1998 exp trans problems
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1998 exp trans problems
i have a 1998 expedition 4x4 with the 4.6 liter engine. lately the transmission has really been playing up. when i put it in drive you have to hit the gas for a second or two then it jumps into gear. if yoiu're driving and floor it the rpms jump up and then it'll finally catch and drive. also if i come to a stop it won't down shift to first until you hit the gas like you have to when coming out of park. If I push the o/d button it downshifts to first and shifts just fine when i floor it it down shifts just fine. but even when i have the o/d button pushed when i coming into drive from park or reverse i have to do the same gassing it and it jumps into gear.
transmission bad? torque convertor bad?? the transmission flid was changd like a year ago with mobil 1 synthetic trans fluid. mercon.
transmission bad? torque convertor bad?? the transmission flid was changd like a year ago with mobil 1 synthetic trans fluid. mercon.
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From: Pullman Washington
Check your trans fluid for level and contamination...If the level is good and it does not smell like burnt clutch fibers then it could still be a number of things. All trannies have plenty to go wrong with them internally.
I would also suggest not to be flooring the go-pedal...The BEST thing you could do for yourself AND your vehicle is to find a reputable shop and get some answers.
Brad
I would also suggest not to be flooring the go-pedal...The BEST thing you could do for yourself AND your vehicle is to find a reputable shop and get some answers.
Brad
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I was told by a shop it's a art called the auxillary valve body that gets hung up. says they only need to drop the pan and that's it. anyone know a part number or something. whatever it is he says it's common on my exp. it's making the truck not down shift properly and you have to gas it a bit to get it in gear. anyone know what part he was speaking of and how easy it is to install one.
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From: Pullman Washington
Originally Posted by holiday187
well put it on a scanner at work and there's like 3 codes. also the parts that are sending codes are inside the transmission..........so it will be a rebuilt transmssion.
Brad
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From: Pullman Washington
Originally Posted by holiday187
one was from a somputer that I was told is inside the transmission is this right??
The Powertrain Control Module (PCM) and its input/output network control the following transmission operations:
- Shift timing
- Line pressure (shift feel)
- Torque converter clutch operation. The transmission control is separate from the engine control strategy in the powertrain control module, although some of the input signals are shared. When determining the best operating strategy for transmission operation, the powertrain control module uses input information from certain engine-related and driver-demand related sensors and switches.
The following provides a brief description of each of the sensors and actuators used by the PCM for transmission operation.
Mass Air Flow (MAF) Sensor
The Mass Air Flow (MAF) sensor measures the mass of air flowing into the engine. The MAF sensor output signal is used by the powertrain control module to calculate injector pulse width. For transmission strategies the MAF sensor is used to regulate Electronic Pressure Control (EPC) , shift and torque converter clutch scheduling.
Throttle Position (TP) Sensor
The Throttle Position (TP) sensor is a potentiometer mounted on the throttle body. The TP sensor detects the position of the throttle plate and sends this information to the powertrain control module. The TP sensor is used for shift scheduling, electronic pressure control and Torque Converter Clutch (TCC) control.
Intake Air Temperature (IAT) Sensor
The IAT sensor is installed in the air cleaner outlet tube. The IAT sensor is also used in determining Electronic Pressure Control (EPC) pressures.
Powertrain Control Module (PCM)
The operation of the transmission is controlled by the powertrain control module. Many input sensors provide information to the powertrain control module. The powertrain control module then controls actuators which determine transmission operation.
Transmission Control Switch (TCS) and Transmission Control Indicator Lamp (TCIL)
The Transmission Control Switch (TCS) is a momentary contact switch. When the switch is pressed, a signal is sent to the powertrain control module to allow automatic shifts from first through fourth gears or first through third gears only. The powertrain control module energizes the Transmission Control Indicator Lamp (TCIL) when the switch is off. The TCIL indicates overdrive cancel mode activated (lamp on) and Electronic Pressure Control (EPC) circuit shorted (lamp flashing) or monitored sensor failure.
Anti-Lock Brake Speed Sensor
The Programmable Speedometer/Odometer Module (PSOM) receives input from the rear brake anti-lock sensor. After processing the signal, the PSOM relays it to the Powertrain Control Module (PCM) and the speed control module.
