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Tahoe / Yukon Service Manual

DTC P157A or P16D7-P16D9

Engine Controls and Fuel - 3.0L LM2 Diesel | Diagnostic Information and Procedures | Document ID: 5999680 Diagnostic Instructions Perform the Diagnostic System Check prior to using this diagnostic procedure: Diagnostic System Check - Vehicle Review the description of Strategy Based Diagnosis: Strategy Based Diagnosis An overview of each diagnostic category can be found here: Diagnostic Procedure Instructions DTC Descriptor DTC P157A Sensor Supply Voltage Feedback Circuit High DTC P16D7 Sensor Supply Voltage Control Circuit DTC P16D8 Sensor Supply Voltage Control Circuit Low DTC P16D9 Sensor Supply Voltage Control Circuit High Diagnostic Fault Information

Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performanc
B+ — Relay Switch U029D, U029E, U02A1, U02A3, U100B, U18A2, U18E2*, ** U029D, U029E, U02A1, U02A3, U100B, U18A2, U18E2* — —
Control — Component U029D, U029E, U02A1, U02A3, U100B, U18A2, U18E2*, ** U029D, U029E, U02A1, U02A3, U100B, U18A2, U18E2* P157A —
Control — Relay Coil P16D8 P16D7 P16D9 —
Ground — Relay Coil — P16D7 — —
* Additional DTCs may set ** The fuse opens

Circuit/System Description

Circuit Description
© 2023 General B+ — Relay Switch Motors. All rights reserved. Supplied from a fuse

B+ Relay Switch Supplied from a fuse.

Circuit Description
Control — Component The output circuit is switched to 12 V to activate the component.
Control — Relay Coil The output circuit is switched to 12 V to activate the component.
Ground — Relay Coil Chassis Ground
Component Description
K20 Engine Control Module The control module contains a microprocessor used to process input data to control outputs. The control module controls a series of actuators to ensure optimal engine performance. The control module does this by reading values from a variety of sensors, interprets the data and adjusts the engine actuators accordingly.
KR200 Engine Controls Sensor Supply Voltage Relay A relay is a switch that is actuated by a solenoid. KR200 is part of the component: X50A Engine Wiring Harness Junction Block

Conditions for Running the DTC P157A DTC P16D7, P16D8, P16D9 = Not set KR200 Engine Controls Sensor Supply Voltage Relay = Off Frequency the DTC runs = Continuously — After the running conditions are met P16D7, P16D8 Ignition and Start Signal = Greater than 11 V KR200 Engine Controls Sensor Supply Voltage Relay = Off Frequency the DTC runs = Continuously — After the running conditions are met P16D9 Ignition and Start Signal = Greater than 11 V KR200 Engine Controls Sensor Supply Voltage Relay = On Frequency the DTC runs = Continuously — After the running conditions are met Conditions for Setting the DTC P157A Control module K20 detects: Serial Data Activity @ After ignition Off — For greater than 2 s P16D7, P16D8, P16D9 Control circuit terminal 64 X1 @ K20 Engine Control Module = Commanded state does not match the actual state — For greater than 2 s Actions Taken When the DTC Sets DTCs listed in the DTC Descriptor category = Type A DTC — Exceptions listed below DTC P16D7 = Type B DTC Conditions for Clearing the DTC DTCs listed in the DTC Descriptor category = Type A DTC — Exceptions listed below DTC P16D7 = Type B DTC Reference Information Schematic Reference Data Communication Schematics Engine Controls Schematics Connector End View Reference Master Electrical Component List Electrical Information Reference Circuit Testing Connector Repairs 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 Circuit/System Verification

