Buick Regal: DTC P16A7, P16AF, or P16B3
Diagnostic Instructions
- Perform the Diagnostic System Check - Vehicle prior to using this
diagnostic procedure.
- Review Strategy Based Diagnosis for an overview of the diagnostic
approach.
- Diagnostic Procedure Instructions provides an overview of each
diagnostic category.
DTC Descriptors
DTC P16A7
Engine Controls Ignition Relay Feedback Circuit 2
DTC P16AF
Engine Controls Ignition Relay Feedback Circuit 2 Low Voltage
DTC P16B3
Engine Controls Ignition Relay Feedback Circuit 2 High Voltage
Diagnostic Fault Information
Engine Controls Ignition Relay
Typical Scan Tool Data
Engine Controls Ignition Relay Control Circuit Low Voltage, Open, and High
Voltage Test Status -
Component Commanded OFF
Engine Controls Ignition Relay Control Circuit Low Voltage, Open, and High
Voltage Test Status -
Component Commanded ON
Circuit/System Description
There are 3 ignition voltage circuits supplied to the engine control module (ECM).
Two are supplied by
the engine controls ignition relay, and the other is supplied by the ignition
main relay. The ECM
monitors and compares the ignition voltage supplied by the 2 relays.
Conditions for Running the DTC
P16A7
- The engine controls ignition relay is commanded ON.
- Ignition voltage is greater than 5.5 V.
- The DTC runs continuously when the above conditions are met.
P16AF
- The engine controls ignition relay is commanded ON.
- Ignition 1 signal voltage is greater than 11 V.
- The DTC runs continuously when the above conditions are met.
P16B3
The DTC runs when the engine controls ignition relay is commanded OFF.
Conditions for Setting the DTC
P16A7
The ECM detects that the voltage level difference is greater than 3 V between
the engine controls
ignition relay feedback circuit 2 and the ignition 1 signal circuit for greater
than 1 s.
P16AF
The ECM detects the engine controls ignition relay feedback circuit 2 is less
than 5 V.
P16B3
The ECM detects the engine controls ignition relay feedback circuit 2 is
greater than 4 V for greater than
5 s.
Action Taken When the DTC Sets
- DTC P16A7 is a Type A DTC.
- DTC P16AF is a Type C DTC.
- DTC P16B3 is a Type B DTC.
Conditions for Clearing the DTC
- DTC P16A7 is a Type A DTC.
- DTC P16AF is a Type C DTC.
- DTC P16B3 is a Type B DTC.
Diagnostic Aids
The engine controls ignition relay may also be labeled the powertrain relay,
the engine control module
relay, or the main relay. The ignition main relay may also be labeled the
run/crank relay, the ignition run
relay, the ignition 1 relay, or the ignition relay.
Reference Information
Schematic Reference
- Engine Controls Wiring Schematics (LTG)
- Power Distribution Wiring Schematics
Connector End View Reference
Component Connector End View Index
Component View Reference
Powertrain Component Views
Electrical Information Reference
- Circuit Testing
- Connector Repairs
- Electrical Center Identification Views
- Testing for Intermittent Conditions and Poor Connections
- Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
NOTE: A short to voltage on other components may cause DTC P16B3
to set. If any other DTC is set, diagnose that DTC first.
If you were sent here from Engine Cranks But Does Not Run,
proceed to Circuit/System Testing.
1. Ignition ON, observe the scan tool DTC information. Verify DTC P16A7,
P16AF, or P16B3 is not
set.
- If any of the DTCs are set
Refer to Circuit/System Testing.
- Go to next step: If none of the DTCs are set
2. Operate the vehicle within the Conditions for Running the DTC. You may
also operate the vehicle
within the conditions that you observed from the Freeze Frame/Failure Records
data.
Refer to Circuit/System Testing.
- Go to next step: If the DTC does not set
3. All OK.
Circuit/System Testing
NOTE: You must perform the Circuit/System Verification before
proceeding with
Circuit/System Testing unless sent here from Engine Cranks But Does
Not Run.
1. Ignition OFF, disconnect the KR75 Engine Controls Ignition Relay.
2. Verify a test lamp illuminates between ground and the B+ terminals listed
below:
- Terminal 85
- Terminal 30
- If the test lamp does not illuminate
Replace the front compartment fuse block.
- Go to next step: If the test lamp illuminates
NOTE:
- Go to next step: High resistance in the circuit/underhood
fuse block for either the KR75 Engine Controls Ignition
Relay or the KR73 Ignition Main Relay can cause DTC
P16A7 to set.
