Harsh Upshifts (esp. in low gears) / P2716 code (shift solenoid 'D') / Recent OEM Pan Replacement... Thoughts? (4 Viewers)

[Matt Hunoval]

ADDENDUM. TRANSMISSION VODOO STRIKES BACK. Update. This happened late last week, but just now have time to post. To recap, the p2716 error code indicated an electrical failure with the SLT solenoid (or D solenoid)-- it regulates how much ATF fluid at what pressures are necessary at varying RPMs and shift points. After getting into the valve body, the OEM solenoid was showing high & out-of-range resistance of 6.1 ohms (5.0 - 5.6 is the 'normal' range). New SLT / D solenoid installed. Harsh upshift in lower gears remains.

Same damn code popped up.

So shlepped over to the shop and, with the owner, and we:

1) Pulled the just-installed new SLT / D solenoid; checked & rechecked and impedance is at 5.5 ohms, with valve opening & closing smooth as butter as it should. Check.

2) Checked the electrical connection at the valve body to new solenoid. Electric current / connectivity at valve body to SLT solenoid kosher. Check.

3) Pulled & removed the PCM to test wire harness / relays going from PCM to valve body. Electric current / connectivity from PCM wiring / relays to valve body to SLT solenoid kosher. Check.

4) Grounds were all attached & open. Check.

4) Re-attached wire harness / relays to PCM and (using certain electrical equipment I don't have in my garage) attached a 'noid light' into the back of the PCM connector and entered a command to actuate the SLT solenoid. FAIL.

5) So dear readers, the issue has been traced further down and-- for reasons unclear for a 200 series at 145k miles, the PCM is the issue: it isn't sending any signal / current to the SLT / D solenoid.

6) Of course & for my VIN#, new OEM PCMs (part # 89661-60R00) is on backorder for who-knows-how-many-months after numerous calls to 6-7 nearby Toyota / Lexus dealerships & online direct vendors of OEM Toyota / Lexus parts.

7) So my only options are:

a) drive as-is, and toggle the ECT to the 2nd gear setting (again, the most 'aggressive' harshness / jerkiness is only on the 1-2 upshift, maybe 90% less on the 2-3 upshift and not detectable in the 3-4 upshift and higher). If a new OEM PCM had a time-certain for the backorder, this would be the route I'd prefer to take.

b) HOWEVER, no one is able to provide a time-certain date or even timeframe for getting a new OEM PCM (4 months, 6 months, 12 months?)... so the alternative is to purchase a refurbished PCM from 2 online retailers I've found and, since I don't have access to tech stream (technology enabling you to use your keys with a new PCM), that will also be a part of next steps.

Q to all: while I'd prefer to buy a new PCM and have (for this specific repair) have a dealership do it, I have no definite timeline for when I'll be able to source a new OEM PCM... and while toggling the ECT to 2nd is a band-aid work-around to skip over the harsh 1-2 upshift, I don't feel warm & fuzzy re: relying on that for 3-12 months, so am leaning toward buying a refurbished PCM.

Thoughts / input / suggestions welcome. I realize that this entire thread itself is pretty in-the-weeds, and now this sub-issue / Q is even more granular still. But I'm not going to just let the rig sit for the next who-knows-how-long, so need to make a decision one way or the other as to whether to either:

a) wait who-knows-how-long for a new OEM PCM to buy and use the ECT 2nd workaround / band-aid; or

b) buy a refurbished unit.

Aaarrrghhhhh! Well, at the end of this, at least I will have learned a lot more about the voodoo that is the transmission!

 

[linuxgod]

Refurbished probably just means “used and maybe tested”. Unlike a refurbished alternator or starter where there are actually parts being replaced. More than likely it’s just pulled from a wrecked truck.

That said if the cost isn’t awful and/or it’s a significant savings I’d roll the dice on the used one, especially if you can send it back if it doesn’t work. These aren’t generally known to fail AFAIK, so you’re either unlucky or there’s a wiring issue somewhere between the transmission and the ECU.

 

[Matt Hunoval]

Refurbished probably just means “used and maybe tested”. Unlike a refurbished alternator or starter where there are actually parts being replaced. More than likely it’s just pulled from a wrecked truck.

