There is a lot of ground to cover this month, so let’s jump in right away with a series of bullet points for a variety of transmissions. Chances are good that some issue I address this month will appear in your bays in the coming year, if it hasn’t already.
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• Using PIDs, Transucers to Diagnose Today's Modern Transmissions
• Many 2014 and earlier GM vehicles might exhibit a slight rocking motion forward or backward while in Park at start up after cold soak. A clunking noise might be heard as well. GM notes that this is a slight movement that is more often seen visually, rather than felt, when viewed from the outside and using the auto-start feature, if equipped. This slight movement is due to the residual transmission fluid in the clutch packs that creates a partial apply on start up. The parking pawl and/or transmission fluid exhausting completely from the clutch packs stops this movement. This condition is normal and no repairs should be attempted. This can be verified by comparing with another identically built vehicle under the same cold conditions.
• GM vehicles using the 4L60-E series transmission may exhibit a 2-3 upshift or 3-2 downshift clunking noise. This is a synchronous shift transition between the application and release of the 2-4 band and the 3-4 clutch assembly. GM stipulates that the timing of this shift can cause a momentary torque reversal of the output shaft that results in a clunk noise. This same torque reversal also can occur on a 3-2 downshift when the 3-4 clutch is released and the 2-4 band applied. This condition might be more pronounced on 4-wheel drive vehicles because of the additional tolerances in the transfer case. This is a normal condition; no repairs should be attempted.
• A variety of GM vehicles (as early as 2006 to as late as 2015) might have owners commenting on a hesitation problem when they accelerate the vehicle from a rolling stop.
GM describes the event as starting when a driver coasts at low speeds of less than 15 mph with a closed throttle and then aggressively applies the throttle. Examples of this maneuver include a rolling stop or a lane change maneuver. In this type of maneuver, even though the accelerator is applied aggressively, the throttle blade is opened slowly for up to 0.7 second to help minimize drive-line lash and clunking.
Also in a vehicle equipped with a 6 speed automatic transmission when making a hard, complete stop with a closed throttle immediately followed by an aggressive throttle opening, the transmission down-shifts might not be completed by the time the throttle is opened. As a result, approximately 0.5 second of zero torque might be commanded to allow the shift to first gear to occur.
Both of the above conditions are a result of torque management, and both of these conditions should be considered normal. No repairs should be attempted.
• Customers that own vehicles with the 6L and 6T series transmissions might comment on an illuminated Malfunctioning Indicator Light (MIL). Technicians might find Transmission Control Module (TCM) related codes P0601, P0603, P0604, P062F or P1621 stored in the TCM as an active code or as history codes.
GM states that some of these DTCs also can be set in the Engine Control Module (ECM) or Fuel Pump Control Module (FPCM). Make sure that you know which module has set the DTC before attempting to diagnose and repair this condition. If the DTC is set in a module other than the TCM, those codes will require the appropriate diagnostics. In other words, if these codes are stored in the ECM or the FPCM, the codes are related to the module that is storing them.
If these codes are store in the TCM only, diagnostics for these DTC’s instructs the technician to reprogram the TCM and then recheck to see if the DTC’s has cleared.
The Tech 2 can be used for most programming but certain 2010 thru 2015 models will require the use of Global Diagnostic System 2 (GLDS2) to accomplish the task.
• 2012 Buick LaCrosse and Regal equipped with the 6T40 transmission exhibits a coast downshift bump or jerking sensation from 40 to 30 mph. GM says that this condition is a normal operating characteristic of their vehicle. It will not impact the designed performance or reliability of the vehicle.
• Vehicles equipped with the 6T30/40/45 transmission might develop a TCM communication code U0101. The TCM is mounted on the internal valve and solenoid body assembly referred to as the Transmission Electro Hydraulic Control Module (TEHCM). This condition usually indicates a problem with the internal TEHCM assembly specifically the TCM itself. According to GM, investigations made with several vehicles setting the U0101 code has shown that this condition is caused frequently by issues in areas other than the TEHCM assembly. Due to the elements of weather, temperature extremes and vibration, it is suggested to first inspect the TEHCM connector pins for damage or poor fitting terminals with the external harness connector.
Another area to look at is the underhood fuse block for damaged terminals or poor fitting terminals as well. Also look for mispositioned fuses in fuse block. There have also been issues related to the integrity of the TCM ground circuits G106 and G107.
• Ford and GM might experience noise that sounds like an engine or transmission knock or a hard rattling sound (6T70/6F50). The noise can be heard in Neutral and in gear, but not in Park. Some have been mislead to inspecting the crankshaft to determine the source of the noise. A loose fitting park gear on the spline of the pinion drive gear shaft causes the noise. This loose fitment on the spline is because of the clearance between differential pinion bearing and the park gear. To resolve the concern, install special shims between the bearing and Park gear. Superior Transmission Parts provides a kit to service three repairs, part number ST1005.
