Malleus
Far west of Siegen
So you're not supposed to drive a Land Cruiser through water? That's the first I've ever heard of that.
5-speed A750 trans won't shift in to 5th gear. (3 Viewers)
- Thread starter MongooseGA
- Start date
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It was anecdotal from my friend...
My theory is that either some water got right into some rust spot (e.g. around the windshield or somewhere near ECU) that temporarily messed up the electronic control, or driving in heavy rain for many hours (versus treading water for a minute in offroading) and water got accumulated enough amount to mess something up... I was just suggesting some easy and free checks that may help miraculously. This is more common in the Land Rover/Jaguar/Mercedes world that something unrelated can help fix stuff randomly, thanks to their horrible wiring quality 
The no-5th-gear can be a self-protection mode due to various issues, similar to Land Rover's 3-Amigos mode...
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Malleus
Far west of Siegen
I was picking at you
Could be the dumbest question of the day...I know that in my 4 speed the unit wont shift into top gear if the OD button is toggled on the shifter. Is the 5 speed the same?
The toggle button on the 5spd activates the passenger ejector seat. I deactivated mine since I got married..
Back to serious-
Maybe some cleaning on the electrical connectors leading to the trans might do the trick. I mean, if the shop where it's at doesn't find issues, and before spending a kidney on a replacement unit, I think it's worth a try..
Back to serious-
Maybe some cleaning on the electrical connectors leading to the trans might do the trick. I mean, if the shop where it's at doesn't find issues, and before spending a kidney on a replacement unit, I think it's worth a try..
GTV
SILVER Star
There is no overdrive button on a 5 speed you just drop it into 4th.
- Thread starter
- #27
No debris in fluid. I didn't filter it coming out but I got a good bit in my hands to see how it looked. Definitely not new fluid, but it was nothing alarming either. Dark reddish, no shimmer, no foam, no milkiness. If I was just doing a D&F as regular maintenance, I wouldn't have had a second thought about the condition of the fluid. Trans temp was about 105 when I did the bleed over from the bleed hole (aimed for right in the middle of the 95-115 range) , measured on my Scan Gauge. I didn't measure what came out and replace only that amount, I filled until full and bleeding out, replaced bleed screw, got trans to temp, then bled off the excess after expansion.
Cooling system is perfect. Radiator is newer, clean, good fins, fluid is clean and full, etc.
Trans temp while driving is 150ish, with increases for long acceleration or inclines, and quickly turns to lower normal after the increase in demand.
Short shift issues were likely present prior to the D&F but my only drive time in the truck prior to D&F wouldn't have given me the chance to notice- coming home on the highway at 60MPH with the engine turning 3500-ish RPM and babying the throttle. It was only after the fluid service, driving on local roads where it was noticeable. And I made a point to test this to confirm what I thought I'd felt earlier. Same with kick down, I never had a reason to use it while getting home on the highway. So, I would not suggest the D&F caused these other 2 issues, I just wasn't in a circumstance to really experience them until afterward.
I like the ejector seat answer, but yeah, no OD button on the 5 speeds. Just 5th gear lever position.
Heard from the shop today. They weren't able to get any codes from the trans either, but they feel it's likely a solenoid issue. They hardly ever see these Trans in need of rebuild, save for the ones behind the 5.7 Tundras for some reason. Maybe the extra power
I gave the go ahead for them to pull the pan and test the solenoids, and specified that the unit be refilled with WS at the time. I really do suspect that it's solenoid/ sensor related as there are no slips, flares, hard shifts, hanging shifts etc. Truly, it's perfect other than not going in to 5th this week (and the subsequent short shift and no kick down coinciding).
- Thread starter
- #28
OK well, long story short: we're getting a transmission.
Spoke to the tech today. He found 2 faulty solenoids. Cleaned them, they improved. Checked and cleaned the valve body and now the truck shifts worse. He suspects the torque convertor is giving up the ghost, and suggested just going for a full new unit.