That said if the cost isn’t awful and/or it’s a significant savings I’d roll the dice on the used one, especially if you can send it back if it doesn’t work. These aren’t generally known to fail AFAIK, so you’re either unlucky or there’s a wiring issue somewhere between the transmission and the ECU.

Apologies for my tome, as this has been a 2-month-long troubleshooting exercise and so the update was comprehensive & lengthy to outline the step-by-step elimination of source issue. On the 2013 LX 570, the PCM is integrated into, and part of, the ECU (in Toyota / Lexus speak, the 'ECM').

As part of the drilling down into the weeds process on pinpointing the source of the electrical / circuit failure, we pulled the wiring harness, which runs from the valve body/transmission and into the PCM, and detached it from the PCM to test just that: whether the failure was in the wiring harness, grounds, and related relays going from PCM to valve body / transmission (collectively, the 'wiring harness'). We sent current directly thru the wiring harness at its attachment point to the PCM. And everything checked out & the signal was transmitted thru the wiring harness to the transmission / valve body A-OK.

In sum, all potential electrical failure points from the PCM to the valve body / transmission (including re-testing of the new SLT solenoid installed), checked out & were found to be fully operational & thus eliminated from the source of the problem.

The final step was to re-attach the wiring harness to the PCM, plug a noid light into the back of the PCM with a command for the PCM to, in turn, send a command up thru the wiring harness, to the valve body/transmission, to engage the SLT solenoid. No circuit activity was generated to the SLT solenoid in this final test.

Ergo, after a 2-month-long process of elimination, the source of the issue has been determined to be the PCM driver & the repair for which is replacing the PCM module itself & then two additional steps: a) programming the new (or refurbished) PCM to the rig's specific VIN# and then 2) to use your keys, both to start the ignition and to lock/unlock doors, etc., they must separately be 'married' to the rig-with-new-PCM via separate subscription & technology that logs directly into Lexus/Toyota (tech stream).

Hell, I wish it were the wiring harness, but we've gone thru every electrical / circuit fail point in the chain and everything checks out, other than the PCM itself is failing to send the appropriate signal / current to engage the SLT / D solenoid.

Sooooooo.... unless anyone knows how to actually open up the PCM and install / repair the PCM driver (beyond my pay grade), I'm stuck at either:

1) Driving as-is & engaging the ECT to 2nd at every start to wait months (a year) before a new OEM PCM becomes available (they're on backorder), and then have a dealership both i) install the new PCM and ii) 'marry' the keys.

OR

2) Buy a refurbished PCM (immediately available) and find an independent shop with the appropriate equipment equipment and 'tech stream' capabilities to similarly 'marry' the keys.

Fully realizing there is no 'right' answer here, but, rather an informed risk/benefit analysis, I'm leaning toward option 2-- the refurbished route, as the bigger risk / downside (to me) would be driving my rig for the next 6-9-12 months as-is vs. the risk of a refurbished PCM.

Neither option is optimal, so I'm in the position of making the less bad option, unfortunately.

Thus the request for input / thoughts / wisdom / opinions.

 

[linuxgod]

Apologies for my tome, as this has been a 2-month-long troubleshooting exercise and so the update was comprehensive & lengthy to outline the step-by-step elimination of source issue. On the 2013 LX 570, the PCM is integrated into, and part of, the ECU (in Toyota / Lexus speak, the 'ECM').

As part of the drilling down into the weeds process on pinpointing the source of the electrical / circuit failure, we pulled the wiring harness, which runs from the valve body/transmission and into the PCM, and detached it from the PCM to test just that: whether the failure was in the wiring harness, grounds, and related relays going from PCM to valve body / transmission (collectively, the 'wiring harness'). We sent current directly thru the wiring harness at its attachment point to the PCM. And everything checked out & the signal was transmitted thru the wiring harness to the transmission / valve body A-OK.

In sum, all potential electrical failure points from the PCM to the valve body / transmission (including re-testing of the new SLT solenoid installed), checked out & were found to be fully operational & thus eliminated from the source of the problem.

