor connections at the auxiliary water pump relay. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 13	Go to Step 11
9	Inspect for poor connections at the harness connector of the HCM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 13	Go to Step 12
10	Repair the battery positive voltage circuit of the auxiliary water pump relay. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair?	Go to Step 13	-
11	Replace the auxiliary water pump relay. Refer to Relay Replacement (Within an Electrical Center) or Relay Replacement (Attached to Wire Harness) in Wiring Systems. Did you complete the replacement?	Go to Step 13	-
12	IMPORTANT: Perform the set up procedure for the HCM. Replace the HCM. Refer to Hybrid Control Module (HCM) Replacement (5.3L Engine w/RPO HP2) in Engine Electrical.Did you complete the replacement?	Go to Step 13	-
13	Use the scan tool in order to clear the DTCs. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text. Does the DTC reset?	Go to Step 2	System OK