  1. Ignition » On / Vehicle » In Service Mode
  2. Verify DTC P16D7, P16D8, P16D9 is not set. ⇒ If any of the DTCs are set Refer to: Circuit/System Testing — Test 1 ⇓ If none of the DTCs are set
  3. Verify DTC P157A is not set. ⇒ If the DTC is set Refer to: Circuit/System Testing — Test 2 ⇓ If the DTC is not set
  4. Perform the scan tool control function: Sensor Supply Voltage » On Verify the scan tool parameter: Sensor Supply Voltage Control Circuit High Test Status = Not Run or Okay Sensor Supply Voltage Control Circuit Low Test Status = Not Run or Okay Sensor Supply Voltage Control Circuit Open Test Status = Not Run or Okay – Perform the action while monitoring the parameter: Wiggle the harness and connector: K20 Engine Control Module Wiggle the harness and connector: X50A Engine Wiring Harness Junction Block ⇒ If not the specified state Repair as necessary » Wiring / Terminal(s) / Electrical Connector(s) ⇓ If the specified state
  5. 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. Verify the DTC does not set. ⇒ If the DTC sets Repeat the procedure starting at step 1 ⇓ If the DTC is not set
  6. All OK. Circuit/System Testing Test 1
  1. Ignition/Vehicle & All vehicle systems » Off
  2. Disconnect the electrical connector: X1 @ K20 Engine Control Module
  3. Ignition » On / Vehicle » In Service Mode
  4. Momentarily connect a 3 A fused jumper wire between the test points: Control circuit terminal 64 & B+ Verify a click cannot be heard or felt at the component when connecting and disconnecting the jumper wire: X50A Engine Wiring Harness Junction Block ⇒ If a click can be heard or felt Replace the component: K20 Engine Control Module ⇓ If a click cannot be heard or felt
  5. Ignition/Vehicle » Off & Remove » Jumper wire(s)
  6. Remove the component: X50A Engine Wiring Harness Junction Block
  7. Test for less than 10 Ω between the test points: Ground circuit terminal A4 X1 @ Fuse/Junction Block Harness & Ground ⇒ If 10 Ω or greater 7.1. Disconnect the ground connection: { Silverado / Sierra } G104 { Escalade / Suburban / Tahoe / Yukon } G102A 7.2. Test for less than 2 Ω between the test points: Ground circuit terminal A4 X1 @ Fuse/Junction Block Harness & The other end of the circuit @ Ground terminal ⇒ If 2 Ω or greater » Repair the open/high resistance in the circuit. ⇒ If less than 2 Ω » Repair the open/high resistance in the ground connection. ⇓ If less than 10 Ω
  8. Ignition » On / Vehicle » In Service Mode
  9. Test for less than 1 V between the test points: Control circuit terminal 64 @ Control module harness & Ground ⇒ If 1 V or greater Repair the short to voltage on the circuit. ⇓ If less than 1 V
  10. Ignition/Vehicle » Off
  11. Test for infinite resistance between the test points: Control circuit terminal 64 @ Control module harness & Ground ⇒ If less than infinite resistance Repair the short to ground on the circuit. ⇓ If infinite resistance
  12. Test for less than 2 Ω between the test points: Control circuit terminal 64 @ Control module harness & Terminal C5 X3 @ Fuse/Junction Block Harness ⇒ If 2 Ω or greater Repair the open/high resistance in the circuit. ⇓ If less than 2 Ω
  13. Test or replace the component: X50A Engine Wiring Harness Junction Block Test 2
  14. Ignition/Vehicle & All vehicle systems » Off
  15. Remove the component: F60UA Fuse & F80UA Fuse @ X50A Engine Wiring Harness Junction Block
  16. Connect a test lamp between the test points: Input terminal @ F80UA Fuse & Ground
  17. Ignition » On / Vehicle » In Service Mode
  18. Perform the scan tool control function: Sensor Supply Voltage » On and Off Verify the test lamp turns On and Off. ⇒ If the test lamp does not turn On and Off Test or replace the component: X50A Engine Wiring Harness Junction Block ⇓ If the test lamp turns On and Off
  19. Verify a test lamp does not turn On between the test points: Output terminal @ F80UA Fuse & Ground Output terminal @ F60UA Fuse & Ground ⇒ If the test lamp turns On Repair the short to voltage on the circuit. ⇓ If the test lamp does not turn On
  20. Replace the component: K20 Engine Control Module Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification Engine Wiring Harness Junction Block Replacement — KR200 Engine Controls Sensor Supply Voltage Relay For control module replacement, programming, and setup refer to: Control Module References