Originally Posted by
pizzaguy
Let's go thru this slowly.
So it latches with a clicking sound - but then pops back up, so it did not really latch, did it? And keep in mind, there is no final beep until the cycle completes - the beep happens as soon as the electric trunk lock switches to the "unlocked" position . But this wont happen if the PTCM senses that ANY sensor has not reported proper position. If a sensor indicates proper position and then IMPROPER position before the lock is commanded to unlock, you will also get no beep.
So the lid pops back up, we now know that the tonneau lid didn't really latch.
So, going the other way, the lid does it again (from this description). I can tell you this: At tech days, I have seen the bow latch mechanism fail to actually grab and lock the bow, twice in the last three or four years. BOTH times, lubrication of the bow latch mechanism fixed the problem. I think THAT is what we should try here, with your tonneau lid latch.
The Tonneau cover latch has caused issues, I've never worked on a car with such trouble, but my first reaction would be to lubricate the mechanism. BOTH symptoms that you are seeing implicate the tonneau lid latch mechanism. The fluid pressure and flow are provided by the pump, the control of such flow is done by the PTCM thru the valves in the pump assembly. Certainly a leaky cylinder (and as our cars age, that is more and more common) would cause issues.
But Im still thinking "lubricate the damn thing and see what you get". Like I said, the bow latch has caused issues. I worked on a top last fall - the CLP/SSM had water damage. Once we changed it and the last two feet of the wiring harness feeding it, the top started working, but the bow latch was not working well. The car's owner has a shop full of lubes and oils and greases. He tried some silicon lubricant (he's a retired mechanical engineer) and we worked the top up and down maybe five times. Bow Latch operation improved to the point that, the last two times, it latched just fine.
So, try lubrication and work the top up and down several times. Be rather generous with the lubricant, too.
If that does it, cool. If not, we can consider other ideas.