P166A
DTC P166A
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC P166A
- Exhaust Control Valve Control Circuit
Diagnostic Fault Information
Circuit/System Description
The K27 fuel pump control module receives accelerator pedal position transmission gear and RPM information via serial data from the K20 engine control module. The K27 fuel pump control module uses this information to determine a target position for the tailpipe exhaust valves. To achieve the target position, the K27 fuel pump control module commands the KR146 exhaust flow control valve relay ON or OFF. When commanded ON, the KR146 exhaust flow control valve relay opens the Q15 exhaust flow control valve solenoid, which exposes the left and right tailpipe exhaust valves to vacuum. When exposed to vacuum, the tailpipe exhaust valves will close. When commanded OFF, the KR146 exhaust flow control valve relay closes the Q15 exhaust flow control valve solenoid, which isolates the left and right tailpipe exhaust valves from vacuum. In the absence of vacuum, the tailpipe exhaust valves will open.
Conditions for Running the DTC
* Ignition ON.
* Ignition voltage is greater than 9 V and less than 16 V.
Conditions for Setting the DTC
The K27 fuel pump control module detects a short to voltage on exhaust valve solenoid supply voltage circuit.
Action Taken When the DTC Sets
* DTC P166A is a Type C DTC.
* The Q15 exhaust flow control valve defaults to open.
Conditions for Clearing the DTC
* The condition for setting the DTC is no longer present.
* The history DTC is cleared when a current DTC is not detected in 40 consecutive drive cycles.
Reference Information
Schematic Reference
Exhaust System Schematics Electrical Diagrams
Connector End View Reference
Component Connector End Views Fuel Pump and Level Sensor Assembly - Primary
Description and Operation
Exhaust Tail Pipe Flow Control System Description and Operation Exhaust Tail Pipe Flow Control System Description and Operation
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Verification
1. Ignition ON.
2. Verify the exhaust noise changes modes from quiet to active rumble when commanding the Q15 exhaust flow control valve Open or Closed with a scan tool. The exhaust noise will be in quiet mode when the valve is closed. The exhaust noise will be in active rumble mode when the valve is open.
• If the exhaust noise does not change
Refer to Circuit/System Testing.
• If the exhaust noise changes
3. All OK.
Circuit/System Testing
1. Ignition OFF, disconnect the KR146 exhaust flow control valve relay, ignition ON.
2. Verify a test lamp illuminates between the B+ circuit terminal 30 and ground.
• If the test lamp does not illuminate and the circuit fuse is good
1. Ignition OFF.
2. Test for less than 2 ohms in the B+ circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse.
• If the test lamp does not illuminate and the circuit fuse is open
1. Ignition OFF.
2. Test for infinite resistance between the B+ circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance,
3. Test for greater than 10 ohms between the control circuit terminal 87 and ground.
• If less than 10 ohms, repair the short to ground in the circuit. If the circuit tests good, replace the Q15 exhaust flow control valve.
• If greater than 10 ohms, replace the KR146 exhaust flow control valve relay.
• If the test lamp illuminates
3. Verify a test lamp illuminates between the ignition circuit terminal 85 and ground.
• If the test lamp does not illuminate and the circuit fuse is good
1. Ignition OFF.
2. Test for less than 2 ohms in the ignition circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse.
• If the test lamp does not illuminate and the circuit fuse is open
1. Ignition OFF.
2. Test for infinite resistance between the ignition circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, test or replace the KR146 exhaust flow control valve relay.
• If the test lamp illuminates
4. Connect a test lamp between the ignition circuit terminal 85 and the control circuit terminal 86.
5. Verify the test lamp turns ON and OFF when commanding the Q15 exhaust flow control valve OPEN and CLOSED with a scan tool.
• If the test lamp is always OFF
1. Ignition OFF, disconnect the harness connector at the K27 fuel pump control module, ignition ON.
2. Test for less than 1 V between the control circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V
3. Ignition OFF.
4. Test for less than 2 ohms in the control circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K27 fuel pump control module.
• If the test lamp is always ON
1. Ignition OFF, disconnect the harness connector at the K27 fuel pump control module.
2. Test for infinite resistance between the control circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the K27 fuel pump control module.
• If the test lamp turns ON and OFF
6. Verify a test lamp does not illuminate between the control circuit terminal 87 and ground.
• If the test lamp illuminates
Repair the short to voltage on the circuit.
• If the test lamp does not illuminate
7. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the Q15 exhaust flow control valve. It may take up to 2 minutes for all vehicle systems to power down.
8. Test for less than 10 ohms between the Q15 exhaust flow control valve ground circuit terminal 1 and ground.
• If 10 ohms or greater
1. Ignition OFF.
2. Test for less than 2 ohms in the ground circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If less than 10 ohms
9. Connect the harness connector at the Q15 exhaust flow control valve.
10. Ignition ON, connect a 10 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87.
11. Verify the Q15 exhaust flow control valve is activated.
• If the Q15 exhaust flow control valve does not activate
1. Ignition OFF.
2. Test for less than 2 ohms in the control circuit terminal 87 end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, test or replace the Q15 exhaust flow control valve.
• If the Q15 exhaust flow control valve activates
12. Test or replace the KR146 exhaust flow control valve relay.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Exhaust Tail Pipe Flow Control Valve Solenoid Replacement (LSA)
* Control Module References Control Module References for Fuel Pump Flow Control Module replacement, setup, and programming