4L80E error code 73 - trans light always on

[RF5]

Then it is definitely coming from the TCM, as I said as long as you have a 73 code that light should be on, since you are doing board level repair I would lok at any electrolytic or tantalum capacitors on the board, I would try to follow the circuit board traces going to the pins associated with the PCS and just shotgun any caps along the way.

Yes, you’re right, thanks again for the help.
I would need a circuit board diagram to check the components related to PCS. Do you know if there is available the diagram?

 

[Mogman]

Yes, you’re right, thanks again for the help.
I would need a circuit board diagram to check the components related to PCS. Do you know if there is available the diagram?

Not that I know of, why I said to follow the traces.

 

[RF5]

I did not see, you have the correct reading (ohms) at the associated pins (C15-D16) around 3-5 ohms at the PCS, yes?

Yes, I did.

 

[RF5]

Not that I know of, why I said to follow the traces.

One more question please.: the 97A/97B wires (STE/ICE TEST switch in the right side of doghouse) could interfere in the error code 73? Mine has these wires disconnected and the tip has a broken plastic, similar to the CPK head, see the photo below.

 

[Mogman]

One more question please.: the 97A/97B wires (STE/ICE TEST switch in the right side of doghouse) could interfere in the error code 73? Mine has these wires disconnected and the tip has a broken plastic, similar to the CPK head, see the photo below.

No, those wires go to the RPM sensor on the back of the engine, they are only used for diag and possibly a tachometer if so equipped.

 

[Mogman]

Although I am not sure why they are on the right side of the doghouse.

 

[RF5]

Although I am not sure why they are on the right side of the doghouse.
View attachment 954964

Mystery…

 

[Milcommoguy]

Mystery…

If they are the 97 A / 97 B they are the tachometer pick up connection. Nothing to do with TCM input.

Looking at the picture location & connectors, ME thinks those wires are the Cold Advance Sensor connections. Look to the engine and I thinks you will find the other part where it seperated from. Wire # 569 & 569 uses the two Packard type connections like in your picture . Tachometer uses round two pin.

Tachometer sender > DOOR 1 Cold advance switch > DOOR 2

I pick door number two, CAMO

 

[RF5]

If they are the 97 A / 97 B they are the tachometer pick up connection. Nothing to do with TCM input.

Looking at the picture location & connectors, ME thinks those wires are the Cold Advance Sensor connections. Look to the engine and I thinks you will find the other part where it seperated from. Wire # 569 & 569 uses the two Packard type connections like in your picture . Tachometer uses round two pin.

Tachometer sender > DOOR 1 View attachment 954965 Cold advance switch > DOOR 2 View attachment 954966

I pick door number two, CAMO

You are completely right. Those wires are 569 connected to 569A and 569B. I saw now this sensor is broken at its head, as shown in the photo.
So, the question is: this sensor can cause the TCM error code 73, allowing the trans light to become always on?

 

[Milcommoguy]

You are completely right. Those wires are 569 connected to 569A and 569B. I saw now this sensor is broken at its head, as shown in the photo.
So, the question is: this sensor can cause the TCM error code 73, allowing the trans light to become always on?

NO No no.

I like the easy ones ? CAMO

 

[RF5]

NO No no.

I like the easy ones ? CAMO

Sorry, but what is CAMO?

 

[Coug]

Sorry, but what is CAMO?

His nickname.