"There is a problem with the Transmission P Lock mechanism" when road is wet

Hi DMajetich, I assume the attached picture is the connector to the parking pawl motor on the transmission? Were you able to confirm that the corrosion or cracking caused the P lock issue you saw? Did you replace or clean up and seal it, and successfully eliminate the problem?

My 2004 starting showing the P lock message recently, 173000 miles. Only seen while driving, comes and goes, and does not seem to have any effect on car operation - starts, runs, parks just fine. Has never prevented starting. My battery (Optima) tests good, even though the voltage is not quite where I'd like, and of course system voltage with car running is about 14V, so battery should not be a factor for this case. Voltage at the blue wires is always same as system 12V, although I have not been able to check during an incident so I hesitate to just jumper and bypass the blue wire as mentioned in several posts.

I believe this has only occurred for me in wet rainy weather, not when dry.

I am waiting for it to happen again so I can check the voltage at the blue wire in the fuse box, and/or the blue wire on the transmission ECU. I may have to spray the harness to try to bring it out, but I don't quite understand how wetting the wiring would reduce the power voltage to the T-ECU. It makes more sense that this connector you are showing is getting wet from road spray and one of the connections is getting marginal or causing a high resistance short to one of the others or ground.

Seems like the same or similar problem can be caused by several different factors, makes it hard to troubleshoot, or the parse the forum threads about it.

Jack

 

@jack23, yes, the picture was of the parking pawl motor.

So, I finally resolved the problem. Replacing the parking pawl motor was not exclusively the solution. When I figured that much out, I followed up by testing for resistance between the transmission control ECU (T4) pins and the shift control actuator (S1)(parking pawl). Two pins did not meet specs: resistance in the Mega Ohms and shorted together.
Ended up disconnecting the inverter to pull the S1 actuator connector up for visual inspection. The connector was cracked and a couple wires' insulation were compromised and showing conductor.
After replacing the S1 actuator connector, the triangle of death went away. And after 3 successful drive cycles the DTCs also went away. And, so far this week I have logged over 150 miles without further issue.

 

800 more miles logged, and at least a couple heavy downpours; all is well, running like it never had the triangle of death. I'm confident the obvious problems I located were the problem.