I found one locally, incredibly, with 125k on it that I'll pick up tomorrow. Should be back on the road by the end of the week.
Spoke to the tech today. He found 2 faulty solenoids. Cleaned them, they improved. Checked and cleaned the valve body and now the truck shifts worse. He suspects the torque convertor is giving up the ghost, and suggested just going for a full new unit.
I found one locally, incredibly, with 125k on it that I'll pick up tomorrow. Should be back on the road by the end of the week.
2001LC
SILVER Star
TQ may indeed need replacing. But I don't recall anything you reported in this thread, indicated a bad TQ. Did I miss something.
2001LC
SILVER Star
BTW:
These AT are typically bullet proof. So a used should be fine. But:
When buying major parts like engine, AT, etc. Run the VIN#. Get the carfax and Toyota/Lexus service history. Check mileage reports and look for service(s), that may indicate issue with AT. Treat it, like doing a PPO on a used vehicle purchase. Obviously if buying locally, inspect the fluid personally.
The 04-07 where under filled at factory. Look to see if a Dealership, did a fluid exchange. If a good shop on it's toes. They likely topped properly to the new temp in the TSB.
Look for any indication, may have been in a flood.
Look for any AT issues or codes reported dealing with AT.
- Thread starter
- #31
New trans was picked up this morning and delivered to the shop this afternoon. They're planning to start the swap tomorrow. While in there, we're also going to replace the RMS. No reason not to, and I believe mine was weeping a hair.
- Thread starter
- #32
Well... Not great news. Just spoke to the shop to see if I needed to arrange a ride over this afternoon to pick up. Unfortunately, the truck is doing the same thing that it was when it was dropped off. Shifts perfectly from 1-4, won't go in to 5th. The tech is stumped. His instincts are telling him the torque convertor isn't locking up, keeping the trans from going in to 5th. At this point we're both frustrated and thinking there is something else controlling this.
Is it possible there's a control unit somewhere that may be malfunctioning? What's the electronic brain that would tell the trans to shift in to top gear? Is there a way to manually override the automatic shifting process and just see if it will physically go in to 5th gear? Possible the ABS/VSC/TRAC module is bad and playing a part here? Recall that those 3 idiot lights came on when this issue began.
Is it possible there's a control unit somewhere that may be malfunctioning? What's the electronic brain that would tell the trans to shift in to top gear? Is there a way to manually override the automatic shifting process and just see if it will physically go in to 5th gear? Possible the ABS/VSC/TRAC module is bad and playing a part here? Recall that those 3 idiot lights came on when this issue began.
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- Thread starter
- #34
Wondering if this guy may be a factor:
247carspares.com
Lexus LX470 Toyota Land Cruiser 2003-2005 ABS TRC VSC Module # 89540-6
Lexus LX470 Toyota Land Cruiser 2003-2005 ABS TRC VSC Module # 89540-60430 Used OEM
247carspares.com
- Thread starter
- #35
I’m not familiar enough with how the transmission works. Sounds like it’s not getting the speed signal. I’m surprised you’ve not gotten any codes. What code reader are you using, and does it have the specific add on for your truck? I have OBD Fusion, and when I read codes I have to specify which channel it’s scanning.
- Thread starter
- #37
I run a scan gauge II full time and have another hand held unit as well. Both go through the obd2 port.
I’m not familiar with those scanners. Our trucks have multiple diagnostic channels, and you should get, at the very least, historical codes, given you’ve had lights at least a couple of times. For OBD Fusion I need to select the channel or channels I want to scan, and I do need the Toyota / Lexus plug in for the specific vehicle.
Have you seen any codes in techstream?
- Thread starter
- #40
I'm not sure how they compare. The ScanGauge, to my knowledge, should read any codes that come up in real time. But maybe there's another layer of diagnostics that isn't read through the OBD port?
I don't have TechStream. But I have found something here about jumping ports on the diagnostic module (in the engine bay I believe?) to trigger light flashing on the cluster sort of like OBD1 would have done.
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