Diagnostic Aids

WARNING: This page is about a different car, the 2004 Pontiac Grand Prix. However, it is still accessible from the selected car via links, so may be relevant.

The following may cause an intermittent:
- A damaged terminal
- A backed out terminal
- A poor terminal tension
- A chafed wire
- A broken wire inside the insulation
When diagnosing an intermittent short or an open, manipulate the wire harness while watching the test equipment for changes.

DTC B1420

Step	Action	Values	Yes	No
Schematic Reference: Body Control System Schematics Connector End View Reference: Body Control System Connector End Views
1	Did you perform the Diagnostic System Check for the system exhibiting the symptom?	-	Go to Step 2	Go to Control Module References
2	Install a scan tool. Turn ON the ignition, with the engine OFF. With a scan tool, observe the battery voltage input parameter in the BCM input data list. Is the battery voltage input parameter in the specified range?	9.0-16.0 V	Go to Step 3	Go to Step 4
3	Is DTC B1420 set as a current DTC?	-	Go to Step 7	Go to Diagnostic Aids
4	Disconnect the body control module (BCM) harness connectors. Measure the voltage between the battery positive voltage circuit at the BCM harness connector and a good ground. Refer to Circuit Testing in Wiring Systems. Is the measured value in the specified range?	9.0-16.0 V	Go to Step 6	Go to Step 5
5	Test the battery positive voltage circuit for a short to ground or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 9	Go to Battery Inspection/Test in Engine Electrical
6	Test the all of ground circuits of the BCM for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 9	Go to Step 7
7	Inspect for poor connections at the module harness connectors. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 9	Go to Step 8
8	IMPORTANT: Perform the module programming or setup procedure if required. Replace the BCM. Refer to Body Control Module Replacement .Did you complete the replacement?	-	Go to Step 9	-
9	Operate the system in order to verify the repair. Did you find and correct the condition?	-	System OK	Go to Step 2