4l80 pin out question
Thread Starter
9 Second Club
Joined: Jan 2012
Posts: 126
Likes: 3
From: Post Falls, Id
4l80 pin out question So im having an issue with my 4L80e I am tring to trouble shoot an issue with going into gear. my question is about the pins in the plug. I have good continuity with the wires to the pcm from the trans but when i meter the wires with the pcm plugged in I am not getting a reading on pin M / Blue plug pin 41 . which is gray and supposed to be the TFT sensor ground. so is this wire supposed to have a ground signal all the time? or am I having an issue with ground signal coming out of the PCM
TECH Junkie
Joined: Jun 2008
Posts: 3,203
Likes: 1,391
From: Nitro Alley
Can you please give us a more in depth description of what you are experiencing with the transmission?
Are you stating that the transmission acts as if it is in neutral when you are putting the gear-selector in over-drive?
Do you have any movement of the vehicle in any of the gear-selector positions?
Have you inspected the gear-selector/ transmission range linkage/ cable?
Have you inspected/ tested transmission fluid level and line pressure in the different gear-selector positions?
The "Transmission Fluid Temperature Sensor" is simply a variable negative temperature coefficient thermistor... meaning that it is a variable resistor in which the temperature of the transmission fluid will vary the internal resistance of the sensor/ circuit.
The lower the transmission fluid temperature; the higher the circuit resistance.
-Except for 1993 and older transmissions with original wiring... The transmission fluid temperature circuit passes 5v in through the case electrical connector via terminal "M".
-Through the transmission fluid temperature sensor.
-Then out through the case electrical connector via terminal "L".
Where exactly are you placing the Ohm meter/ multi-meter probes to measure the circuit resistance???
Also... primarily, the purpose of this sensor is to set a PCM diagnostic trouble code when the transmission fluid temperature is higher than the window of safe/ proper temperatures.
Then with the PCM having that data... the torque-converter lock-up clutch can be applied when needed.
Should the transmission fluid temperature be higher than the window of safe/ proper temperatures... The PCM will not have the TCC PWM solenoid lock-up the torque converter clutch.
Are you stating that the transmission acts as if it is in neutral when you are putting the gear-selector in over-drive?
Do you have any movement of the vehicle in any of the gear-selector positions?
Have you inspected the gear-selector/ transmission range linkage/ cable?
Have you inspected/ tested transmission fluid level and line pressure in the different gear-selector positions?
The "Transmission Fluid Temperature Sensor" is simply a variable negative temperature coefficient thermistor... meaning that it is a variable resistor in which the temperature of the transmission fluid will vary the internal resistance of the sensor/ circuit.
The lower the transmission fluid temperature; the higher the circuit resistance.
-Except for 1993 and older transmissions with original wiring... The transmission fluid temperature circuit passes 5v in through the case electrical connector via terminal "M".
-Through the transmission fluid temperature sensor.
-Then out through the case electrical connector via terminal "L".
Where exactly are you placing the Ohm meter/ multi-meter probes to measure the circuit resistance???
Also... primarily, the purpose of this sensor is to set a PCM diagnostic trouble code when the transmission fluid temperature is higher than the window of safe/ proper temperatures.
Then with the PCM having that data... the torque-converter lock-up clutch can be applied when needed.
Should the transmission fluid temperature be higher than the window of safe/ proper temperatures... The PCM will not have the TCC PWM solenoid lock-up the torque converter clutch.
Thread Starter
9 Second Club
Joined: Jan 2012
Posts: 126
Likes: 3
From: Post Falls, Id
My trans is a 2003 4L80e that I have had built up about 7 months ago to handle the HP.
So this is what it is doing, I am using my HPtuners scanner to see what is going on.
So when I shift into gear the gear selector is showing the gear position re: PRN4321 but it doesnt show the solenoids activating, they stay in the off position, also my shift mode PID is staying in the normal D2 position . i have noticed that when i does go into gear the shift mode shows normal shift , when that happens the shift solenoids activate am i get movement. something else I have discovered was that when it shows normal shift my fluid level i dead on the full mark, but when the shift mode is showing normal D2 and the solenoids arnt activating, the fuild level on the dip stick shows 2 quarts over full. what is odd is I can start the engine and put it in gear for about 20 seconds and it moves but then it stops and and it starts doing the issue I am describing above.
I dont know if it will work for you but I will attach my hp log below . It showes what is going on like i said it works when i first start up in this log at 36 sec it all stops working.
Any input would be helpful. just a little more info I have replaced the valve body as well as all my electronics in the trans and the harness, I am thinking it can only be a couple of things left to be the problem,
1 my 411 pcm has gone bad, but only the trans is having an issue
2 the pump is bad in the trans
3 the converter is bad
So this is what it is doing, I am using my HPtuners scanner to see what is going on.
So when I shift into gear the gear selector is showing the gear position re: PRN4321 but it doesnt show the solenoids activating, they stay in the off position, also my shift mode PID is staying in the normal D2 position . i have noticed that when i does go into gear the shift mode shows normal shift , when that happens the shift solenoids activate am i get movement. something else I have discovered was that when it shows normal shift my fluid level i dead on the full mark, but when the shift mode is showing normal D2 and the solenoids arnt activating, the fuild level on the dip stick shows 2 quarts over full. what is odd is I can start the engine and put it in gear for about 20 seconds and it moves but then it stops and and it starts doing the issue I am describing above.
I dont know if it will work for you but I will attach my hp log below . It showes what is going on like i said it works when i first start up in this log at 36 sec it all stops working.
Any input would be helpful. just a little more info I have replaced the valve body as well as all my electronics in the trans and the harness, I am thinking it can only be a couple of things left to be the problem,
1 my 411 pcm has gone bad, but only the trans is having an issue
2 the pump is bad in the trans
3 the converter is bad
TECH Junkie
Joined: Jun 2008
Posts: 3,203
Likes: 1,391
From: Nitro Alley
You should be checking for transmission fluid line pressure at this point.
Even if the transmission had no electrical power connected to the case connector... The transmission would still engage and the vehicle would go forwards.
For example: With the transmission gear selector in over-drive, the manual valve passes line pressure to the forward clutch pack and applies it without any solenoids or anything needing electricity in the hydraulic circuit for the forward clutch.
Even if the transmission had no electrical power connected to the case connector... The transmission would still engage and the vehicle would go forwards.
For example: With the transmission gear selector in over-drive, the manual valve passes line pressure to the forward clutch pack and applies it without any solenoids or anything needing electricity in the hydraulic circuit for the forward clutch.