• Ford Fiesta (2011-2014) and Ford Focus (2012-2014) might display a Transmission Overheating Stop Safely message in the Base Message Center. Codes related to the Transmission Range Sensor, TCM Power Input and Communication Error Codes between the PCM and the RFA Module (Remote Function Actuator/Keyless Vehicle Module) will accompany the condition. Ford states that these codes might cause the overheat message to be displayed without the transmission overheating. It is suggested by Ford to diagnose the codes set prior to diagnosing the overheat message.
Codes that might be stored are TRS Related Codes: P0706, P0707, P0708, P2801, P2802, P2805. TCM Power Related Codes: P0702 and P0882. Communication Codes: U0100 and U0294
• Some 2008-2010 F-Super Duty 250/350 vehicles with single rear wheels and F-350 dual rear wheels may exhibit an excessive drive-away shudder or vibration under moderate to heavy acceleration from a stop, especially when heavily loaded. This might be due to driveline angle. The shudder or vibration might be more evident while towing a trailer or if vehicle is overloaded. Refer to Ford’s TSB 09-20-5 for detailed angle measuring procedures followed by correctional shim adjustments to eliminate the vibration.
• A number of 2013 F-Super Duty vehicles using the 6R140 transmissions equipped with a Power Take Off assembly (PTO) might exhibit a rattling or chattering type noise when not in operation but dissipates with increased engine speed. This is normal; no action is required. The engine’s firing pulse is being transmitted through the PTO assembly. The noise will vary between the various driveline and chassis packages as well as the different PTO manufacturers being used.
Various 6R80 transmissions between vehicle build dates May 23, 2012, to June 3, 2013, in Ford F-150 3.5L 4X4s might develop a transmission leak requiring the case to be replaced. Fluid might be seen coming out of the case in the bell housing ribs at the 4 and 6 o’clock positions.
• The 2009 to 2010 Escape or Mariner as well as a 2010 Fusion or Milan might have a complaint of fifth gear only and stored diagnostic trouble codes P072F - Stuck In Fourth Gear, P073A - Stuck In Fifth Gear, P073B - Stuck In Sixth Gear, P07A8 - Transmission Friction Element D Stuck Off, P07A9 - Transmission Friction Element D Stuck On, P07AA - Transmission Friction Element E Stuck Off, P0731 - Gear Ratio Error In First Gear or P0732 - Gear Ratio Error In Second Gear after using the Grade Assist feature on a steep downgrade. The Malfunction Indicator Lamp will be illuminated. This is a Powertrain Control Module Software Malfunction which can be remedied by reprogram the PCM to the latest calibration.
Drive with Grade Assist Operation
Pressing the Transmission Control Switch on the side of the gearshift lever activates Grade Assist and cancels Overdrive. This provides additional engine braking and extends lower gear operation on uphill climbs for hilly terrain or mountainous areas. It also provides additional engine braking through the automatic shift strategy which reacts to vehicle inputs such as acceleration, accelerator pedal, brake pedal and vehicle speed.
In addition, it allows the transmission to select gears that will provide the desired engine braking based on the vehicle inputs mentioned above. This will increase engine rpm during engine braking.
Next, the Grade Assist lamp in the instrument cluster will be illuminated. Grade Assist is designed to aid the driver with optimal gear selection in hilly terrain or mountainous areas, but is not intended for normal operation. It is recommended to return to overdrive operation on flat surfaces for optimum fuel economy and transmission function.
To return to overdrive operation, press the transmission control switch once after which the Grade Assist lamp in the instrument cluster will turn OFF and the transmission will operate in gears one through six. Overdrive operation is automatically returned each time the engine is turned off and restarted.
The 2012-2013 Dodge Ram 4.7L or 5.7L engine vehicles equipped with automatic transmissions might experience a whine, howl and/or humming noise at speeds below 30 mph (48 kph) with engine speeds between 1,200 to 1,500 rpms. The noise emanates from the transmission cooling lines going to the transmission cooler. Dodge provides a foam sleeve kit (part No. 68217310AA) to be installed on each line reducing the noise considerably.
Also, 5.7L Jeep vehicles (09-12 Grand Cherokee (WK), 09-10 Commander (XK) and 11-12 Durango (WD) might develop the an erratic or inconsistent initial 2-3 upshift (3-4 upshift on 2012 MY vehicles) and/or sluggish performance during low speed/rolling stop maneuvers (2012 MY vehicles only). There is a Transmission Enhancement programming fix for this concern part No. 0427506AB, which also includes enhanced torque converter lock-up schedule to reduce transmission operating temperatures for 2009 model year vehicles only.