Buick Regal: Malfunction Indicator Lamp (MIL) Diagnosis
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 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 Aids
If the condition is intermittent, move the related harnesses and connectors
while monitoring the scan tool
MIL control circuit status parameters. Perform this test with the ignition ON
and the engine OFF, and
with the engine running. The MIL control circuit status parameters change from
OK or Not Run to
Malfunction if there is a condition with a circuit or a connection.
Reference Information
Schematic Reference
- Engine Controls Wiring Schematics (LTG)
- Instrument Cluster Wiring Schematics
Connector End View Reference
Component Connector End View Index
Electrical Information Reference
- Circuit Testing
- Connector Repairs
- Testing for Intermittent Conditions and Poor Connections
- Wiring Repairs
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
NOTE: Any MIL requesting DTCs that may be set should be diagnosed
first.
1. Ignition ON.
2. Verify the parameters listed below do not display Malfunction when commanding
the Malfunction
Indicator Lamp On and Off with a scan tool.
- The MIL Control Circuit Low Voltage Test Status
- The MIL Control Circuit Open Test Status
- The MIL Control Circuit High Voltage Test Status
- If Malfunction is displayed
Refer to Circuit/System Testing.
- Go to next step: If Malfunction is not displayed
3. Engine running.
4. Verify the parameters listed below do not display Malfunction when commanding
the Malfunction
Indicator Lamp On and Off with a scan tool.
- The MIL Control Circuit Low Voltage Test Status
- The MIL Control Circuit Open Test Status
- The MIL Control Circuit High Voltage Test Status
- If Malfunction is displayed
Refer to Circuit/System Testing.
- Go to next step: If Malfunction is not displayed
5. Verify the malfunction indicator lamp turns ON and OFF when commanding the
Malfunction
Indicator Lamp On and Off with a scan tool.
- If the malfunction indicator lamp does not turn ON and OFF
Refer to Circuit/System Testing.
- Go to next step: If the malfunction indicator lamp turns ON and OFF
6. All OK.
Circuit/System Testing
1. Ignition OFF.
2. Disconnect the X1 harness connector at the K20 Engine Control Module.
3. Ignition ON, verify the malfunction indicator lamp does not illuminate.
- If the malfunction indicator lamp illuminates
- Test for infinite resistance between the control circuit terminal X1 71
and ground.
- If less than infinite resistance, repair the short to ground in the
circuit.
- If infinite resistance, replace the P16 Instrument Cluster.
- Go to next step: If the malfunction indicator lamp does not
illuminate
4. Connect a 3 A fused jumper wire between the control circuit terminal X1 71
and ground.
5. Verify the malfunction indicator lamp illuminates.
- If the malfunction indicator lamp illuminates
Replace the K20 Engine Control Module.
- If the malfunction indicator lamp does not illuminate
- Test for less than 1 V between the control circuit terminal X1 71 and
ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- Go to next step: If less than 1 V
- Ignition OFF.
- 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.
- Go to next step: If less than 2 Ω.
6. Ignition OFF, disconnect the X1 harness connector at the instrument
cluster.
7. Ignition ON, verify a test lamp illuminates between the ignition voltage
circuit terminal 8 and
ground.
- If the test lamp does not illuminate and the circuit fuse is open
- Ignition OFF.
- Test for infinite resistance between the ignition voltage circuit and
ground.
- If less than infinite resistance, repair the short to ground on the
circuit.
- If the test lamp does not illuminate and the circuit fuse is good
- Ignition OFF.
- Test for less than 2 Ω in the ignition voltage circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- Go to next step: If the test lamp illuminates
8. Replace the P16 Instrument Cluster.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
- Instrument Cluster Replacement
- Control Module References for 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 prior to using this diagnostic
procedure: Diagnostic
System Check - Vehicle
Review the description of Strategy Based Diagnosis: Strate
SEE MORE:
GM recommends the use of TOP
TIER Detergent Gasoline to keep
the engine cleaner and reduce
engine deposits. See
www.toptiergas.com for a list of TOP
TIER Detergent Gasoline marketers
and applicable countries.
Do not use any fuel labeled E85 or
FlexFuel. Do not use gasoline with
ethanol levels great
HUD System
The windshield is part of the HUD
system. If the windshield needs to
be replaced, be sure to get one that
is designed for HUD or the HUD
image may look out of focus.
Driver Assistance Systems
If the windshield needs to be
replaced and the vehicle is
equipped with a front camera sensor
for