On the way back from the track my check engine light came on and the trans starting surging/bucking. I was able to stop that by shifting to 3rd gear and driving home slow the rest of the way.
Once home, I performed the diagnostic found here [https://www.ls2.com/boggs/a4/DTC%20P1810%203.8.htm] and determined the wiring from the trans to the pcm was good.
So I replaced the TFP Manual Valve Position switch.

I cleared the code and it came back, as did the and the bucking/surging in 4th, so I dropped the trans pan again and pulled out the harness (interestingly its a 2003-2005 4l60e), using my multi-meter, everything checks out, though the connector had some fluid in it and was a little dirty.

The car is a 2001 Camaro 5.7 that had a m4 originally, now has a 4l60e, PO did the swap.

I don't know what to do at this point:

• is the new switch bad?
• is the harness bad in some weird intermittent way?
• is there an internal problem in the transmission?

Anyone else had this issue, where the new TFP switch didn't solve the problem?

 

P1810 is a Pressure Switch Manifold (PSM) code. The last vehicle I worked on for that code, Changing the PSM fixed it. The symptom it had was after driving for 30-40 minutes it would loose 4th gear and Lock up (TCC). Here is a copy of the ATSG codebook for P1810, it may help.
Check the PSM commands and make sure they match what they are supposed to be in each range.

 

I replaced the internal harness, TFP switch(aka PSM) and EPC. Verified that there's voltage at A, B and C right at the TFP switch.
Let the car warm up to top off trans fluid, shut it off, started again, fired up hptuners and could see it thought Park was D2 - and it threw the p1810 code again.

Could the transmission pump be bad? I have zero reason to think this issue is electrical at this point.
EDIT: its electrical, because without the engine running, I should see hi low hi, Im seeing hi hi hi
I'm confused because I tested each circuit by grounding it and was able to get low low low, so the connection should be okay, even saw 12v at the tfp like I said above.

 

Have you inspected the wires from the trans plug up to the PCM. There could be some bad wires between the plug and PCM. Also, you could have received a defective new Manifold Pressure Switch. Did the old and new switches read the same with HP Tuners?

 

I slid under the car again today, not wanting to drop the pan again, I hooked up the old TFP switch and internal harness to the PCM, when I grounded the TFP the PCM read hi low hi, like it should.
So, I would assume there no ground for the TFP - however, when I put the car in reverse or D1 it reads low high high, so IT IS getting a ground.

I could have a defective new TFP manifold switch, but I had this same issue with the old one, and that so far is testing fine. I'm obv doing something wrong.
My next steps are going to be

• drop pan again (I'm getting sick of doing this)
• check that B is going to ground on the TFP switch (normal operation)
  • if it is getting grounded them I'm gonna lose my mind
• play around while i have the scan tool hooked up

 

Dropped pan, removed tfp manual switch
its bad

smacks head
glad I found the problem


don’t order parts from Amazon

 

Glad you got it figured out. You can replace just those seals. You don't have to buy a new switch.