- Go to next step: A short to voltage on any of the circuits
supplied by the engine controls ignition relay can cause
DTC P16B3 to set.
3. Ignition ON.
4. Verify that a test lamp does not illuminate between the ignition voltage
circuit terminal 87 and
ground.
- If the test lamp illuminates
- Ignition OFF, disconnect the X1 harness connector at the K20 Engine
Control Module.
- Ignition ON.
- Test for less than 1 V between ground and connector terminal 73.
- If 1 V or greater, repair the short to voltage in the circuit.
- If less than 1 V, replace the K20 Engine Control Module.
- Go to next step: If the test lamp does not illuminate
5. Ignition OFF, connect a 20 A fused jumper wire between the B+ circuit
terminal 30 and the
ignition voltage circuit terminal 87.
6. Ignition ON.
7. Verify the scan tool Engine Controls Ignition Relay Feedback Signal parameter
displays B+.
- Ignition OFF, disconnect the X1 harness connector at the K20 Engine
Control Module
- Test for less than 2 Ω in the relay switch ignition voltage circuit end
to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- Go to next step: If less than 2 Ω
- Test for infinite resistance between the relay switch ignition voltage
circuit and ground.
- If less than infinite resistance, repair the short to ground on the
circuit.
- If infinite resistance, replace the K20 Engine Control Module.
- Go to next step: If B+ is displayed
8. Ignition OFF, connect a DMM, set to the diode setting, between control
circuit terminal 86 and
ground.
9. Verify the DMM displays OL.
- Disconnect the X1 harness connector at the K20 Engine Control Module.
- Test for infinite resistance between ground and the relay control
circuit.
- If less than infinite resistance, repair the short to ground in the
circuit.
- If infinite resistance, replace the K20 Engine Control Module.
- Go to next step: If OL is displayed
10. Ignition ON.
11. Verify the DMM displays less than 1 V.
- Ignition OFF, disconnect the X1 connector at the K20 Engine Control
Module.
- Ignition ON.
- Test for less than 1 V on the relay control circuit.
- If 1 V or greater, repair the short to voltage on the circuit.
- Go to next step: If less than 1 V
- Test for less than 2 Ω in the control circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- if less than 2 Ω, replace the K20 Engine Control Module.
- Go to next step: If less than 1 V
12. Test or replace the KR75 Engine Controls Ignition Relay.
Component Testing
Relay Test
1. Ignition OFF, disconnect the KR75 Engine Controls Ignition Relay.
2. Test for 70 - 110 Ω between terminals 85 and 86:
- If less than 70 Ω or greater than 110 Ω
Replace the KR75 Engine Controls Ignition Relay.
- Go to next step: If between 70 - 110 Ω
3. Test for infinite resistance between the terminals listed below:
- 30 and 86
- 30 and 87
- 30 and 85
- 85 and 87
- If less than infinite resistance
Replace the KR75 Engine Controls Ignition Relay.
- Go to next step: If infinite resistance
4. Install a 20 A fused jumper wire between relay terminal 85 and 12 V.
Install a jumper wire
between relay terminal 86 and ground.
5. Test for less than 2 Ω between terminals 30 and 87.
Replace the KR75 Engine Controls Ignition Relay.
- Go to next step: If less than 2 Ω
6. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
- Relay Replacement (Attached to Wire Harness) or Relay Replacement
(Within an Electrical
Center)
- Control Module References for engine control module replacement,
programming, and setup.
READ NEXT:
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this
diagnostic procedure.
Review Strategy Based Diagnosis for an overview of the diagnostic
approach.
Diag
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this
diagnostic procedure.
Review Strategy Based Diagnosis for an overview of the diagnostic
approach.
Diag
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic
procedure.
Review Strategy Based Diagnosis for an overview of the diagnostic approach.
Diagnosti
SEE MORE:
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this
diagnostic procedure.
Review Strategy Based Diagnosis for an overview of the diagnostic
approach.
Diagnostic Procedure Instructions provides an overview of each
diagnostic category.
Diagnostic Fault
* PLEASE READ THIS FIRST *
NOTE: Examples used in this article are general in nature and do not
necessarily
relate to a specific engine or system. Illustrations and procedures have
been chosen to guide mechanic through engine overhaul process.
Descriptions of processes of cleaning, inspection, ass