Turbine Shaft Speed (TSS) Sensor
The Turbine Shaft Speed (TSS) sensors a magnetic pickup that sends the Powertrain Control Module (PCM) information on the rotation speed of the coast clutch cylinder assembly The Turbine Shaft Speed (TSS) sensor is mounted externally on the top of the transmission case. The Powertrain Control Module (PCM) uses Turbine Shaft Speed (TSS) sensor signals to help determine Electronic Pressure Control (EPC) pressure, shift scheduling the Torque Converter Clutch (TCC) operation.
<Output Shaft Speed (OSS) Sensor
The Output Shaft Speed (OSS) sensor is a magnetic pickup that provides transmission output shaft rotation speed information to the powertrain control module. The Output Shaft Speed (OSS) sensor is mounted externally on the top of the transmission extension housing. The YCM uses the Output Shaft Speed (OSS) sensor signal to help determine Electronic Pressure Control (EPC) pressure, shift scheduling and Torque Converter Clutch (TCC) operation./P> Transmission Solenoid Body Assembly
The powertrain control module controls the transmission operation through three on/off shift solenoids, one Pulse Width Modulated (PWM) shift solenoid, and one variable force shift solenoid. These solenoids and transmission fluid temperature sensor are housed in the transmission solenoid body assembly. All are part of the transmission solenoid body and are not replaced individually.
Transmission Fluid Temperature (TFT) Sensor
The Transmission Fluid Temperature (TFT) sensor is located on the solenoid body assembly in the transmission sump. It is a temperature-sensitive device called a thermistor. The resistance value of the transmission liquid temperature sensor will vary with temperatures change.
The powertrain control module monitors voltage across the transmission fluid temperature sensor to determine the temperature of the transmission fluid.
The powertrain control module uses this signal to determine whether a cold start shift schedule is necessary. The cold start shift schedule lowers shift speeds to allow for better cold engine operation. The powertrain control module also uses the transmission fluid temperature sensor input to adjust electronic pressure control pressure for temperature effects and to inhibit torque converter clutch operation during the warm-up period.
Coast Clutch Solenoid (CCS) The coast clutch solenoid provides coast clutch control by shifting the coast clutch shift valve. The solenoid is activated by pressing the transmission control switch or by selecting the 1 or 2 range with the transmission range selector lever. In MANUAL 1 and 2, the coast clutch is controlled by the solenoid and also hydraulically as a fail-safe to ensure engine braking. In reverse, the coast clutch is controlled hydraulically and the solenoid is not on.
Torque Converter Clutch (TCC) Solenoid The Torque Converter Clutch (TCC) solenoid provides torque converter clutch control by shifting the converter clutch control valve to apply or release the torque converter clutch.
Electronic Pressure Control (EPC) Solenoid
CAUTION: The Electronic Pressure Control (EPC) solenoid pressure output from the variable force solenoid is NOT adjustable. Any modification to the electronic pressure control solenoid may void the transmission warranty.
The electronic pressure control solenoid is a variable force solenoid. The variable-force type solenoid is an electro hydraulic actuator combining a solenoid and a regulating valve. It supplies electronic pressure control that regulates transmission line pressure and line modulator pressure. This is done by producing resisting forces to the main regulator and the line modulator circuits. These two pressures control clutch application pressures.
Shift Solenoids SSA and SSB
Shift solenoids SSA and SSB provide gear selection of first through fourth gears by controlling the pressure to the three shift valves.
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From: Pullman Washington
CONTINUED!!!! Because there is a BS maximum charector amount??? May want to rethink that a bit...
Digital Transmission Range (TR) Sensor
The digital transmission range sensor is located on the outside of the transmission at the manual lever. The sensor completes the start circuit in Park and Neutral, the back-up lamp circuit in Reverse and a neutral sense circuit for GEM control of 4 x 4 low engagement. The sensor also opens/closes a set of four switches that are monitored by the Powertrain Control Module (PCM) to determine the position of the manual lever (P, R, N, (D), 2, 1).
4x4 Low (4x4L) Switch
The 4x4 low (4x4L) range switch is located on the transfer case cover. It provides an indication of when the 4x4 transfer case gear system is in the low range. The powertrain control module then modifies shift schedule for 4x4L operation.
Brake Pedal Position (BPP) Switch
The Brake Pedal Position Switch (BPP) tells the powertrain control module when the brakes are applied. The torque converter clutch disengages when the brakes are applied. The BPP switch closes when the brakes are applied and opens when they are released.
