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Hello and thanks for question. You say it want shift into first, is it starting off in second and not shifting? The first thing I would do is verify a good voltage source at the transmission, because if you lose power by default it operates in second gear. Also dont drop the pan since you have already replaced the solenoid pack we need to access the pcm and check resistance of each of those solenoids at the pcm connector that way were checking the wiring and the connector at the trans.
1. Check the governor pressure sensor voltage Key On Engine Off (KOEO). It should be about 0.5 -0.7 volts.2. Monitor the desired governor pressure. If that goes higher along with vehicle speed, the Output Shaft Speed (OSS) sensor is working OK.3. If the OSS sensor is working OK, replace the governor pressure solenoid.
Tech Tips:The OSS sensor is used by the Powertrain Control Module (PCM) to control the governor pressure. The governor pressure sensor is monitored by the PCM, so the PCM can achieve the desired governor pressure. As the output shaft speed increases, the duty cycle to the governor pressure solenoid will come down. The pressure comes up creating the upshifts.
Okay lets look at this. Have you scanned the module for any codes? Having a code would give us a good starting point.
. Check the resistance of the Output Shaft Speed (OSS) sensor. It should be 500-750 ohms.2. Inspect the wiring harness between the OSS sensor and the Powertrain Control Module (PCM).
Tech Tips:The speedometer gets vehicle speed from the rear axle speed sensor. The OSS sensor is only used to control governor pressure in the transmission
Do you have a scan too? Voltmeter? Have you tried swapping the trans relay with another known good relay? They are a common item to fail espicially if you had a solenoid pack go out its a good idea to replace with new. the 3-4 solenoid if it is open or shorted the pcm will cut the ground to relay causing power loss. the oss if it is open you would not know it other than your shifting problem. And finally the pcm ive had multiple failures of the pcm the quad driver that turns the trans relay on fails. but being that this problem is temperature sensitive lets look at the solenoids and the sensor.
Good morning I will be on here all day will be checking in with you
hi okay let me reveiw the code
Okay you say that you are not getting any voltage from relay until the truck warms up. Then you most likely have a faulty pcm we can check that by removing the relay and check the voltage on pins 85 and 86one of those will be voltage with key on the other will be a ground provided by the pcm. And for the pcm to fail and not provide that ground is pretty common. Easy to check just when its cold remove relay and see if you have voltage with your leads on 85 86
Okay now we know our problem. YOur pcm is not energizing the trans relay.
The most likely cause of this is a faulty pcm. But to be sure you can check all the powers and grounds to the pcm if they are all good we can check for the relay command directly at the pcm if not present. YOu need to replace the pcm