Transmission Code 73

[Melsride8084]

Hey guys, I got a transmission code 73. I followed the tech manual (attachment) and i have continuity thru the lines as well as correct ohms. So following the steps I finished with changing the control solenoid. After putting it all together I still have the 73 code. I started it a few times and even disconnected battery for a bit to try and reset the computer and trans light. Still have the same 73 code. Any ideas what else could be giving me this code or ideas to try and reset the code? Thanks in advance!

 

[NDT]

Does pin j or k have a short to ground?

 

[Melsride8084]

Does pin j or k have a short to ground?

No all wiring from TCM to transmission looks good and has continuity. Then all wiring inside trans looks good and has continuity to the solenoid. I’m going to reluctantly take it for a drive today to warm up the trans to see if there’s a change. I don’t like driving with a light on but out of options. Next phase is taking it to a transmission shop to see if they have any intel. I did see on another post a gentleman changed the TCM and all was well after that. I really don’t want to do that, considering the price for a TCM.

 

[Mogman]

If it ohms out correctly from C15 to C16 at the TCM connector (inside the TCM box) and nether is shorted to ground then it is likely a bad TCM

 

[Melsride8084]

If it ohms out correctly from C15 to C16 at the TCM connector (inside the TCM box) and nether is shorted to ground then it is likely a bad TCM

Ok new intel. Started it and warmed it up. Took for a drive down the street and won’t shift out of 1st gear now. Also not sure if related but my tachometer is not working now. Still thinking bad TCM ?

 

[NDT]

Sounds like limp mode now. TCM very unhappy about something. I take it you are working with Supplement 7?

 

[Melsride8084]

Yes I am following the Supplement 7 guide. It’s a 4 speed. Never had issues prior to this spring. Had a 22 code and 73 code. Cleared the 22 and followed all the wiring, looked good. So ended up changing the pressure control solenoid inside trans. Still no change and now tach isn’t working either So guessing the tach isn’t getting any info from the TCM. I opened the TCM to see if anything looked fried but all looks good. Anyway to test the TCM ? Or am I finally at the point to buy a new computer ? Also heard of a kit that bypasses the TCM and makes your Tran’s work as a manual transmission where you have to shift yourself. Anyone hear of this and or have this? All help and info greatly appreciated!!

 

[NDT]

Those manual shift kits are not a great idea. Word is they slam shift hard which might be fine for drag racing but not normal driving. What codes are you getting now that it won't shift out of 2? You have not told us the results of checking for continuity between the pressure control solenoid wiring and ground.

 

[Melsride8084]

I kind of thought that kit would be hard on trans.
Still only getting code 73. Continuity from TCM all the way to solenoid is good. Checked it at every connection point and the grounds are clean and good. Getting continuity and correct ohms. Replaced solenoid. I feel the only part of the equation unchecked/unknown is TCM itself. Anyway to check them before trying to find a new one ? Again never had a trans issue. Let sit over winter and started it this spring with a 22 and 73. Adjusted TPS that 22 went away. Are TCM’s known to just quit ? Are they fragile? I did notice when I bought the vehicle, it looked like someone was playing with that Tcm and harness under seat. There was wiring outside of it protective coating and an aftermarket connector. Kind of like someone had and issue with a wire breaking and reconnected it. But it was fine for 2 years until now. Can TCM’s be tested? If not, know any reputable places to order one ? Haha thanks guys.

 

[NDT]

Before you condemn the TCM, it is possible that somewhere in the harness, one of the two wires going to the solenoid have chafed against a chassis ground point, which is telling the TCM during it's self check "whoa, ohms here are not right, throw code". We are suggesting you check for this with your multimeter.

 

[thompsoncustom]

I'll be curious what you find out as I have never fixed my code 73 issue with my four speed and everything I checked out always seemed to come back fine.