Electronic Ignition (EI) System
The electronic ignition consists of a crankshaft position sensor, two four tower ignition coils and the powertrain control module. The ignition control module operates by sending crankshaft position information from the crankshaft position sensor to the ignition control module. The ignition control module generates a Profile Ignition Pickup (PIP) signal (engine rpm) and sends it to the PCM. The PIP is one of the inputs that the PCM uses to determine transmission strategy, Wide-Open Throttle (WOT) shift control, torque converter clutch control and EPC pressure.
Distributor Ignition (DI) System
The profile ignition pickup sensor sends a signal to the powertrain control module indicating the engine rpm and the crankshaft position.
Air Conditioning (A/C) Clutch
An electromagnetic clutch is energized when the clutch cycling pressure switch closes. The switch is located on the suction accumulator/drier. The closing of the switch completes the circuit to the clutch and draws it into engagement with the compressor drive shaft. When the A/C clutch is engaged, Electronic Pressure Control (EPC) is adjusted by the PCM to compensate for additional load on the engine.
Manifold Absolute Pressure (MAP) Sensor
The Manifold Absolute Pressure (MAP) sensor senses atmospheric pressure to produce an electrical signal. The frequency of this signal varies with intake manifold pressure. The powertrain control module monitors this signal to determine altitude. The powertrain control module then adjusts the 4R100 shift schedule and EPC pressure for altitude. On diesel engines, the manifold absolute pressure sensor measures boost pressure. The powertrain control module monitors this signal and adjust EPC pressure.
Digital Transmission Range (TR) Sensor
The digital transmission range sensor is located on the outside of the transmission at the manual lever. The sensor completes the start circuit in Park and Neutral, the back-up lamp circuit in Reverse and a neutral sense circuit for GEM control of 4 x 4 low engagement. The sensor also opens/closes a set of four switches that are monitored by the Powertrain Control Module (PCM) to determine the position of the manual lever (P, R, N, (D), 2, 1).
4x4 Low (4x4L) Switch
The 4x4 low (4x4L) range switch is located on the transfer case cover. It provides an indication of when the 4x4 transfer case gear system is in the low range. The powertrain control module then modifies shift schedule for 4x4L operation.
Brake Pedal Position (BPP) Switch
The Brake Pedal Position Switch (BPP) tells the powertrain control module when the brakes are applied. The torque converter clutch disengages when the brakes are applied. The BPP switch closes when the brakes are applied and opens when they are released.
Electronic Ignition (EI) System
The electronic ignition consists of a crankshaft position sensor, two four tower ignition coils and the powertrain control module. The ignition control module operates by sending crankshaft position information from the crankshaft position sensor to the ignition control module. The ignition control module generates a Profile Ignition Pickup (PIP) signal (engine rpm) and sends it to the PCM. The PIP is one of the inputs that the PCM uses to determine transmission strategy, Wide-Open Throttle (WOT) shift control, torque converter clutch control and EPC pressure.
Distributor Ignition (DI) System
The profile ignition pickup sensor sends a signal to the powertrain control module indicating the engine rpm and the crankshaft position.
Air Conditioning (A/C) Clutch
An electromagnetic clutch is energized when the clutch cycling pressure switch closes. The switch is located on the suction accumulator/drier. The closing of the switch completes the circuit to the clutch and draws it into engagement with the compressor drive shaft. When the A/C clutch is engaged, Electronic Pressure Control (EPC) is adjusted by the PCM to compensate for additional load on the engine.
Manifold Absolute Pressure (MAP) Sensor
The Manifold Absolute Pressure (MAP) sensor senses atmospheric pressure to produce an electrical signal. The frequency of this signal varies with intake manifold pressure. The powertrain control module monitors this signal to determine altitude. The powertrain control module then adjusts the 4R100 shift schedule and EPC pressure for altitude. On diesel engines, the manifold absolute pressure sensor measures boost pressure. The powertrain control module monitors this signal and adjust EPC pressure.
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From: Pullman Washington
SO....If you can come up with the actual codes with some kind of exactness there may be a easy way out.
I have swapped out sensors on the vlv. body before with posative results. Pretty easy stuff in regards to sensors.
Brad
I have swapped out sensors on the vlv. body before with posative results. Pretty easy stuff in regards to sensors.
Brad
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i will tell you this once i push the over drive button and i'm out of over drive th truck shifts fine falls back to first at stop lights and everything. but even out of over drive it still has problems withcoming out of park, neutral or reverse. you have to giv it gas then suiddenly it will catch
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it used to quickly go in reverse now it stutters when in reverse. used to give it gas and it would hop into gear. doesn't do that anymore the transmssion is shot. :\ new one coming tomorrow putting it i this weekend.
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