The final step was to re-attach the wiring harness to the PCM, plug a noid light into the back of the PCM with a command for the PCM to, in turn, send a command up thru the wiring harness, to the valve body/transmission, to engage the SLT solenoid. No circuit activity was generated to the SLT solenoid in this final test.

Ergo, after a 2-month-long process of elimination, the source of the issue has been determined to be the PCM driver & the repair for which is replacing the PCM module itself & then two additional steps: a) programming the new (or refurbished) PCM to the rig's specific VIN# and then 2) to use your keys, both to start the ignition and to lock/unlock doors, etc., they must separately be 'married' to the rig-with-new-PCM via separate subscription & technology that logs directly into Lexus/Toyota (tech stream).

Hell, I wish it were the wiring harness, but we've gone thru every electrical / circuit fail point in the chain and everything checks out, other than the PCM itself is failing to send the appropriate signal / current to engage the SLT / D solenoid.

Sooooooo.... unless anyone knows how to actually open up the PCM and install / repair the PCM driver (beyond my pay grade), I'm stuck at either:

1) Driving as-is & engaging the ECT to 2nd at every start to wait months (a year) before a new OEM PCM becomes available (they're on backorder), and then have a dealership both i) install the new PCM and ii) 'marry' the keys.

OR

2) Buy a refurbished PCM (immediately available) and find an independent shop with the appropriate equipment equipment and 'tech stream' capabilities to similarly 'marry' the keys.

Fully realizing there is no 'right' answer here, but, rather an informed risk/benefit analysis, I'm leaning toward option 2-- the refurbished route, as the bigger risk / downside (to me) would be driving my rig for the next 6-9-12 months as-is vs. the risk of a refurbished PCM.

Neither option is optimal, so I'm in the position of making the less bad option, unfortunately.

Thus the request for input / thoughts / wisdom / opinions.

Timeline aside what is the cost of new vs refurbished (parts and labor) and what guarantee/warranty do you have on the used one?

 

[GrouchyTech]

When I replace a transmission and TCU (transmission ECU) I simply have to input the compensation values and perform an initialization and the test drive outlined in the repair manual.

Regarding a reman— when we get a Toyota reman transmission I’m pretty sure the only thing that isn’t new is the case and maybe the main shaft. They’re good transmissions and I wouldn’t hesitate replace my LC trans with one if/when the time comes.

 

[Matt Hunoval]

When I replace a transmission and TCU (transmission ECU) I simply have to input the compensation values and perform an initialization and the test drive outlined in the repair manual.

Regarding a reman— when we get a Toyota reman transmission I’m pretty sure the only thing that isn’t new is the case and maybe the main shaft. They’re good transmissions and I wouldn’t hesitate replace my LC trans with one if/when the time comes.

danke sir! To be precise (and apologies for my tendency to pen novels-- feel free to dunk on me for that bad habit from my day job as a lawyer coming thru-- the length of my post(s) often compromise precision... my bad)... but the issue is solely electrical. The mechanical transmission is 100% good. Something is up with the internal electrics of the PCM such that, when prompted to upshift at X RPM and Y throttle position or whatever the back-end math is from the TCU, the PCM isn't sending any signals to the SLT solenoid... and oddly only on lower-gear upshifts. Damned if I know why, or how that happened-- admittedly a head-scratcher only attributable to the Vodoo Transmission gods-- but we've eliminated all other sources / causes & by using the noid light plugged into the BACK of the PCM to prompt operation of the SLT solenoid with no resulting signal being generated out of the FRONT of the PCM, and thus into the harness connecting to the valve body & ultimately to (ordinarily) prompt the proper operation of the SLT solenoid... well, that seems fairly determinative!

 

[burtlively]

When I replace a transmission and TCU (transmission ECU) I simply have to input the compensation values and perform an initialization and the test drive outlined in the repair manual.

Regarding a reman— when we get a Toyota reman transmission I’m pretty sure the only thing that isn’t new is the case and maybe the main shaft. They’re good transmissions and I wouldn’t hesitate replace my LC trans with one if/when the time comes.

When I had similar issues with the solenoids this is exactly what my transmission guy said. I wasted time and money chasing down the solenoid issue and the valve body. Wish I’d just bolted up the new transmission right out of the gate.