Jumped into the deep end and don't know how to swim in the transmission pool

[tbeson]

Great news, got the engine up and running, no leaks and holding oil pressure and water temps, got brakes, lights, all engine systems seem to be normal.

However, now on to the deep end -- I don't know any thing about the transmission, after getting the electrics all sorted out and getting the engine running, I notice the yellow trans light next to the shifters lit up and stays solid. Is there a code reader to diagnose what could be wrong? Or this something best left to the professionals? My thought is that this is a 4L80E 4 speed transmission, GM standard 1998 6.5 set up, similar to most Chevy Diesel trucks from the late 90's era to describe to the transmission shop.

 

[Action]

Direction to pull codes are in the TM.
basically, you stick the ends of s paperclip into A and E in the unused port on TCM. Disconnect the GPC or TSU, so the plugs dont light. Turn start switch to RUN. Codes will flash on that yellow light.You need to write down the codes or have a helper. There series will start and end with 12. It will flash 1 time, pause, then flash two times. That is “12”. It will give “12” three times, then trouble codes will flash, three times each. Then will flash “12” three more times to show test is finished.
if you get “12” six times in a row, problem could be electrical.
Dont put the paperclip in the wrong pin holes. At least one of them is always hot.

 

[REF]

My M1123 did the same thing, Light came on as soon as the unit was switched on but when the engine started it stayed on. On mine it was the RPM signal from the engine telling the TCU the engine was running. I was lucky in that the plugs had been pulled apart at the sender.
Good Luck.
(edit) This would be the sensor on the left front of the engine by the harmonic balancer I believe wire numbers 349B and 359J. Not to be confused with the sensor in the back of the engine valley .

 

[tbeson]

My M1123 did the same thing, Light came on as soon as the unit was switched on but when the engine started it stayed on. On mine it was the RPM signal from the engine telling the TCU the engine was running. I was lucky in that the plugs had been pulled apart at the sender.
Good Luck.
(edit) This would be the sensor on the left front of the engine by the harmonic balancer I believe wire numbers 349B and 359J. Not to be confused with the sensor in the back of the engine valley .

So to follow up, your sending unit was unplugged and you had no transmission at all, then plugged in the sensor and light went out and transmission worked?
I know nothing about transmissions.

 

[REF]

So to follow up, your sending unit was unplugged and you had no transmission at all, then plugged in the sensor and light went out and transmission worked?
I know nothing about transmissions.

No the trans would go into gear and shift even though the light stayed on / I noticed the torque converter was locked up all the time and I don't believe it would go into overdrive but I didn't drive it much until I was able to sort it out. Will your truck not Move ? not even in limp mode ?

 

[tbeson]

Great news, got the engine up and running, no leaks and holding oil pressure and water temps, got brakes, lights, all engine systems seem to be normal.

However, now on to the deep end -- I don't know any thing about the transmission, after getting the electrics all sorted out and getting the engine running, I notice the yellow trans light next to the shifters lit up and stays solid. Is there a code reader to diagnose what could be wrong? Or this something best left to the professionals? My thought is that this is a 4L80E 4 speed transmission, GM standard 1998 6.5 set up, similar to most Chevy Diesel trucks from the late 90's era to describe to the transmission shop.

No the trans would go into gear and shift even though the light stayed on / I noticed the torque converter was locked up all the time and I don't believe it would go into overdrive but I didn't drive it much until I was able to sort it out. Will your truck not Move ? not even in limp mode ?

No, it is dead in the water, will not move at all, I have called a local transmission shop to look over and give advice. I really don't know where to start. It has clean red fluid., but other than that I'm at a loss.

 

[REF]

No, it is dead in the water, will not move at all, I have called a local transmission shop to look over and give advice. I really don't know where to start. It has clean red fluid., but other than that I'm at a loss.

Sorry I assumed in the original post that the truck would move and needed the the light and or codes sorted out, afraid I can't help
Good Luck

 

[tbeson]

Sorry I assumed in the original post that the truck would move and needed the the light and or codes sorted out, afraid I can't help
Good Luck

Hey this forum has saved me tons of time and money, thanks for your reply.

 

[REF]

Hey this forum has saved me tons of time and money, thanks for your reply.

Not trying to be smart But ; If the truck won't move at all, have you checked to make sure the transfer case is in gear. Look under the truck (safely) see if the drive shafts are moving, bad transfer case/ broken diff or missing- broken half shaft could all cause it not to move. May have multiple problems to sort out .

 

[tbeson]

Not trying to be smart But ; If the truck won't move at all, have you checked to make sure the transfer case is in gear. Look under the truck (safely) see if the drive shafts are moving, bad transfer case/ broken diff or missing- broken half shaft could all cause it not to move. May have multiple problems to sort out .

No all good here., when I picked up the truck the torque converter was disconnected from the flywheel and front diff shaft was off, so I was able to figure the front diff was in good order, checked the transfer case and worked smoothly through 4H L 4H N 4 L no binding or grinding as I spun the shafts with my hands, Put the front drive shaft back on and bolted up the torque converter and nothing when the engine is running, it is if there is no pump pressure to engage the transmission. again I am guessing, I can take one out and put a new one back in but how this thing works??

 

[NDT]

Unbolted torque converter directly from USMC means they got started pulling the trans due to it being shot and then someone figured out it was eligible to go to excess so away it went.

 

[tbeson]

Unbolted torque converter directly from USMC means they got started pulling the trans due to it being shot and then someone figured out it was eligible to go to excess so away it went.

That would explain most of what I have found. I have it over at a local transmission shop to see how shot it is....