gmJake Posted March 23, 2013 Report Share Posted March 23, 2013 Control Modules (Electrical): Engine (ECM) / Powertrain (PCM), Body (BCM), Automatic Transmission (TCM), and/or other control modules (some new vehicles have more than ten) use input from sensors such as those below to control shift timing and shift feel. When the responsible control module stops working, the transmission may stop shifting, shift harsh or soft, or catastrophically fail. Mass Airflow Sensor (Emission), Throttle Position Sensor (Fuel/Air), and Manifold Absolute Pressure Sensor (Fuel/Air): The Mass Airflow Sensor (MAF) measures the mass flow-rate of air entering the engine. The Throttle Position Sensor (TPS) measures the position of the throttle (gas pedal). The Manifold Pressure Sensor (MAP) measures pressure in the intake manifold. Data from all three sensors can be used to determine engine load. A failed MAF, TPS or MAP can cause late-harsh shifts, early-soft shifts, or the transmission may stop shifting completely. Air Temperature Sensor (Emission): The temperature of the air entering the engine intake is used to adjust the fuel/air mixture and transmission fluid pressure. A failed intake Air Temperature Sensor may cause the transmission to shift harder than normal. Air Conditioner Relay (Electrical-Switch & Relay): The Air Conditioner Relay/Sensor indicates when the AC is on or off. This is used to adjust engine speed (RPM). A failed AC Relay may cause engine lugging or other driveability problems that may seem transmission related. Quote Link to comment Share on other sites More sharing options...
gmJake Posted March 23, 2013 Author Report Share Posted March 23, 2013 Temperature Sender / Sensor (Cooling System and Transmission-Automatic): The Coolant Temperature Sensor and/or Transmission Oil Temperature Sensor prevents the converter clutch from putting the transmission into overdrive when the engine and transmission are too cold. On some cars, other gears may also be inhibited. These sensors are likely to become even more important as more gears are added to new cars with higher fuel economy requirements. Without correct temperature data there may be late shifts, starting off in the wrong gear, and/or no overdrive gear. Quote Link to comment Share on other sites More sharing options...
gmJake Posted March 23, 2013 Author Report Share Posted March 23, 2013 Turbine Speed Sensor (Electrical): This Speed Sensor mounted on the transmission measures input shaft speed and its data indicates if the transmission is slipping. Shift timing and shift feel problems typically occur if the Turbine Shaft Speed Sensor fails. Vehicle Speed Sensor or Differential Speed Sensor (Electrical): The speed sensor mounted on the transmission or differential measures vehicle speed. Without input from this sensor, the transmission may stop shifting or shift late and harsh. The converter clutch may be inhibited and the transmission will not go into overdrive. Quote Link to comment Share on other sites More sharing options...
gmJake Posted March 23, 2013 Author Report Share Posted March 23, 2013 Transmission Range Sensor / Neutral Safety Switch (Electrical-Switch & Relay): This sensor indicates the position of the gear shifter. It determines which gears are enabled or disabled. When this sensor fails, the transmission may start out in the wrong gear, fail to up shift, or seem to fall out of gear. Overdrive Button (Transmission-Automatic): This dash, console, or shifter-mounted switch on some vehicles lets the driver disable overdrive. If the switch fails then the transmission will not go into overdrive or the driver will be unable to disable overdrive. Brake Light Switch (Electrical Switch & Relay): The Brake Light Switch may also generate brake pedal position signals that are used to release the converter clutch when the vehicle is braking. When the Brake Switch fails, the converter clutch may not activate or deactivate properly. The vehicle may shudder while coming to a stop because the transmission is still in a too high of a gear. Quote Link to comment Share on other sites More sharing options...
chpspecial Posted March 24, 2013 Report Share Posted March 24, 2013 Would you rather have a vacuum modulated, kick down cable actuated trans. Me, I'd rather have an electronic trans. Sent from my ADR6400L using Tapatalk 2 Quote Link to comment Share on other sites More sharing options...
Tyson1972 Posted March 24, 2013 Report Share Posted March 24, 2013 Thanks for this thread, I think my speed sensor is going out. I have had trouble with the tranny shifting hard and not shifting out of 3rd gear at WOT. Quote Link to comment Share on other sites More sharing options...
gmJake Posted March 24, 2013 Author Report Share Posted March 24, 2013 Would you rather have a vacuum modulated, kick down cable actuated trans. Me, I'd rather have an electronic trans. Sent from my ADR6400L using Tapatalk 2 Kinda the same thing before ecms. My first car was 70 Nova SS.It had a Holley with vacuum secondaries. Worked like shit. I finally put a Holley with mechanical secondaries on it. What a difference! Quote Link to comment Share on other sites More sharing options...
ccgoodwrench Posted April 1, 2013 Report Share Posted April 1, 2013 I would like to add. I thought I was having a issue with my Converter It turn out to be a P0300 code prohibiting the converter to lock, We'll I think that is the prolbem. Every time I refash the ECM, or clear the codes, The Converter will lock. Quote Link to comment Share on other sites More sharing options...
gmJake Posted April 3, 2013 Author Report Share Posted April 3, 2013 It keeps throwing a P0300 code? Quote Link to comment Share on other sites More sharing options...
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