Engine Controls - MIL ON, DTC P0171/P0174, P0172/0175/P1605
T-SB-0058-13April 26, 2013
Flex Fuel Extended Crank due to Alcohol Density Calculation
Service Category
Engine/Hybrid System
Section
Engine Control
Market
USA
Applicability
Introduction
Some 2012 - 2013 model year Sequoia and Tundra vehicles with the 3UR-FBE engine may exhibit a MIL "ON" condition with Diagnostic Trouble Codes (DTCs) P0171/P0174 (System too Lean Bank 1/Bank 2), P0172/P0175 (System too Rich Bank 1/Bank 2), P1604 (Startability Malfunction), and/or P1605 (Rough Idling) after attempting to start the engine. Alcohol Density Estimate values may be high even though the vehicle was fueled with regular fuel (E0/E10). The Engine Control Module/ECM (SAE term: Powertrain Control Module/PCM) logic has been modified to reduce the possibility of this condition occurring. Use the following repair procedure to reprogram the ECM (PCM).
Warranty Information
Parts Information
Calibration Information
Required Tools & Equipment
Repair Procedure
1. Confirm the difficult-to-start condition.
2. Using Techstream confirm one or more of the following DTCs is present:
^ P1604: Startability Malfunction
^ P1605: Rough Idling
^ P0171: System Too Lean (Bank 1)
^ P0172: System Too Rich (Bank 1)
^ P0174: System Too Lean (Bank 2)
^ P0175: System Too Rich (Bank 2)
3. If any of the DTCs listed above is present confirm the Alcohol Density Estimate and fuel trim values.
Is the Alcohol Density Estimate value 15% or greater and are the fuel trim values negative?
^ YES - Reprogram the ECM (PCM). Go to step 4.
^ NO - This bulletin does NOT apply. Continue diagnosis using the applicable Repair Manual.
4. Check for the Authorized Modifications Label affixed to the vehicle in the location shown in Figure 1. Confirm if the ECM (PCM) calibration has been updated. If the calibration ID listed is NOT the latest ECM (PCM) calibration - go to step 5.
5. Flash reprogram the ECM (PCM).
NOTE
^ The GR8 Battery Diagnostic Station MUST be used in Power Supply Mode to maintain battery voltage at 13.5 volts while flash reprogramming the vehicle.
^ For details on how to use the GR8 Battery Diagnostic Station, refer to the located on the Technical Information System (TIS), Diagnostics - Tools & Equipment - Battery Diagnostics.
Follow the procedures outlined in Service Bulletin No. T-58-0012-13, "Techstream ECU Flash Reprogramming Procedure", and flash the ECM (PCM) with the NEW calibration file update.
6. Install the Authorized Modifications Label.
A. Using a permanent marker enter the following information on the label:
^ ECM part number [Refer to the Parts Information section for the CURRENT PART NUMBER]
^ Calibration ID(s) [Refer to the Calibration Identification Chart for the NEW CALIBRATION ID]
^ Dealer Code
^ Repair Date
^ Change Authority [This SB number]
B. Affix the Authorized Modifications Label to the vehicle at the location shown in Figure 1. The Authorized Modifications Label is available through the MDC P/N 00451-00001-LBL.
7. Test drive the vehicle to confirm proper vehicle operation.